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Effect of different milk-removal strategies at weaning on feed intake and behavior of goat kids
Journal Pre-proof Effect of different milk removal strategies at weaning on feed intake and behavior of goat kids Gosia Zobel, Hannah Freeman, Trevor Watson, Catherine Cameron, Mhairi Sutherland PII:
S1558-7878(19)30063-2
DOI:
https://doi.org/10.1016/j.jveb.2019.10.004
Reference:
JVEB 1279
To appear in:
Journal of Veterinary Behavior
Received Date: 11 March 2019 Revised Date:
4 June 2019
Accepted Date: 1 October 2019
Please cite this article as: Zobel, G., Freeman, H., Watson, T., Cameron, C., Sutherland, M., Effect of different milk removal strategies at weaning on feed intake and behavior of goat kids, Journal of Veterinary Behavior (2019), doi: https://doi.org/10.1016/j.jveb.2019.10.004. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier Inc. All rights reserved.
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Effect of different milk removal strategies at weaning on feed intake and behavior of
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goat kids
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Gosia Zobel, Hannah Freeman, Trevor Watson, Catherine Cameron, Mhairi Sutherland*
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AgResearch Ltd, Ruakura Research Centre, Hamilton 3214, New Zealand
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*Corresponding author. Tel.: +6478385503.
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E-mail address: [email protected] (M.Sutherland)
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Abstract
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Weaning from milk can be stressful for ruminants, particularly if the animals are not adjusted
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to consuming other feeds. The aim of this study was to investigate the effect of three different
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weaning strategies on feed intake and behavior of dairy goat kids. Forty-five, 3-month-old
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Saanen cross goats were allocated to one of three treatments (n = 3 pens/treatment, 5
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goats/pen): abrupt removal of milk (AB), gradual reduction in the concentration of milk
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replacer in the same volume of water (DILU) and gradual reduction in the volume of milk
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provided (VOL). Milk and pellet consumption were monitored for two days prior to treatment
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to establish baseline intake. Treatments began on d0. The gradual treatments were stepped
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down every 2 days over a 6-day period, while the abrupt treatment continued to receive
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baseline milk allowance. On d6, milk was no longer offered to all treatments. Measurements
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included weight gain, milk refusals and pellet intake, vocalizations, and rumination and lying
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behavior. Early in the weaning treatment period (d0 – d2), goats in the DILU pens had lower
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(P<0.05) average daily gains compared to AB and VOL treatments. Weaning treatment had
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no effect on milk refusals. DILU goats increased pellet intake earlier (d4 – d5) than other
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treatments, eating twice as much as AB and VOL (P<0.05), while immediately after milk was
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no longer offered (d6 – d7), VOL consumed less pellets than AB and DILU goats (P<0.05).
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All goats consumed the same amount of pellet by d8 – d9. Weaning treatment did not affect
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vocalizations; however, after weaning (d6 – d9), all treatments continued to vocalize after
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pellet delivery (P=0.003). Weaning treatment had no effect on rumination or lying behavior;
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rumination increased in all treatments. In summary, dilution of milk replacer negatively
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affected weight gain initially, however, these goats compensated by consuming more pellets.
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Goats weaned by gradually reducing milk volume did not increase pellet intake until milk
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was no longer provided, yet weight gain was not negatively affected. Four days following
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weaning from milk, no differences existed between the treatments, suggesting that none of
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the weaning strategies were better than the other when used in 12-week-old goats.
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Keywords: dairy; rumination; weaning; welfare; lying
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Introduction Weaning is a process that all mammals experience and typically involves both
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separation from the dam and loss of access to milk. In commercial dairy goat systems, kids
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are commonly separated from their dam immediately after birth and reared artificially until
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weaning from milk. This method conserves the dam’s milk and means that farmers have
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greater control over when and how kids are weaned. When kids are reared by their dams,
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weaning occurs gradually over time as the mother reduces her ongoing investment into her
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young, through less frequent and shorter suckling events (Bungo et al., 1998). This period of
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decreasing milk consumption for kids is coupled with increasing solid feed consumption, to
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compensate for the reduction in milk-based energy. However, in a commercial setting, kids
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may be weaned abruptly from milk – that is, milk is provided at a set volume (or ad libitum)
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and then one day not offered at all. A sudden change in diet, and removed opportunity to
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suckle, can be associated with a period of reduced or stagnated growth and a greater
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behavioral response (i.e., increased vocalizations and activity) (Budzynska and Weary, 2008;
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Jasper et al., 2008). Milk consumption prior to abrupt weaning may also discourage solid
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feed consumption before weaning. Ruminants are born with a non-functioning rumen, and
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solid feed is required to trigger rumen growth and maturation (Khan et al., 2011). If kids do
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not consume enough solid feed (e.g., grain, hay) before weaning, they may be unprepared for
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their post-weaning diet.
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Implementing a more gradual weaning method may better emulate natural weaning
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and therefore prepare kids to cope with this important transition. However, there have been
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few studies evaluating different weaning strategies in goat kids. Of these studies, several
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focus on weaning from dams (Ugur et al., 2007; Sporkmann et al., 2012) and therefore are
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not directly applicable to the dairy goat industry, which traditionally separates kids at an early
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age (Todd et al., in press). In one study where kids were artificially reared (i.e., away from
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their dam), gradual weaning from milk caused no apparent lag in growth (Magistrelli et al.,
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2013). While this study did find increased vocalizations, a possible indicator of hunger, there
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was no behavioral ethogram provided, the authors did not include an abrupt weaning control
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as a comparison, and there was no statistical analysis performed on any of the behavioral
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measures taken; these facts limit conclusions about welfare outcomes other than growth. A
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review by Lu and Potchoiba (1987) discusses the potential benefits of restricted milk feeding
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to encourage more efficient weaning onto solid feeds, however, they also do not consider
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measures of hunger.
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Studies evaluating weaning strategies for lambs have focused mainly on timing of
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separation from the dam rather than milk removal (Napolitano et al., 2018) and are therefore
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are not directly applicable to the dairy goat industry. Studies evaluating different weaning
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strategies in dairy calves may provide better guidance for good weaning strategies for goat
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kids; however, the existing work with calves provides conflicting results. Some previous
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research suggests that abruptly weaned calves lose weight after weaning (Budzynska and
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Weary, 2008; Sweeney et al., 2010) and that those weaned gradually continue to gain weight
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(Sweeney et al., 2010). Conversely, other work has found no weight loss after weaning, and
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no difference in weight gain or behavioral responses between gradual and abrupt methods
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(Jasper et al., 2008). Therefore, with literature for goats lacking, and conflicting literature for
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calves, there is a need to evaluate how different artificial weaning strategies affect the
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behavior and performance of goat kids.
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Studies investigating the effect of weaning age on goat performance have shown that
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kids can be weaned as early as 8 weeks of age without any long term detrimental effects on
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growth (Teh et al., 1984; Nagpal et al., 1995). However, it is common for New Zealand dairy
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goat farmers to wean later than this; a large multi-farm study found that median weaning age
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was 12.3 weeks of age (Todd et al., in press). The participants of the multi-farm study
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favored a target body weight (11/16 farmers), compared to age (2/16 farmers) or a
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combination of the two factors (3/16 farmers), when deciding when to wean their kids.
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Weaning strategies reported (unpublished data from above multi-farm study) by farmers
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include: 1) abrupt removal of milk, 2) gradually diluting the concentration of milk replacer,
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without decreasing the volume offered, and 3) decreasing the volume of milk offered to kids,
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in a step-wise fashion leading up to complete weaning. Therefore, the aim of this study was
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to evaluate the effect of three different weaning strategies on goat kid feed intake and
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behavior. The results were intended to provide science-based recommendations for dairy goat
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farmers targeting the 3-month weaning age.
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Materials and methods
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Animals and housing
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All procedures involving animals in this study were approved by the AgResearch
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Ruakura Animal Ethics Committee (Protocol no. 13685) under the New Zealand Animal
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Welfare Act 1999. The study was undertaken from October to November 2015 at the
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AgResearch Ruakura Research Centre, Hamilton, Waikato, New Zealand (latitude 37°47’S,
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longitude 175°19’E).
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Forty-five, female Saanen cross dairy goat kids were enrolled at approx. 11 weeks of
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age. Goats were sourced at 24 hours of age from two CAE-negative, commercial farms.
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Vaccinations were given when goats were approximately 2 days (Covexin 10, MSD Animal
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Health), 60 days (Covexin 10, MSD Animal Health) and 90 d (Leptoshield, Zeotis) old. They
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were disbudded at 20.8 ± 3.1 days of age (mean ± SD). Prior to enrolment, goats had
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unrestricted access to pasture and a run-in shed bedded with wood shavings. They were fed
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ad libitum milk replacer mixed according to package directions (i.e., 200 g replacer per kg of
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water; Anlamb, Fonterra Ltd., Auckland, New Zealand) via a 10-space kid feeder (Milk Bar,
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Waipu, New Zealand) refreshed twice daily, and also had ad libitum access to straw and
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water.
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Twelve days prior to the start of the study (d-14 to d-3), goats were moved into the
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research facility to allow for acclimation to housing and diet (described below). Goats were
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categorized by weight, and then randomly allocated from each category to the pens, ensuring
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there was a similar mean weight per pen (mean ± SE: 17.4 ± 1.4 kg; P > 0.1). The research
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building had solid concrete floors and solid walls (drywall on one side, and slatted wood on
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three sides). A raised metal platform was installed on top of the concrete (22.5 cm off the
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floor) onto which the experimental pens were constructed using steel jailer gates (Gallagher
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Group Ltd, Hamilton, New Zealand). Goats were moved into pens (n = 5 goats/pen)
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measuring 2.65 m x 3 m (1.6 m2/goat). Pens had plywood floors covered with wood shavings
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(approximately 10 mm particle size) at a depth of 15 cm. The pens had solid plywood sides
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separating them from other pens, so individuals in a pen could not interact with neighboring
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goats. Each pen contained a hay feeder (75 cm x 65 cm x 22 cm) and a meal feeder (77cm x
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31 cm, 20 L, McKee Plastics Ltd, Hamilton, NZ) that were attached to the side of the pen at a
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height of 128 cm and 42 cm above the floor, respectively. Lights were switched on at 0715 h
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and off at 1730 h. Milk continued to be mixed according to package directions and was split
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over two equal meals at 0800 h and 1630 h each day (approximately 0.9 kg/goat, which was
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in excess of consumption); it continued to be provided in the same kid feeder. Goats had ad
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libitum access to water, hay and straw. They also had ad libitum access to pellets (Dunstan
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Fibre Grow, Dunstan Nutrition Ltd, Hamilton, New Zealand) which was replaced during
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morning milk feeding and topped up if required in the afternoon.
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Experimental design
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Three weaning practices were compared: abrupt weaning from milk (AB), gradual
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reduction in the concentration of milk replacer while keeping the milk volume constant
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(DILU) and gradual reduction of the volume of milk provided (VOL). The reduction in the
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concentration of milk replacer (DILU) treatment was based on the concentration of milk
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replacer provided to goats in each DILU pen during the two baseline days (d-2 and d-1). The
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reduction in volume of milk (VOL) treatment was based on the average volume of milk
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consumed by goats in each VOL pen during the two baseline days (d-2 and d-1). For AB,
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there was no change in milk allowance from d0 to d5. Milk replacer concentration (DILU) or
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milk volume (VOL) were decreased, in a step-wise fashion (i.e., by 30%, every 2 days from
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d0 to d5), with complete weaning from milk on d6 (Table 1). Treatments were randomly
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assigned to the first three pens and then the order was replicated (Fig. 1) (n = 3
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pens/treatment, 5 goats/pen).
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Measures
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Weight gain and feed intake
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Goats were weighed by members of the research team that were blind to the
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treatments on d-8, d-1, d3, d6, d9 and d12 (Table 2), and these weights were used to calculate
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average daily gain (ADG; g/day/goat) between those time periods (baseline, early treatment,
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late treatment, early no milk, late no milk). The volume of milk provided to each pen was
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measured and weighed before and after each morning and afternoon feeding. Daily milk
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intake was calculated for each pen as weight of milk fed minus weight of milk refused.
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Similarly, each morning the remaining pellets from each pen were weighed before filling the
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troughs with a known quantity of pellets, and daily pellet intake were calculated. Milk and
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pellet refusals and intakes were divided by five to allow for reporting on a per goat basis.
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Vocalizations Vocalizations could not be observed from the video footage as it was not possible to
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know which pen the vocalizations were emanating from, therefore they were recorded via
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live observations, beginning two days prior to the start of treatments and then throughout the
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treatment period (Table 2). The frequency of vocalizations emanating from each pen was
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recorded for 1 h prior to feeding (morning: 0700-0800 h, afternoon: 1500-1600 h) and 1 h
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after feeding (morning: 0830-0930 h, afternoon: 1630-1730 h) with a 30-minutes pause for
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feeding (0800-0830 h and 1600-1630 h). These observations were done on a pen basis as it
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was not always possible to know which goat in each pen was vocalizing. Elevated platforms
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were placed outside of the experimental pens to minimize disturbance to the goats and to
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allow for a clear view of two pens at all times (Fig. 1). To further reduce the chance of goats
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vocalizing because of human presence, observers sat quietly and motionless for 15 minutes
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prior to beginning each observation. At each observation session, five observers watched two
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pens each, resulting in one pen always being watched in duplicate. The duplicate observation
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was used in a REML model with observer as a fixed effect, and observation session as a
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random effect to confirm inter-observer reliability. Observers were blind to treatments and
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rotated positions at the next observation session.
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Rumination behavior
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Behavior was recorded continuously in real time (30 frames/s) using overhead
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cameras (DS-2CD2332-I, Hikvision, Hangzhou, China) attached to the ceiling of the facility.
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The cameras’ built-in infrared light enabled night recordings to be carried out. Rumination
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behavior was measured using Premiere Pro software (Adobe, USA). Two goats per pen were
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pseudo-randomly selected (i.e., randomly selected, except that if the selected goat was brown
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or black, which precluded reliable monitoring of chewing activity at night, it was excluded
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and replaced by a randomly selected white goat). These focal goats were then continuously
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observed for 24 h on d-1 (baseline) and d8 (at which time all treatments had been without
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milk for 3 days) (Table 2). Rumination involves regurgitation, chewing and subsequent
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swallowing of an individual bolus. Rumination times were taken from the start of each bolus
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regurgitation until swallowing (Hooper and Welch, 1983; Schirmann et al., 2009). These
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points were defined as follows: 1) Onset: Individual’s cheeks fill. If cheek fill is not visible
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(i.e., because goat moves its head out of from camera view) then onset is coded beginning at
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first jaw movement, or ears beginning to move up and down as a result of jaw movement.
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Preference of onset signal is in the following order: cheek fill > first jaw movement > ear
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movement. 2) End: Individual swallows bolus. If swallowing motion is not visible, then end
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is coded from final jaw movement, or ears ceasing movement up and down as a result of jaw
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movement ceasing. Preference of signal is in the following order: swallowing > final jaw
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movement > ceasing ear movement. This definition was validated through a small sampling
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of regurgitation times (two boli from five randomly selected goats), where the time delay
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between these signals was determined for both onset and end of rumination. The total
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difference never exceeded 1 s, which was the smallest unit of time used in this study. One
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observer recorded all rumination behavior and was blind to treatment; intra-observer
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reliability was calculated using total rumination time for two goats for 2 hours. We report the
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number of regurgitated boli (number/day), the chewing time of each boli (seconds/boli), and
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the inter-boli length (seconds between boli); calculations using these values provide
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rumination bouts (number/day), rumination bout length (minutes/bout), boli regurgitated per
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bout (number/bout) and total rumination time (hour/day). A rumination bout was defined as a
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period of successive bolus regurgitations followed by a period of at least 60 seconds where
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no regurgitations occurred. The length of each rumination bout was the sum of chewing and
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the time between chewing within a single bout. Total rumination duration was taken as the
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sum of the time of each rumination bout. Any rumination which was interrupted by the focal
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individual moving out of sight was removed from calculations of the chewing time and the
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inter-boli length (<1% of all regurgitations).
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Lying behavior
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Lying and standing behavior was recorded continuously using HOBO pendant G data
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loggers (64k, Onset Computer Corporation, Bourne, MA, USA) set at 1-min intervals
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recording the X and Z axes for the duration of the trial (Table 2). The loggers were fitted into
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purpose made fabric pouches which were attached on the lateral side of the right hind leg
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above the metatarsophalangeal joint. Accelerometers were placed vertically on the leg such
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that the x-axis ran perpendicular to the ground, pointing in the dorsal direction and the z-axis
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ran parallel to the ground, pointing toward the mid-plane of the goat. Accelerometers were
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initialized and downloaded using Onset HOBOware Pro software (Onset Computer
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Corporation, version 3.7.2). Raw g-forces were converted into binary values (e.g., lying = 0,
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standing = 1) and daily summaries of lying time (h/d) and lying bout frequency (no. bouts/d)
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were calculated in SAS 9.3 (SAS Institute Inc., Cary, NC, USA) using a code designed for
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this purpose (AWP UBC, 2016) and validated for use in goats (Zobel et al., 2015). Lying
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behavior was paired with rumination behavior, and therefore only the data collected by the
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loggers on the focal goats was used in analysis (n = 3 treatments/pen with 2 focal goats per
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pen).
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Statistical analysis Data were analyzed by analysis of variance using GenStat statistical software
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(Version 18, VSN International, UK). There were three randomized replicated pens, each
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containing five goats, for each of the three weaning treatments (AB, DILU and VOL). All
11
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pens were included in the analysis of each variable, with the exception of pen eight for
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rumination, where a camera fault prevented accurate scoring of regurgitation, and pen nine
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for milk consumption, where the nipples of the milk feeder were adjusted during the baseline
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period. Since residual plot inspection showed that all data met the normality assumptions, no
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transformations of the data were performed. A repeated measures Residual Maximum
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Likelihood (REML) analysis (Patterson and Thompson, 1971) was run for each outcome
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variable (ADG, change in milk refusal, change in pellet intake, vocalizations, rumination
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behavior, and lying behavior), fitting weaning treatment, period and the interaction between
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treatment and period as fixed effects, and pen, and goat within pen, as random effects. Mean
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separation was assessed by Fisher’s protected Least Significant Difference (LSD). The period
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effect in each model was based on when sampling occurred for each outcome variable. ADG
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was compared during the following periods: baseline (d-8 to d-1), early treatment (d-1 to d3),
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late treatment (d3 to d6), early no milk (d6 to d9) and late no milk (d9 to d12) for each
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treatment. For change in milk refusals and pellet intake, the 2-day weaning step down periods
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were compared (d0 to d1, d2 to d3, d4 to d5, d6 to d7 and d8 to d9) for each treatment. For
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vocalizations there were two periods: milk feeding (d0 to d5) and no milk (d6 to d8), and for
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rumination behavior and lying behavior, there were also two periods: baseline (d-1: one day
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prior to the start of the weaning treatments) and 3 days after all treatments had not received
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milk (d8) compared for each treatment. Each outcome variable was averaged according to
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their respective period before testing in the model. Results are reported as mean ± SED,
265
unless otherwise stated.
266 267
Results
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Behavioral observation reliability
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No differences were found between observers for scoring vocalizations before and
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after feeding throughout the entire study (P = 0.48). For rumination behavior, good intra-
271
observer reliability was achieved prior to the beginning of observations (weighted kappa, κw
272
= 0.89).
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Average daily gain (ADG)
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Prior to weaning (d-8 to d-1), ADG was similar among all treatments (0.3, 0.2, 0.2 ±
276
0.06 kg/d/goat for AB, DILU and VOL treatments, respectively; P = 0.641). During the first
277
3 days of the treatment period (d0 – d2), goats in the DILU pens had lower (P < 0.05) ADG
278
(0.1 ± 0.07 kg/d/goat) compared to AB (0.3 ± 0.07 kg/d/goat) and VOL (0.2 ± 0.07 kg/d/goat)
279
treatments (treatment effect: P = 0.01). During the subsequent periods, ADG did not differ (P
280
> 0.05) among treatments.
281 282 283
Milk and pellet intake There was no treatment effect on the change in milk refused by goats over the 6-day
284
weaning treatment period (milk refused [change from baseline]: -196, -274, -103 ± 116.6
285
g/d/goat for AB, DILU and VOL treatments, respectively; P = 0.430). However, there was an
286
effect of period (P < 0.001); during step 1 (d0 – d1), there were less refusals compared to the
287
other weaning steps (milk refused [change from baseline]: -98, -227, -249 ± 25.6 g/d/goat for
288
step 1, step 2 (d2 – d3) and step 3 (d4 – d5), respectively).
289
There was no effect of treatment on change in pellet intake (P = 0.617), however there
290
was an effect of weaning step (P < 0.001) and a step by treatment interaction (P = 0.003; Fig.
291
2). During steps 1 and 2 (d0 – d4) when milk was still being offered, there was no difference
292
among AB, DILU and VOL treatments in change in pellet intake (P = 0.11). However, during
293
step 3 (d4 – d5), DILU goats were eating twice as much pellets as AB and VOL goats (P <
13
294
0.05). During step 4 (d6 – d7) after milk was no longer offered, VOL goats consumed less
295
pellets than AB and DILU goats (P < 0.05). There was no difference (P > 0.1) in change in
296
pellet intake among treatments during step 5 (d8 – d9).
297 298
Behavior
299
There were no treatment differences for vocalizations before and after feeding (P =
300
0.8), nor was there a treatment by period interaction (P = 0.7). However, after milk was no
301
longer offered (d6 – d9), compared to when they had milk all treatments dramatically
302
increased their vocalizations in the observation session after feeding (P = 0.003); no
303
difference was seen in the observation session before pellet feeding (P = 0.25) (Fig. 3).
304
Abruptly weaned goats performed more rumination bouts on d8 (when milk was no
305
longer provided) compared to d-1, but the frequency of rumination bouts was similar on d-1
306
and d8 for DILU and VOL goats (treatment by period effect: P = 0.019; Fig. 4). Compared to
307
baseline, on d8 goats ruminated for longer, rumination bouts were longer, more boli were
308
regurgitated over the day as well as within individual bouts, the time spent chewing during
309
individual boli increased, and the time between regurgitated boli decreased (Table 3).
310
Weaning treatment had no effect (P > 0.1) on lying times and lying bout frequency,
311
nor was there a treatment by period interaction (P > 0.1). However, once milk was no longer
312
offered (d8), the proportion of time goats spent lying and ruminating concurrently increased
313
(Table 3; P < 0.001).
314 315 316
Discussion Weaning goats by diluting the concentration of milk replacer resulted in goats
317
consuming more pellets prior to complete milk removal compared to the other weaning
318
treatments evaluated. This increase in pellet consumption followed the initial lower ADG
14
319
recorded for this treatment, hence it is likely that these goats consumed more pellets to
320
compensate for the reduced energy intake provided by the diluted milk. A similar pattern was
321
noted in calves, where animals that received gradually less concentrated milk, consumed
322
more starter diet prior to milk removal compared to calves given access to non-diluted milk
323
(Jasper et al., 2008). Interestingly, goats gradually weaned by reducing the volume of milk
324
replacer did not appear to similarly compensate for the reduced energy intake by consuming
325
more pellets, which is contradictory to studies in dairy calves (reviewed in Khan et al., 2011).
326
Nonetheless, in the current study the impact of treatment was minimal, and at weaning all
327
treatments had similar weight gains, therefore none of the treatments appeared to be superior
328
to the others based on performance measures (e.g., intake and growth).
329
After complete milk removal, it took longer for goats receiving less milk (VOL) prior
330
to weaning to start consuming pelleted feed, compared to the other two treatments. It is
331
unclear why gradually reducing milk volume did not stimulate kids to consume more pelleted
332
feed, however ADG was not negatively impacted in these goats, suggesting that they were
333
still receiving adequate energy to maintain normal growth. Different weaning practices may
334
cause different sensations of hunger. In human trials, viscosity affected satiety; a thick liquid
335
meal left people feeling more full and satiated than a less viscous meal (Camps et al., 2016).
336
Therefore, goats that received the same concentration of milk replacer as they received prior
337
to the start of the weaning treatments, albeit at a reduced volume, may have felt fuller after
338
feeding due to its greater viscosity than those that received a diluted and less viscous meal.
339
Alternatively, goats receiving less milk could have satiated their remaining hunger by
340
increasing the consumption of hay and straw rather than pellets. In the present study, we were
341
unable to monitor the consumption of hay and straw; this was a limitation of the study design,
342
and thus we are unable to support this speculation.
15
343
Complete removal of milk resulted in kids vocalizing more after weaning and these
344
results are similar to other reports in kids (Magistrelli et al., 2013) and calves (Budzynska and
345
Weary, 2008; Jasper et al., 2008). However, in the present study weaning strategy did not
346
affect the frequency of vocalizations in response to complete milk removal. Magistrelli et al.
347
(2013) suggested that kids gradually given less milk prior to weaning only vocalized more
348
when the milk was completely removed from their diet; unfortunately, their results were only
349
descriptive. Calves that were gradually weaned by diluting the milk with water, vocalized as
350
much as abruptly weaned calves, when the milk was completely removed (Jasper et al.,
351
2008). Therefore, it is unsurprising that gradually reducing the volume or the concentration of
352
milk in the diet in the present study also did not prepare goats for complete milk removal. It
353
is worth noting that in the present study, while treatment groups did not have visual or tactile
354
contact with one another, they could hear one another; therefore, it is possible one treatment
355
vocalizing triggered the others to vocalize as well (Watts and Stookey, 2000).
356
Jasper et al. (2008) suggested that calves may vocalize more after weaning because
357
they are experiencing withdrawal as a result of no longer being able to suckle, rather than due
358
to the removal of milk from their diet per se; this is suggested because suckling involves the
359
opiate system. Replacing milk with warm water caused calves to vocalize less in response to
360
complete milk removal, but did not completely prevent the vocal response to weaning
361
(Budzynska and Weary, 2008; Jasper et al., 2008). Therefore, in future studies it would be
362
worth evaluating the mechanisms that are involved in the behavioral response to weaning
363
(e.g., hunger or suckling withdrawal), so that appropriate alternative weaning strategies can
364
be developed that satisfy the behavioral needs of goats. For example, replacing milk with
365
warm water would continue a goat’s ability to suckle, and perhaps help goats transition better
366
from a milk-based to a completely solid feed diet.
16
367
Adult goats spend 25-30% of their day ruminating (6.1 hours/day, Domingue et al.,
368
1991; 7.2 hours/day, Von Engelhardt et al., 2006; Jalali et al., 2012). In the present study,
369
removal of milk access resulted in a dramatic increase in time spent ruminating. Just 3 days
370
after milk removal, kids were ruminating at levels over 70% of what has previously been
371
reported for adult goats. Similarly to the current trial, 3 month old goat kids were previously
372
reported ruminating for 4.7 ± 0.5 hours/day (Hooper and Welch, 1983); interestingly, those
373
kids were less than half the body weight of the kids in the current study, suggesting age,
374
rather than body weight, plays a major role in the development of rumination. Treatment did
375
not impact the majority of the rumination behavior observed. Goats were enrolled in this
376
study at approximately 3 months of age; this is similar to the reported weaning age on New
377
Zealand dairy goat farms (Todd et al., in press). However, it has been reported that goat kids
378
may be weaned as young as 5 week of age (Lu and Potchoiba, 1988), and therefore we
379
suggest that age played a significant factor in the lack of treatment differences in the current
380
study. Even prior to weaning, kids were ruminating for over 3 hours/day. It is possible that if
381
the kids were younger, the treatment which promoted increased pellet intake (e.g., reduced
382
volume) would have had more of an impact on rumination. Indeed, in calves it has been
383
shown that rumination behavior is affected dramatically by age at weaning (e.g., a 4-fold
384
increase in rumination when calves were 8 week old vs. 6 week old; Eckert et al., 2015).
385
However, the aim of this study was to evaluate different weaning practices in 12-week-old
386
goat kids as this age is relevant to the New Zealand dairy goat industry.
387
It has been reported that rumination may occur during standing and walking (goats,
388
Paulo and Lopes, 2014; cows, Schirmann et al., 2009; bighorn sheep, Moquin et al., 2010).
389
We found that goats in the current trial spent very little time ruminating while upright (i.e.,
390
less than 1% of the day). Indeed, goats spent almost 20% of their lying time ruminating after
391
weaning. We suggest that this may be a function of the housing environment, which provided
17
392
sufficient space for the goats, but was not enriched in ways that might promote activity, and
393
therefore the goats spent up to 70% of their time lying down.
394
In conclusion, continued vocalization in the 3 day period after milk was no longer
395
provided suggests that the goats had not yet adjusted to the change in routine. However,
396
pellet intake and ADG were similar among the weaning treatments, suggesting that none of
397
the weaning strategies evaluated were better to the other when weaning 12-week-old goats
398
when considering performance measures. Therefore, if the goats are adjusted to consuming
399
hard feeds, any of these weaning strategies could be recommended to dairy goat farms when
400
weaning at this age.
401 402 403 404
Conflict of interest statement None of the authors has any financial or personal relationships that could inappropriately influence or bias the content of the paper.
405 406 407
Acknowledgements The authors gratefully acknowledge the assistance from AgResearch staff and
408
students (Tania Blackmore, Rebecca Yeates, Betina Bruce, Briar Roberston and Melissa
409
Hempstead). Funding was provided by the New Zealand Ministry of Business, Innovation
410
and Employment (C10X1307), as well as the Dairy Goat Co-operative (NZ) Ltd. We also
411
would like to thank NZ goat farmers for their input into this project.
412 413 414 415
Ethical statement All procedures involving animals were approved by the AgResearch Animal Ethics Committee (protocol no. 13685) under the New Zealand Animal Welfare Act 1999.
416 417 18
418
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AWP UBC., 2016. UBC Animal Welfare Program: SOP - HOBO Data Loggers, SAS CODE
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Version 1. 14–22.
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Budzynska, M., Weary, D.M., 2008. Weaning distress in dairy calves: Effects of alternative
422
weaning procedures. Appl. Anim. Behav. Sci. 112, 33–39.
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Bungo, T., Shimojo, M., Nakano, Y., Okano, K., Masuda, Y., Goto, I., 1998. Relationship
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between nursing and suckling behaviour in Tokara native goats. Appl. Anim. Behav. Sci. 59,
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357–362.
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Camps, G., Mars, M., de Graaf, C., Smeets, P.A.M., 2016. Empty calories and phantom
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fullness: a randomized trial studying the relative effects of energy density and viscosity on
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gastric emptying determined by MRI and satiety. Am. J. Clin. Nutr. 104, 73–80.
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Domingue, B.M., Dellow, D.W., Barry, T.N., 1991. The efficiency of chewing during eating
430
and ruminating in goats and sheep. Brit. J. Nutr. 65, 355–63.
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Eckert, E., Brown, H.E., Leslie, K.E., DeVries, T.J., Steele, M.A., 2015. Weaning age affects
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growth, feed intake, gastrointestinal development, and behavior in Holstein calves fed an
433
elevated plane of nutrition during the preweaning stage. J. Dairy Sci. 98, 6315–6326.
434
von Engelhardt, W., Haarmeyer, P., Kaske, M., Lechner-Doll., M 2006. Chewing activities
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and oesophageal motility during feed intake, rumination and eructation in camels. J. Comp.
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Physiol. B: Biochem. Syst. Environ. Physiol. 176, 117–124.
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Hooper, A.P., Welch, J.G., 1983. Chewing efficiency and body size of kid goats. J. Dairy Sci.
438
66, 2551–2556.
19
439
Jalali, A.R., Nørgaard, P., Weisbjerg, M.R., Nielsen, M.O., 2012. Effect of forage quality on
440
intake, chewing activity, faecal particle size distribution, and digestibility of neutral detergent
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fibre in sheep, goats, and llamas. Small Rumin. Res. 103, 143–151.
442
Jasper, J., Budzynska, M., Weary, D.M., 2008. Weaning distress in dairy calves: Acute
443
behavioural responses by limit-fed calves. Appl. Anim. Behav. Sci. 110, 136–143.
444
Khan, M.A., Weary, D.M., von Keyserlingk, M.A.G., 2011. Invited review: Effects of milk
445
ration on solid feed intake, weaning, and performance in dairy heifers. J. Dairy Sci. 94, 1071–
446
1081.
447
Lu, C.D., Potchoiba, M.J., 1988. Milk feeding and weaning of goat kids - A review. Small
448
Rumin. Res. 1, 105–112.
449
Magistrelli, D., Aufy, A.A., Pinotti, L., Rosi, F., 2013. Analysis of weaning-induced stress in
450
Saanen goat kids. J. Anim. Physiol. Anim. Nutr. 97, 732–739.
451
Moquin, P., Curry, B., Pelletier, F., Ruckstuhl, K.E., 2010. Plasticity in the rumination
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behaviour of bighorn sheep: Contrasting strategies between the sexes? Anim. Behav. 79,
453
1047–1053.
454
Nagpal, A.K., Singh, D., Prasad, V.S.S., Jain, P.C., 1995. Effect of weaning age and feeding
455
system on growth performance and carcass traits of male kids in three breeds in India. Small
456
Rumin. Res. 17, 45-50.
457
Napolitano, F., De Rosa, G., Sevi, A., 2008. Welfare implications of artificial rearing and
458
early weaning in sheep. Appl. Anim. Behav. Sci. 110, 58-72.
459
Paulo, J.L.D.A., Lopes, F.D.A., 2014. Daily activity patterns of Saanen goats in the semi-arid
460
northeast of Brazil. Revista Brasileira de Zootecnia 43, 464–470.
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461
Schirmann, K., von Keyserlingk, M.A.G., Weary, D.M., Veira, D.M., Heuwieser, W., 2009.
462
Technical note: Validation of a system for monitoring rumination in dairy cows. J. Dairy Sci.
463
92, 6052–6055.
464
Sporkmann, K., Georg, H., Bender, S., Ude, G., 2012. Heart rate variability of goat kids to
465
evaluate stress in different weaning situations. Landtechnik 67, 417–420.
466
Sweeney, B.C., Rushen, J., Weary, D.M., de Passillé, A.M., 2010. Duration of weaning,
467
starter intake, and weight gain of dairy calves fed large amounts of milk. J. Dairy Sci. 93,
468
148–152.
469
Teh, TH., Potchoiba, M.J., Escobar, E.N., and Lu, C.D. 1984. Weaning methods of goat kids.
470
J. Dairy Sci., 67: Suppl. 1: 137.
471
Todd, C., Bruce, B., Deeming, L. Zobel, G., Short communication: Survival of replacement
472
kids from birth to mating on commercial dairy goat farms in New Zealand. J. Dairy Sci. in
473
press.
474
Ugur, F., Atasoglu, C., Tolu, C., Diken, F., Pala, A., 2007. Effects of different weaning
475
programs on growth of Saanen kids. Anim. Sci. J. 78, 281–285.
476
Watts, J.M., Stookey, J.M., 2000. Vocal behaviour in cattle: The animal’s commentary on its
477
biological processes and welfare. Appl. Anim. Behav. Sci. 67, 15–33.
478
Zobel, G., Weary, D.M., Leslie, K., Chapinal, N., von Keyserlingk, M.A.G., 2015. Technical
479
note: Validation of data loggers for recording lying behavior in dairy goats. J. Dairy Sci. 98,
480
1082–1089.
481
21
482
Table 1. Description of weaning treatments illustrating the percentage of milk volume (AB and VOL treatments) or concentration of milk
483
replacer (VOL treatment) provided to goats in relation to the baseline pre-weaning treatment period. Milk replacer concentration (DILU) or milk
484
volume (VOL) were decreased in step-wise fashion every 2 days, leading up to complete weaning on day 6. -2
-1 Baseline
Treatment1 AB
100%
100%
DILU
100%
100%
VOL
100%
100%
0
1
Step 1 100% 100 % 70% 70 % 70% 70 %
Days relative to treatment 2 3 4 5 Treatment Step 2 Step 3 100% 100% 100% 100%
6 No milk 0%
50%
50%
20%
20%
0%
50%
50%
20%
20%
0%
485 486
1
487
but milk volume remained consistent) and VOL (volume of milk was reduced every 2 days from d0 to d5).
Treatments: AB (no change in milk allowance from d0 to d5), DILU (concentration of milk replacer was reduced every 2 days from d0 to d5,
22
488
Table 2. Timeline of measurements. The days that measures were recorded are shaded. Day relative to treatment -12 -11 -10 -9 -8 -7 -6 -5 -4 -3
Acclimation
-2
-1
Baseline
0
1
2
3
Treatment
4
5
6
7
8
9
10
11
12
No Milk
Weight Milk intake Pellet intake Vocalizations Rumination Lying
489 490 491
23
492
Table 3. Rumination behavior and the proportion of the day focal goats spent lying and
493
standing while ruminating or not (n = 3 pens/treatment, 2 goats monitored/pen). Daily
494
behaviors were measured during the baseline period (d-1: one day prior to the start of the
495
weaning treatments) and after all treatments had not received milk for 3 days (d8). Period1 Baseline
No milk offered
SED
P-value
(d-1)
(d8)
Time (hours(h)/day (d))
3.5
5.2
0.2
<0.001
Bouts (number (n)/d)
26.2
30.9
1.3
0.002
Bout length (minutes (min)/bout)
8.5
10.6
0.6
0.005
Boli regurgitated (n/d)
304
441
21.7
<0.001
Time spent chewing (seconds
31.5
33.7
0.5
<0.001
Inter-boli length (s between boli)
11.1
9.6
0.4
0.003
Boli regurgitated (n/bout)
11.9
14.9
0.9
0.007
Lying, while ruminating
10.8
17.9
1.0
< 0.001
Lying, while not ruminating
52.4
45.1
1.1
< 0.001
Standing, while ruminating
0.4
0.9
0.3
0.05
Standing, not ruminating
36.4
36.2
0.6
0.6
Rumination
(s)/boli)
Lying and standing behavior (%/d)
496
1
497
treatment and period were found, therefore only effect of period is reported.
With exception of rumination bouts, no treatment effect and no interaction between
498 499 24
500
List of figure captions
501
Figure 1. Pen layout. Treatment was randomly selected for the first three pens, and then
502
allocated to the remaining pens in replicated order. Trapezoids represent observer locations
503
for vocalization observations (observer location 2 and 3 monitored one of the same pens,
504
providing daily inter-observer reliability).
505 506
Figure 2. Mean (± SED) change in pellet intake (g/d/goat) from baseline during a 6-day
507
weaning period (d0 – d5) that consisted of three, 2-day step changes, and a 4-day period (d6 –
508
d9) where no treatments received milk (n = 3 pens/treatment, 5 goats/pen). Treatments: AB:
509
no change in milk allowance from d0 – d5; DILU: concentration of milk replacer reduced
510
every 2 days from d0 – d5, with constant volume of water; VOL: volume of milk reduced
511
every 2 days from d0 – d5. Milk was removed from all treatments on d6. *DILU differ from
512
AB and VOL treatments at P < 0.05. †VOL differ from AB and DILU treatments at P < 0.05.
513 514
Figure 3. Mean (± SED) number of vocalizations (no./pen/period) performed by goats (n = 3
515
pens/treatment, 5 goats/pen) over a 1 h period before and 1 h period after feeding, when milk
516
was still being provided (d0 – d5) and when milk was no longer offered (d6 – d8). No
517
treatment effect and no interaction between treatment and period were found, therefore only
518
effect of period is reported. *Means within observation period differ at P < 0.05.
519 520
Figure 4. Mean (± SED) rumination bouts (no./d/goat) before treatments began (d-1) and 3
521
days after milk was no longer offered (d8) (n = 3 pens/treatment, 2 goats monitored/pen).
522
Treatments: AB: no change in milk allowance from d0 – d5; DILU: concentration of milk
523
replacer reduced every 2 days from d0 – d5, with constant volume of water; VOL: volume of
25
524
milk reduced every 2 days from d0 – d5. Milk was removed from all treatments on d6.
525
*Means within treatment differ at P < 0.05.
526
26
527
Figure 1.
528 529
27
Figure 2. Change in pellet intake from baseline (g/d/goat)
530 531
Milk
600
No milk †
500
* 400 300 200 100 0 0-1 -100
2-3
4-5
6-7
8-9
Days relative to start of weaning treatments AB
DILU
VOL
532 533 534
28
535
Figure 3. Milk
No milk
Vocalizations (no./pen/period)
140
*
120 100 80 60 40 20 0 Before Feeding -20
After Feeding
Observation period
536 537 538
29
539
Figure 4. Milk
Rumination bouts (no./d/goat)
40
No milk
*
35 30 25 20 15 10 5 0 AB
DILU
VOL
Weaning treatment
540 541 542
30
Highlights •
Gradual reduction in milk concentration caused goats to initially gain less weight
•
Gradual reduction in milk volume caused goats to consume less pellets initially
•
After milk removal, all weaning treatments vocalized more after pellet feeding
•
None of the weaning strategies evaluated were superior than the others
S1558-7878(19)30063-2
DOI:
https://doi.org/10.1016/j.jveb.2019.10.004
Reference:
JVEB 1279
To appear in:
Journal of Veterinary Behavior
Received Date: 11 March 2019 Revised Date:
4 June 2019
Accepted Date: 1 October 2019
Please cite this article as: Zobel, G., Freeman, H., Watson, T., Cameron, C., Sutherland, M., Effect of different milk removal strategies at weaning on feed intake and behavior of goat kids, Journal of Veterinary Behavior (2019), doi: https://doi.org/10.1016/j.jveb.2019.10.004. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier Inc. All rights reserved.
1
Effect of different milk removal strategies at weaning on feed intake and behavior of
2
goat kids
3 4 5
Gosia Zobel, Hannah Freeman, Trevor Watson, Catherine Cameron, Mhairi Sutherland*
6 7 8
AgResearch Ltd, Ruakura Research Centre, Hamilton 3214, New Zealand
9 10 11 12 13
*Corresponding author. Tel.: +6478385503.
14
E-mail address: [email protected] (M.Sutherland)
15 16
1
17
Abstract
18
Weaning from milk can be stressful for ruminants, particularly if the animals are not adjusted
19
to consuming other feeds. The aim of this study was to investigate the effect of three different
20
weaning strategies on feed intake and behavior of dairy goat kids. Forty-five, 3-month-old
21
Saanen cross goats were allocated to one of three treatments (n = 3 pens/treatment, 5
22
goats/pen): abrupt removal of milk (AB), gradual reduction in the concentration of milk
23
replacer in the same volume of water (DILU) and gradual reduction in the volume of milk
24
provided (VOL). Milk and pellet consumption were monitored for two days prior to treatment
25
to establish baseline intake. Treatments began on d0. The gradual treatments were stepped
26
down every 2 days over a 6-day period, while the abrupt treatment continued to receive
27
baseline milk allowance. On d6, milk was no longer offered to all treatments. Measurements
28
included weight gain, milk refusals and pellet intake, vocalizations, and rumination and lying
29
behavior. Early in the weaning treatment period (d0 – d2), goats in the DILU pens had lower
30
(P<0.05) average daily gains compared to AB and VOL treatments. Weaning treatment had
31
no effect on milk refusals. DILU goats increased pellet intake earlier (d4 – d5) than other
32
treatments, eating twice as much as AB and VOL (P<0.05), while immediately after milk was
33
no longer offered (d6 – d7), VOL consumed less pellets than AB and DILU goats (P<0.05).
34
All goats consumed the same amount of pellet by d8 – d9. Weaning treatment did not affect
35
vocalizations; however, after weaning (d6 – d9), all treatments continued to vocalize after
36
pellet delivery (P=0.003). Weaning treatment had no effect on rumination or lying behavior;
37
rumination increased in all treatments. In summary, dilution of milk replacer negatively
38
affected weight gain initially, however, these goats compensated by consuming more pellets.
39
Goats weaned by gradually reducing milk volume did not increase pellet intake until milk
40
was no longer provided, yet weight gain was not negatively affected. Four days following
2
41
weaning from milk, no differences existed between the treatments, suggesting that none of
42
the weaning strategies were better than the other when used in 12-week-old goats.
43 44
Keywords: dairy; rumination; weaning; welfare; lying
45
3
46 47
Introduction Weaning is a process that all mammals experience and typically involves both
48
separation from the dam and loss of access to milk. In commercial dairy goat systems, kids
49
are commonly separated from their dam immediately after birth and reared artificially until
50
weaning from milk. This method conserves the dam’s milk and means that farmers have
51
greater control over when and how kids are weaned. When kids are reared by their dams,
52
weaning occurs gradually over time as the mother reduces her ongoing investment into her
53
young, through less frequent and shorter suckling events (Bungo et al., 1998). This period of
54
decreasing milk consumption for kids is coupled with increasing solid feed consumption, to
55
compensate for the reduction in milk-based energy. However, in a commercial setting, kids
56
may be weaned abruptly from milk – that is, milk is provided at a set volume (or ad libitum)
57
and then one day not offered at all. A sudden change in diet, and removed opportunity to
58
suckle, can be associated with a period of reduced or stagnated growth and a greater
59
behavioral response (i.e., increased vocalizations and activity) (Budzynska and Weary, 2008;
60
Jasper et al., 2008). Milk consumption prior to abrupt weaning may also discourage solid
61
feed consumption before weaning. Ruminants are born with a non-functioning rumen, and
62
solid feed is required to trigger rumen growth and maturation (Khan et al., 2011). If kids do
63
not consume enough solid feed (e.g., grain, hay) before weaning, they may be unprepared for
64
their post-weaning diet.
65
Implementing a more gradual weaning method may better emulate natural weaning
66
and therefore prepare kids to cope with this important transition. However, there have been
67
few studies evaluating different weaning strategies in goat kids. Of these studies, several
68
focus on weaning from dams (Ugur et al., 2007; Sporkmann et al., 2012) and therefore are
69
not directly applicable to the dairy goat industry, which traditionally separates kids at an early
70
age (Todd et al., in press). In one study where kids were artificially reared (i.e., away from
4
71
their dam), gradual weaning from milk caused no apparent lag in growth (Magistrelli et al.,
72
2013). While this study did find increased vocalizations, a possible indicator of hunger, there
73
was no behavioral ethogram provided, the authors did not include an abrupt weaning control
74
as a comparison, and there was no statistical analysis performed on any of the behavioral
75
measures taken; these facts limit conclusions about welfare outcomes other than growth. A
76
review by Lu and Potchoiba (1987) discusses the potential benefits of restricted milk feeding
77
to encourage more efficient weaning onto solid feeds, however, they also do not consider
78
measures of hunger.
79
Studies evaluating weaning strategies for lambs have focused mainly on timing of
80
separation from the dam rather than milk removal (Napolitano et al., 2018) and are therefore
81
are not directly applicable to the dairy goat industry. Studies evaluating different weaning
82
strategies in dairy calves may provide better guidance for good weaning strategies for goat
83
kids; however, the existing work with calves provides conflicting results. Some previous
84
research suggests that abruptly weaned calves lose weight after weaning (Budzynska and
85
Weary, 2008; Sweeney et al., 2010) and that those weaned gradually continue to gain weight
86
(Sweeney et al., 2010). Conversely, other work has found no weight loss after weaning, and
87
no difference in weight gain or behavioral responses between gradual and abrupt methods
88
(Jasper et al., 2008). Therefore, with literature for goats lacking, and conflicting literature for
89
calves, there is a need to evaluate how different artificial weaning strategies affect the
90
behavior and performance of goat kids.
91
Studies investigating the effect of weaning age on goat performance have shown that
92
kids can be weaned as early as 8 weeks of age without any long term detrimental effects on
93
growth (Teh et al., 1984; Nagpal et al., 1995). However, it is common for New Zealand dairy
94
goat farmers to wean later than this; a large multi-farm study found that median weaning age
95
was 12.3 weeks of age (Todd et al., in press). The participants of the multi-farm study
5
96
favored a target body weight (11/16 farmers), compared to age (2/16 farmers) or a
97
combination of the two factors (3/16 farmers), when deciding when to wean their kids.
98
Weaning strategies reported (unpublished data from above multi-farm study) by farmers
99
include: 1) abrupt removal of milk, 2) gradually diluting the concentration of milk replacer,
100
without decreasing the volume offered, and 3) decreasing the volume of milk offered to kids,
101
in a step-wise fashion leading up to complete weaning. Therefore, the aim of this study was
102
to evaluate the effect of three different weaning strategies on goat kid feed intake and
103
behavior. The results were intended to provide science-based recommendations for dairy goat
104
farmers targeting the 3-month weaning age.
105 106
Materials and methods
107
Animals and housing
108
All procedures involving animals in this study were approved by the AgResearch
109
Ruakura Animal Ethics Committee (Protocol no. 13685) under the New Zealand Animal
110
Welfare Act 1999. The study was undertaken from October to November 2015 at the
111
AgResearch Ruakura Research Centre, Hamilton, Waikato, New Zealand (latitude 37°47’S,
112
longitude 175°19’E).
113
Forty-five, female Saanen cross dairy goat kids were enrolled at approx. 11 weeks of
114
age. Goats were sourced at 24 hours of age from two CAE-negative, commercial farms.
115
Vaccinations were given when goats were approximately 2 days (Covexin 10, MSD Animal
116
Health), 60 days (Covexin 10, MSD Animal Health) and 90 d (Leptoshield, Zeotis) old. They
117
were disbudded at 20.8 ± 3.1 days of age (mean ± SD). Prior to enrolment, goats had
118
unrestricted access to pasture and a run-in shed bedded with wood shavings. They were fed
119
ad libitum milk replacer mixed according to package directions (i.e., 200 g replacer per kg of
120
water; Anlamb, Fonterra Ltd., Auckland, New Zealand) via a 10-space kid feeder (Milk Bar,
6
121
Waipu, New Zealand) refreshed twice daily, and also had ad libitum access to straw and
122
water.
123
Twelve days prior to the start of the study (d-14 to d-3), goats were moved into the
124
research facility to allow for acclimation to housing and diet (described below). Goats were
125
categorized by weight, and then randomly allocated from each category to the pens, ensuring
126
there was a similar mean weight per pen (mean ± SE: 17.4 ± 1.4 kg; P > 0.1). The research
127
building had solid concrete floors and solid walls (drywall on one side, and slatted wood on
128
three sides). A raised metal platform was installed on top of the concrete (22.5 cm off the
129
floor) onto which the experimental pens were constructed using steel jailer gates (Gallagher
130
Group Ltd, Hamilton, New Zealand). Goats were moved into pens (n = 5 goats/pen)
131
measuring 2.65 m x 3 m (1.6 m2/goat). Pens had plywood floors covered with wood shavings
132
(approximately 10 mm particle size) at a depth of 15 cm. The pens had solid plywood sides
133
separating them from other pens, so individuals in a pen could not interact with neighboring
134
goats. Each pen contained a hay feeder (75 cm x 65 cm x 22 cm) and a meal feeder (77cm x
135
31 cm, 20 L, McKee Plastics Ltd, Hamilton, NZ) that were attached to the side of the pen at a
136
height of 128 cm and 42 cm above the floor, respectively. Lights were switched on at 0715 h
137
and off at 1730 h. Milk continued to be mixed according to package directions and was split
138
over two equal meals at 0800 h and 1630 h each day (approximately 0.9 kg/goat, which was
139
in excess of consumption); it continued to be provided in the same kid feeder. Goats had ad
140
libitum access to water, hay and straw. They also had ad libitum access to pellets (Dunstan
141
Fibre Grow, Dunstan Nutrition Ltd, Hamilton, New Zealand) which was replaced during
142
morning milk feeding and topped up if required in the afternoon.
143 144
Experimental design
7
145
Three weaning practices were compared: abrupt weaning from milk (AB), gradual
146
reduction in the concentration of milk replacer while keeping the milk volume constant
147
(DILU) and gradual reduction of the volume of milk provided (VOL). The reduction in the
148
concentration of milk replacer (DILU) treatment was based on the concentration of milk
149
replacer provided to goats in each DILU pen during the two baseline days (d-2 and d-1). The
150
reduction in volume of milk (VOL) treatment was based on the average volume of milk
151
consumed by goats in each VOL pen during the two baseline days (d-2 and d-1). For AB,
152
there was no change in milk allowance from d0 to d5. Milk replacer concentration (DILU) or
153
milk volume (VOL) were decreased, in a step-wise fashion (i.e., by 30%, every 2 days from
154
d0 to d5), with complete weaning from milk on d6 (Table 1). Treatments were randomly
155
assigned to the first three pens and then the order was replicated (Fig. 1) (n = 3
156
pens/treatment, 5 goats/pen).
157 158
Measures
159
Weight gain and feed intake
160
Goats were weighed by members of the research team that were blind to the
161
treatments on d-8, d-1, d3, d6, d9 and d12 (Table 2), and these weights were used to calculate
162
average daily gain (ADG; g/day/goat) between those time periods (baseline, early treatment,
163
late treatment, early no milk, late no milk). The volume of milk provided to each pen was
164
measured and weighed before and after each morning and afternoon feeding. Daily milk
165
intake was calculated for each pen as weight of milk fed minus weight of milk refused.
166
Similarly, each morning the remaining pellets from each pen were weighed before filling the
167
troughs with a known quantity of pellets, and daily pellet intake were calculated. Milk and
168
pellet refusals and intakes were divided by five to allow for reporting on a per goat basis.
169
8
170 171
Vocalizations Vocalizations could not be observed from the video footage as it was not possible to
172
know which pen the vocalizations were emanating from, therefore they were recorded via
173
live observations, beginning two days prior to the start of treatments and then throughout the
174
treatment period (Table 2). The frequency of vocalizations emanating from each pen was
175
recorded for 1 h prior to feeding (morning: 0700-0800 h, afternoon: 1500-1600 h) and 1 h
176
after feeding (morning: 0830-0930 h, afternoon: 1630-1730 h) with a 30-minutes pause for
177
feeding (0800-0830 h and 1600-1630 h). These observations were done on a pen basis as it
178
was not always possible to know which goat in each pen was vocalizing. Elevated platforms
179
were placed outside of the experimental pens to minimize disturbance to the goats and to
180
allow for a clear view of two pens at all times (Fig. 1). To further reduce the chance of goats
181
vocalizing because of human presence, observers sat quietly and motionless for 15 minutes
182
prior to beginning each observation. At each observation session, five observers watched two
183
pens each, resulting in one pen always being watched in duplicate. The duplicate observation
184
was used in a REML model with observer as a fixed effect, and observation session as a
185
random effect to confirm inter-observer reliability. Observers were blind to treatments and
186
rotated positions at the next observation session.
187 188
Rumination behavior
189
Behavior was recorded continuously in real time (30 frames/s) using overhead
190
cameras (DS-2CD2332-I, Hikvision, Hangzhou, China) attached to the ceiling of the facility.
191
The cameras’ built-in infrared light enabled night recordings to be carried out. Rumination
192
behavior was measured using Premiere Pro software (Adobe, USA). Two goats per pen were
193
pseudo-randomly selected (i.e., randomly selected, except that if the selected goat was brown
194
or black, which precluded reliable monitoring of chewing activity at night, it was excluded
9
195
and replaced by a randomly selected white goat). These focal goats were then continuously
196
observed for 24 h on d-1 (baseline) and d8 (at which time all treatments had been without
197
milk for 3 days) (Table 2). Rumination involves regurgitation, chewing and subsequent
198
swallowing of an individual bolus. Rumination times were taken from the start of each bolus
199
regurgitation until swallowing (Hooper and Welch, 1983; Schirmann et al., 2009). These
200
points were defined as follows: 1) Onset: Individual’s cheeks fill. If cheek fill is not visible
201
(i.e., because goat moves its head out of from camera view) then onset is coded beginning at
202
first jaw movement, or ears beginning to move up and down as a result of jaw movement.
203
Preference of onset signal is in the following order: cheek fill > first jaw movement > ear
204
movement. 2) End: Individual swallows bolus. If swallowing motion is not visible, then end
205
is coded from final jaw movement, or ears ceasing movement up and down as a result of jaw
206
movement ceasing. Preference of signal is in the following order: swallowing > final jaw
207
movement > ceasing ear movement. This definition was validated through a small sampling
208
of regurgitation times (two boli from five randomly selected goats), where the time delay
209
between these signals was determined for both onset and end of rumination. The total
210
difference never exceeded 1 s, which was the smallest unit of time used in this study. One
211
observer recorded all rumination behavior and was blind to treatment; intra-observer
212
reliability was calculated using total rumination time for two goats for 2 hours. We report the
213
number of regurgitated boli (number/day), the chewing time of each boli (seconds/boli), and
214
the inter-boli length (seconds between boli); calculations using these values provide
215
rumination bouts (number/day), rumination bout length (minutes/bout), boli regurgitated per
216
bout (number/bout) and total rumination time (hour/day). A rumination bout was defined as a
217
period of successive bolus regurgitations followed by a period of at least 60 seconds where
218
no regurgitations occurred. The length of each rumination bout was the sum of chewing and
219
the time between chewing within a single bout. Total rumination duration was taken as the
10
220
sum of the time of each rumination bout. Any rumination which was interrupted by the focal
221
individual moving out of sight was removed from calculations of the chewing time and the
222
inter-boli length (<1% of all regurgitations).
223 224
Lying behavior
225
Lying and standing behavior was recorded continuously using HOBO pendant G data
226
loggers (64k, Onset Computer Corporation, Bourne, MA, USA) set at 1-min intervals
227
recording the X and Z axes for the duration of the trial (Table 2). The loggers were fitted into
228
purpose made fabric pouches which were attached on the lateral side of the right hind leg
229
above the metatarsophalangeal joint. Accelerometers were placed vertically on the leg such
230
that the x-axis ran perpendicular to the ground, pointing in the dorsal direction and the z-axis
231
ran parallel to the ground, pointing toward the mid-plane of the goat. Accelerometers were
232
initialized and downloaded using Onset HOBOware Pro software (Onset Computer
233
Corporation, version 3.7.2). Raw g-forces were converted into binary values (e.g., lying = 0,
234
standing = 1) and daily summaries of lying time (h/d) and lying bout frequency (no. bouts/d)
235
were calculated in SAS 9.3 (SAS Institute Inc., Cary, NC, USA) using a code designed for
236
this purpose (AWP UBC, 2016) and validated for use in goats (Zobel et al., 2015). Lying
237
behavior was paired with rumination behavior, and therefore only the data collected by the
238
loggers on the focal goats was used in analysis (n = 3 treatments/pen with 2 focal goats per
239
pen).
240 241 242
Statistical analysis Data were analyzed by analysis of variance using GenStat statistical software
243
(Version 18, VSN International, UK). There were three randomized replicated pens, each
244
containing five goats, for each of the three weaning treatments (AB, DILU and VOL). All
11
245
pens were included in the analysis of each variable, with the exception of pen eight for
246
rumination, where a camera fault prevented accurate scoring of regurgitation, and pen nine
247
for milk consumption, where the nipples of the milk feeder were adjusted during the baseline
248
period. Since residual plot inspection showed that all data met the normality assumptions, no
249
transformations of the data were performed. A repeated measures Residual Maximum
250
Likelihood (REML) analysis (Patterson and Thompson, 1971) was run for each outcome
251
variable (ADG, change in milk refusal, change in pellet intake, vocalizations, rumination
252
behavior, and lying behavior), fitting weaning treatment, period and the interaction between
253
treatment and period as fixed effects, and pen, and goat within pen, as random effects. Mean
254
separation was assessed by Fisher’s protected Least Significant Difference (LSD). The period
255
effect in each model was based on when sampling occurred for each outcome variable. ADG
256
was compared during the following periods: baseline (d-8 to d-1), early treatment (d-1 to d3),
257
late treatment (d3 to d6), early no milk (d6 to d9) and late no milk (d9 to d12) for each
258
treatment. For change in milk refusals and pellet intake, the 2-day weaning step down periods
259
were compared (d0 to d1, d2 to d3, d4 to d5, d6 to d7 and d8 to d9) for each treatment. For
260
vocalizations there were two periods: milk feeding (d0 to d5) and no milk (d6 to d8), and for
261
rumination behavior and lying behavior, there were also two periods: baseline (d-1: one day
262
prior to the start of the weaning treatments) and 3 days after all treatments had not received
263
milk (d8) compared for each treatment. Each outcome variable was averaged according to
264
their respective period before testing in the model. Results are reported as mean ± SED,
265
unless otherwise stated.
266 267
Results
268
Behavioral observation reliability
12
269
No differences were found between observers for scoring vocalizations before and
270
after feeding throughout the entire study (P = 0.48). For rumination behavior, good intra-
271
observer reliability was achieved prior to the beginning of observations (weighted kappa, κw
272
= 0.89).
273 274
Average daily gain (ADG)
275
Prior to weaning (d-8 to d-1), ADG was similar among all treatments (0.3, 0.2, 0.2 ±
276
0.06 kg/d/goat for AB, DILU and VOL treatments, respectively; P = 0.641). During the first
277
3 days of the treatment period (d0 – d2), goats in the DILU pens had lower (P < 0.05) ADG
278
(0.1 ± 0.07 kg/d/goat) compared to AB (0.3 ± 0.07 kg/d/goat) and VOL (0.2 ± 0.07 kg/d/goat)
279
treatments (treatment effect: P = 0.01). During the subsequent periods, ADG did not differ (P
280
> 0.05) among treatments.
281 282 283
Milk and pellet intake There was no treatment effect on the change in milk refused by goats over the 6-day
284
weaning treatment period (milk refused [change from baseline]: -196, -274, -103 ± 116.6
285
g/d/goat for AB, DILU and VOL treatments, respectively; P = 0.430). However, there was an
286
effect of period (P < 0.001); during step 1 (d0 – d1), there were less refusals compared to the
287
other weaning steps (milk refused [change from baseline]: -98, -227, -249 ± 25.6 g/d/goat for
288
step 1, step 2 (d2 – d3) and step 3 (d4 – d5), respectively).
289
There was no effect of treatment on change in pellet intake (P = 0.617), however there
290
was an effect of weaning step (P < 0.001) and a step by treatment interaction (P = 0.003; Fig.
291
2). During steps 1 and 2 (d0 – d4) when milk was still being offered, there was no difference
292
among AB, DILU and VOL treatments in change in pellet intake (P = 0.11). However, during
293
step 3 (d4 – d5), DILU goats were eating twice as much pellets as AB and VOL goats (P <
13
294
0.05). During step 4 (d6 – d7) after milk was no longer offered, VOL goats consumed less
295
pellets than AB and DILU goats (P < 0.05). There was no difference (P > 0.1) in change in
296
pellet intake among treatments during step 5 (d8 – d9).
297 298
Behavior
299
There were no treatment differences for vocalizations before and after feeding (P =
300
0.8), nor was there a treatment by period interaction (P = 0.7). However, after milk was no
301
longer offered (d6 – d9), compared to when they had milk all treatments dramatically
302
increased their vocalizations in the observation session after feeding (P = 0.003); no
303
difference was seen in the observation session before pellet feeding (P = 0.25) (Fig. 3).
304
Abruptly weaned goats performed more rumination bouts on d8 (when milk was no
305
longer provided) compared to d-1, but the frequency of rumination bouts was similar on d-1
306
and d8 for DILU and VOL goats (treatment by period effect: P = 0.019; Fig. 4). Compared to
307
baseline, on d8 goats ruminated for longer, rumination bouts were longer, more boli were
308
regurgitated over the day as well as within individual bouts, the time spent chewing during
309
individual boli increased, and the time between regurgitated boli decreased (Table 3).
310
Weaning treatment had no effect (P > 0.1) on lying times and lying bout frequency,
311
nor was there a treatment by period interaction (P > 0.1). However, once milk was no longer
312
offered (d8), the proportion of time goats spent lying and ruminating concurrently increased
313
(Table 3; P < 0.001).
314 315 316
Discussion Weaning goats by diluting the concentration of milk replacer resulted in goats
317
consuming more pellets prior to complete milk removal compared to the other weaning
318
treatments evaluated. This increase in pellet consumption followed the initial lower ADG
14
319
recorded for this treatment, hence it is likely that these goats consumed more pellets to
320
compensate for the reduced energy intake provided by the diluted milk. A similar pattern was
321
noted in calves, where animals that received gradually less concentrated milk, consumed
322
more starter diet prior to milk removal compared to calves given access to non-diluted milk
323
(Jasper et al., 2008). Interestingly, goats gradually weaned by reducing the volume of milk
324
replacer did not appear to similarly compensate for the reduced energy intake by consuming
325
more pellets, which is contradictory to studies in dairy calves (reviewed in Khan et al., 2011).
326
Nonetheless, in the current study the impact of treatment was minimal, and at weaning all
327
treatments had similar weight gains, therefore none of the treatments appeared to be superior
328
to the others based on performance measures (e.g., intake and growth).
329
After complete milk removal, it took longer for goats receiving less milk (VOL) prior
330
to weaning to start consuming pelleted feed, compared to the other two treatments. It is
331
unclear why gradually reducing milk volume did not stimulate kids to consume more pelleted
332
feed, however ADG was not negatively impacted in these goats, suggesting that they were
333
still receiving adequate energy to maintain normal growth. Different weaning practices may
334
cause different sensations of hunger. In human trials, viscosity affected satiety; a thick liquid
335
meal left people feeling more full and satiated than a less viscous meal (Camps et al., 2016).
336
Therefore, goats that received the same concentration of milk replacer as they received prior
337
to the start of the weaning treatments, albeit at a reduced volume, may have felt fuller after
338
feeding due to its greater viscosity than those that received a diluted and less viscous meal.
339
Alternatively, goats receiving less milk could have satiated their remaining hunger by
340
increasing the consumption of hay and straw rather than pellets. In the present study, we were
341
unable to monitor the consumption of hay and straw; this was a limitation of the study design,
342
and thus we are unable to support this speculation.
15
343
Complete removal of milk resulted in kids vocalizing more after weaning and these
344
results are similar to other reports in kids (Magistrelli et al., 2013) and calves (Budzynska and
345
Weary, 2008; Jasper et al., 2008). However, in the present study weaning strategy did not
346
affect the frequency of vocalizations in response to complete milk removal. Magistrelli et al.
347
(2013) suggested that kids gradually given less milk prior to weaning only vocalized more
348
when the milk was completely removed from their diet; unfortunately, their results were only
349
descriptive. Calves that were gradually weaned by diluting the milk with water, vocalized as
350
much as abruptly weaned calves, when the milk was completely removed (Jasper et al.,
351
2008). Therefore, it is unsurprising that gradually reducing the volume or the concentration of
352
milk in the diet in the present study also did not prepare goats for complete milk removal. It
353
is worth noting that in the present study, while treatment groups did not have visual or tactile
354
contact with one another, they could hear one another; therefore, it is possible one treatment
355
vocalizing triggered the others to vocalize as well (Watts and Stookey, 2000).
356
Jasper et al. (2008) suggested that calves may vocalize more after weaning because
357
they are experiencing withdrawal as a result of no longer being able to suckle, rather than due
358
to the removal of milk from their diet per se; this is suggested because suckling involves the
359
opiate system. Replacing milk with warm water caused calves to vocalize less in response to
360
complete milk removal, but did not completely prevent the vocal response to weaning
361
(Budzynska and Weary, 2008; Jasper et al., 2008). Therefore, in future studies it would be
362
worth evaluating the mechanisms that are involved in the behavioral response to weaning
363
(e.g., hunger or suckling withdrawal), so that appropriate alternative weaning strategies can
364
be developed that satisfy the behavioral needs of goats. For example, replacing milk with
365
warm water would continue a goat’s ability to suckle, and perhaps help goats transition better
366
from a milk-based to a completely solid feed diet.
16
367
Adult goats spend 25-30% of their day ruminating (6.1 hours/day, Domingue et al.,
368
1991; 7.2 hours/day, Von Engelhardt et al., 2006; Jalali et al., 2012). In the present study,
369
removal of milk access resulted in a dramatic increase in time spent ruminating. Just 3 days
370
after milk removal, kids were ruminating at levels over 70% of what has previously been
371
reported for adult goats. Similarly to the current trial, 3 month old goat kids were previously
372
reported ruminating for 4.7 ± 0.5 hours/day (Hooper and Welch, 1983); interestingly, those
373
kids were less than half the body weight of the kids in the current study, suggesting age,
374
rather than body weight, plays a major role in the development of rumination. Treatment did
375
not impact the majority of the rumination behavior observed. Goats were enrolled in this
376
study at approximately 3 months of age; this is similar to the reported weaning age on New
377
Zealand dairy goat farms (Todd et al., in press). However, it has been reported that goat kids
378
may be weaned as young as 5 week of age (Lu and Potchoiba, 1988), and therefore we
379
suggest that age played a significant factor in the lack of treatment differences in the current
380
study. Even prior to weaning, kids were ruminating for over 3 hours/day. It is possible that if
381
the kids were younger, the treatment which promoted increased pellet intake (e.g., reduced
382
volume) would have had more of an impact on rumination. Indeed, in calves it has been
383
shown that rumination behavior is affected dramatically by age at weaning (e.g., a 4-fold
384
increase in rumination when calves were 8 week old vs. 6 week old; Eckert et al., 2015).
385
However, the aim of this study was to evaluate different weaning practices in 12-week-old
386
goat kids as this age is relevant to the New Zealand dairy goat industry.
387
It has been reported that rumination may occur during standing and walking (goats,
388
Paulo and Lopes, 2014; cows, Schirmann et al., 2009; bighorn sheep, Moquin et al., 2010).
389
We found that goats in the current trial spent very little time ruminating while upright (i.e.,
390
less than 1% of the day). Indeed, goats spent almost 20% of their lying time ruminating after
391
weaning. We suggest that this may be a function of the housing environment, which provided
17
392
sufficient space for the goats, but was not enriched in ways that might promote activity, and
393
therefore the goats spent up to 70% of their time lying down.
394
In conclusion, continued vocalization in the 3 day period after milk was no longer
395
provided suggests that the goats had not yet adjusted to the change in routine. However,
396
pellet intake and ADG were similar among the weaning treatments, suggesting that none of
397
the weaning strategies evaluated were better to the other when weaning 12-week-old goats
398
when considering performance measures. Therefore, if the goats are adjusted to consuming
399
hard feeds, any of these weaning strategies could be recommended to dairy goat farms when
400
weaning at this age.
401 402 403 404
Conflict of interest statement None of the authors has any financial or personal relationships that could inappropriately influence or bias the content of the paper.
405 406 407
Acknowledgements The authors gratefully acknowledge the assistance from AgResearch staff and
408
students (Tania Blackmore, Rebecca Yeates, Betina Bruce, Briar Roberston and Melissa
409
Hempstead). Funding was provided by the New Zealand Ministry of Business, Innovation
410
and Employment (C10X1307), as well as the Dairy Goat Co-operative (NZ) Ltd. We also
411
would like to thank NZ goat farmers for their input into this project.
412 413 414 415
Ethical statement All procedures involving animals were approved by the AgResearch Animal Ethics Committee (protocol no. 13685) under the New Zealand Animal Welfare Act 1999.
416 417 18
418
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programs on growth of Saanen kids. Anim. Sci. J. 78, 281–285.
476
Watts, J.M., Stookey, J.M., 2000. Vocal behaviour in cattle: The animal’s commentary on its
477
biological processes and welfare. Appl. Anim. Behav. Sci. 67, 15–33.
478
Zobel, G., Weary, D.M., Leslie, K., Chapinal, N., von Keyserlingk, M.A.G., 2015. Technical
479
note: Validation of data loggers for recording lying behavior in dairy goats. J. Dairy Sci. 98,
480
1082–1089.
481
21
482
Table 1. Description of weaning treatments illustrating the percentage of milk volume (AB and VOL treatments) or concentration of milk
483
replacer (VOL treatment) provided to goats in relation to the baseline pre-weaning treatment period. Milk replacer concentration (DILU) or milk
484
volume (VOL) were decreased in step-wise fashion every 2 days, leading up to complete weaning on day 6. -2
-1 Baseline
Treatment1 AB
100%
100%
DILU
100%
100%
VOL
100%
100%
0
1
Step 1 100% 100 % 70% 70 % 70% 70 %
Days relative to treatment 2 3 4 5 Treatment Step 2 Step 3 100% 100% 100% 100%
6 No milk 0%
50%
50%
20%
20%
0%
50%
50%
20%
20%
0%
485 486
1
487
but milk volume remained consistent) and VOL (volume of milk was reduced every 2 days from d0 to d5).
Treatments: AB (no change in milk allowance from d0 to d5), DILU (concentration of milk replacer was reduced every 2 days from d0 to d5,
22
488
Table 2. Timeline of measurements. The days that measures were recorded are shaded. Day relative to treatment -12 -11 -10 -9 -8 -7 -6 -5 -4 -3
Acclimation
-2
-1
Baseline
0
1
2
3
Treatment
4
5
6
7
8
9
10
11
12
No Milk
Weight Milk intake Pellet intake Vocalizations Rumination Lying
489 490 491
23
492
Table 3. Rumination behavior and the proportion of the day focal goats spent lying and
493
standing while ruminating or not (n = 3 pens/treatment, 2 goats monitored/pen). Daily
494
behaviors were measured during the baseline period (d-1: one day prior to the start of the
495
weaning treatments) and after all treatments had not received milk for 3 days (d8). Period1 Baseline
No milk offered
SED
P-value
(d-1)
(d8)
Time (hours(h)/day (d))
3.5
5.2
0.2
<0.001
Bouts (number (n)/d)
26.2
30.9
1.3
0.002
Bout length (minutes (min)/bout)
8.5
10.6
0.6
0.005
Boli regurgitated (n/d)
304
441
21.7
<0.001
Time spent chewing (seconds
31.5
33.7
0.5
<0.001
Inter-boli length (s between boli)
11.1
9.6
0.4
0.003
Boli regurgitated (n/bout)
11.9
14.9
0.9
0.007
Lying, while ruminating
10.8
17.9
1.0
< 0.001
Lying, while not ruminating
52.4
45.1
1.1
< 0.001
Standing, while ruminating
0.4
0.9
0.3
0.05
Standing, not ruminating
36.4
36.2
0.6
0.6
Rumination
(s)/boli)
Lying and standing behavior (%/d)
496
1
497
treatment and period were found, therefore only effect of period is reported.
With exception of rumination bouts, no treatment effect and no interaction between
498 499 24
500
List of figure captions
501
Figure 1. Pen layout. Treatment was randomly selected for the first three pens, and then
502
allocated to the remaining pens in replicated order. Trapezoids represent observer locations
503
for vocalization observations (observer location 2 and 3 monitored one of the same pens,
504
providing daily inter-observer reliability).
505 506
Figure 2. Mean (± SED) change in pellet intake (g/d/goat) from baseline during a 6-day
507
weaning period (d0 – d5) that consisted of three, 2-day step changes, and a 4-day period (d6 –
508
d9) where no treatments received milk (n = 3 pens/treatment, 5 goats/pen). Treatments: AB:
509
no change in milk allowance from d0 – d5; DILU: concentration of milk replacer reduced
510
every 2 days from d0 – d5, with constant volume of water; VOL: volume of milk reduced
511
every 2 days from d0 – d5. Milk was removed from all treatments on d6. *DILU differ from
512
AB and VOL treatments at P < 0.05. †VOL differ from AB and DILU treatments at P < 0.05.
513 514
Figure 3. Mean (± SED) number of vocalizations (no./pen/period) performed by goats (n = 3
515
pens/treatment, 5 goats/pen) over a 1 h period before and 1 h period after feeding, when milk
516
was still being provided (d0 – d5) and when milk was no longer offered (d6 – d8). No
517
treatment effect and no interaction between treatment and period were found, therefore only
518
effect of period is reported. *Means within observation period differ at P < 0.05.
519 520
Figure 4. Mean (± SED) rumination bouts (no./d/goat) before treatments began (d-1) and 3
521
days after milk was no longer offered (d8) (n = 3 pens/treatment, 2 goats monitored/pen).
522
Treatments: AB: no change in milk allowance from d0 – d5; DILU: concentration of milk
523
replacer reduced every 2 days from d0 – d5, with constant volume of water; VOL: volume of
25
524
milk reduced every 2 days from d0 – d5. Milk was removed from all treatments on d6.
525
*Means within treatment differ at P < 0.05.
526
26
527
Figure 1.
528 529
27
Figure 2. Change in pellet intake from baseline (g/d/goat)
530 531
Milk
600
No milk †
500
* 400 300 200 100 0 0-1 -100
2-3
4-5
6-7
8-9
Days relative to start of weaning treatments AB
DILU
VOL
532 533 534
28
535
Figure 3. Milk
No milk
Vocalizations (no./pen/period)
140
*
120 100 80 60 40 20 0 Before Feeding -20
After Feeding
Observation period
536 537 538
29
539
Figure 4. Milk
Rumination bouts (no./d/goat)
40
No milk
*
35 30 25 20 15 10 5 0 AB
DILU
VOL
Weaning treatment
540 541 542
30
Highlights •
Gradual reduction in milk concentration caused goats to initially gain less weight
•
Gradual reduction in milk volume caused goats to consume less pellets initially
•
After milk removal, all weaning treatments vocalized more after pellet feeding
•
None of the weaning strategies evaluated were superior than the others