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Intermittent suckling affects feeder visiting behaviour in litters with low feed intake
Livestock Science 127 (2010) 137–143
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Intermittent suckling affects feeder visiting behaviour in litters with low feed intake Wikke I. Kuller a,⁎, Nicoline M. Soede b, J. Elizabeth Bolhuis b, Hetty M.G. van Beers-Schreurs a,1, Bas Kemp b, Jos H.M. Verheijden a, Marcel A.M. Taverne a a b
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht Institute of Animal Sciences, Marburglaan 2, 3584 CM Utrecht, The Netherlands Adaptation Physiology Group, Department of Animal Science, Wageningen University, Marijkeweg 40, 6700 AH Wageningen, The Netherlands
a r t i c l e
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Article history: Received 20 February 2009 Received in revised form 25 August 2009 Accepted 28 August 2009 Keywords: Pig Creep feed Intermittent suckling Nursing Weaning Behaviour
a b s t r a c t Intermittent suckling (IS) has proven to stimulate creep feed intake in suckling piglets. This paper describes the development of feeding behaviour in three litters with high (H) and three litters with low (L) feed intake during lactation in both control (C) and IS treatment. In order to synchronize the start of intermittent suckling within a farrowing room, treatment day 0 (T0) was designated as the start of data collection. IS litters were separated from the sow for a period of 12 h/day (0930 to 2130) from T14 to weaning (T25). Feeder visits of individual piglets and nursing behaviour were analysed from continuous video recordings at 5 treatment days: T13, T16, T24, T25 and T26. A high number of CL piglets never visited the feeder during lactation; at T24, 56% of the CL piglets did not visit the feeder. On the other hand, 91% of the ISL and CH piglets and all ISH piglets visited the feeder at least once at T24. In contrast to the other groups, no increase was seen in visiting frequency during lactation in CL piglets. At T24, visiting frequency was higher in ISL than in CL piglets. So, IS stimulated piglets from low feed intake litters to visit the feeder. Between T16 and T24, total feeder time increased in piglets from all groups (P < 0.05), except in CL piglets in which no change was found (P > 0.10). Latency to first visit to the feeder after weaning did not differ between groups. It is concluded that IS stimulates piglets from litters with a low level of creep feed intake to visit the feeder during lactation, which familiarizes them with the feeder and the feed during lactation. The IS treatment does not affect feeder visiting behaviour of piglets with an anyhow high level of feed intake during lactation. © 2009 Elsevier B.V. All rights reserved.
1. Introduction In pigs, creep feed intake during lactation is positively correlated with feed intake after weaning (Bruininx et al., 2002) and with average daily gain after weaning (Appleby et al., 1991; Bruininx et al., 2002; Pajor et al., 1991). Also net absorption in the small intestine (i.e. the net result of secretion and absorption) immediately after weaning is significantly higher in piglets consuming creep feed during lactation than in non-eating piglets (Kuller et al., 2004b), ⁎ Corresponding author. Tel.: +31 30 2532028; fax: +31 30 252 1887. 1 Present address: The Animal Health Service, Pig Health Department, Arnsbergstraat 7, Postbus 9, 7400 AA Deventer, The Netherlands.
1871-1413/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2009.08.009
thereby probably decreasing the risk of post-weaning diarrhoea. Hence, stimulating creep feed intake in suckling piglets could be important to optimize pig performance after weaning. Creep feed intake in suckling piglets is usually low during lactation but can be stimulated by intermittent suckling (IS; Berkeveld et al., 2007; Kuller et al., 2004a; Kuller et al., 2007), a management procedure in which piglets are separated from the sow for a number of hours every day during the second half of lactation. IS increases average creep feed intake per piglet and also increases the number of litters with a high feed intake during lactation (Kuller et al., 2004a). However, also during IS treatments, litters have been identified with little or no creep feed intake during lactation. Apparently, some litters
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start eating creep feed during lactation, whereas others hardly increase their feed intake when subjected to IS. In a previous experiment (Kuller et al., 2004a), we found that IS litters consuming little or no creep feed during lactation still tended to have higher feed intake and weight gain shortly after weaning than control litters with a comparable low feed intake during lactation. So, positive effects of IS on post-weaning performance may also be mediated by other factors than by increased creep feed intake during lactation alone. Little is known regarding the development of creep feed intake during lactation by individual piglets, because creep feed intake is usually determined at the litter level. One way to investigate the development of creep feed intake by individual piglets during lactation and shortly after weaning is to investigate feeder visiting behaviour by quantifying the number and duration of visits to the feeder over time. It is of interest to study the development of feeder visiting behaviour in intermittently suckled piglets, not only because IS stimulates creep feed intake during lactation but especially because it also stimulates feed intake shortly after weaning in litters with a low level of creep feed intake during lactation. We hypothesise that IS will stimulate especially piglets from low feed intake litters to visit the feeder during lactation, thereby familiarizing piglets with the feed and the feeder during lactation. In order to find out whether milk intake could have influenced creep feed intake, nursing characteristics were also studied. 2. Materials and methods 2.1. Treatments, animals and housing The experimental design was approved by the Ethical Committee of the Veterinary Faculty of Utrecht University (The Netherlands). The sows used in the current experiment were also part of another study investigating the effects of intermittent suckling on weight gain and feed intake until slaughter (Kuller et al., 2007). Sows were allotted to either a control (C) or intermittent suckling (IS) treatment. Control piglets had access to the sow for 24 h/day until weaning. IS piglets were separated from the sow for 12 h each day (0930 until 2130) and allowed access to the sow for the other 12 h (2130 until 0930). Only one treatment was applied per farrowing room to avoid an influence by suckling of control piglets on IS piglets, since suckling is highly synchronized between animals in a room. In order to synchronize the start of intermittent suckling within a farrowing room, treatment day 0 (T0) was designated as the start of data collection. Piglets were born from 1 day before to 2 day after T0. Intermittent suckling always started at T14 and piglets were weaned at T25 at 0800 a.m. During the separation period, piglets and sow remained in the pen and were separated by a removable wooden partition (height 65 cm) that was attached on both sides to the farrowing crate of the sow, not allowing any physical contact between sow and piglets. The sows were housed in farrowing crates in a farrowing pen (2.40 × 1.80 m). The farrowing pen consisted of a partly solid floor and a partly slatted floor. During the separation period, IS piglets were allowed extra space (solid floor) at the back of the pen to create comparable floor space with that of the control piglets. Lights were on between 0730
and 2330. To facilitate video recordings, a low level of light (12 lux) was maintained during the night. At weaning sows were moved to a mating room and the piglets remained in the pen. Video recordings were made of 28 sows (14 IS and 14 control). From each treatment, six sows were selected, based on feed intake level of the litter during the complete lactation period; high (H): feed intake >90 g/piglet or low (L): feed intake <85 g/piglet). So, there were 3 CH litters (n = 32 piglets; control, high feed intake level) and 3 CL litters (n = 27 piglets; control, low feed intake level), 3 ISH litters (n = 28 piglets; intermittent suckling, high feed intake level) and 3 ISL litters (n = 32 piglets; intermittent suckling, low feed intake level). Before start of IS treatment no differences were found in feed intake of the litters (CH: 24± 11 vs. CL: 18± 2 vs. ISH 23 ± 3 vs. ISL: 15± 5 g/piglet; P > 0.10) and weights (CH: 4587 ± 523 vs. CL: 5075 ± 302 vs. ISH 5500± 354 vs. ISL:4550 ± 325 g/piglet; P > 0.10) between the groups. Data of individual litters are shown in Table 1. 2.2. Piglet feeding Water was available ad libitum by means of a drinking nipple at the rear end of the pen. Creep feed residuals were weighed per litter at 7 day intervals. Because no food wastage was observed (feeder was placed on a solid floor), disappeared feed was considered eaten. Creep feed based on milk products (34%), soybeans, corn, sugar, vegetable oil and a premix (12.8 MJ NE kg− 1, 21.7% CP, 14.7% crude fat, 2.0% crude fiber, 5.2% ash, 1.46% lysine, 0.86% calcium, 0.58% phosphorus, 160 mg kg− 1 copper, 500 units kg− 1 phytase; as-fed basis) was offered to the piglets ad libitum from T7 onwards and given in a round piglet trough (diameter 25 cm). From T14 onwards a pig feeder with 4 feeding spaces was used (11 cm feeder space/piglet). From T21 to T23 a gradual change (respectively 40%, 60% and 100% replacement) was made to a weaner diet, based on milk products (18.5%), barley, soy beans, corn, sugar, vegetable oil and a premix (11.4 MJ NE kg− 1, 17.9% CP, 10.7% crude fat, 2.9% crude fiber, 5.8% ash, 1.25% lysine, 0.77% calcium, 0.59% phosphorus, 160 mg kg− 1 copper, 500 units kg− 1 phytase; as-fed basis). This was given until T31 (7 days after weaning) of the experiment. 2.3. Measurements Video recordings were made continuously for 24 h at five treatment days; T13 (day before start of IS), T16 (3 days after onset IS), T24 (day before weaning), T25 (day of weaning) and T26 (day after weaning). All piglets had been marked on their back to allow individual identification. When a piglet stayed for at least 2 s with its head in the feeder, this was recorded as a visit and beginning and end of the visit were recorded. The following parameters of feeder visiting behaviour were calculated for each piglet: total time spent at the feeder per piglet per day (total feeder time, s), visiting frequency per day and average time per visit per day (average feeder time, s). Nursing was defined as more than 50% of the litter being active (massaging or sucking) at the udder. The nursing was considered to be ended by the sow, when she turned to sternal recumbence or, in case of a nursing while standing,
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Table 1 Littersize (n), weight and feed intake level of the individual litters in high and low eating litters in the control (C) and intermittent suckling treatment (IS), means ± SE. Trt
Sow
Parity
Level
n
C C C C C C IS IS IS IS IS IS
1 2 3 4 5 6 7 8 9 10 11 12
2 2 2 8 6 2 2 6 6 8 2 2
High High High Low Low Low High High High Low Low Low
10 12 10 11 8 8 9 7 12 10 12 10
Feed intake (g/piglet)
Piglet weight (g/piglet)
T7 to T13
T14 to T24
T25 to T32 (after weaning)
Birth
Start IS
Weaning
64 42 25 16 21 17 28 23 19 10 24 10
171 471 186 10 64 67 451 219 170 41 4 14
1857 2833 1380 727 1250 888 2429 1571 1500 1643 583 750
1550 ± 40 1458 ± 21 1389 ± 24 1198 ± 20 1585 ± 32 1513 ± 40 1609 ± 46 1551 ± 36 1145 ± 20 1509 ± 27 1281 ± 32 1500 ± 36
5571 ± 169 4366 ± 124 3798 ± 176 4504 ± 89 5191 ± 146 5531 ± 137 5949 ± 174 5751 ± 211 4801 ± 131 4657 ± 98 3941 ± 93 5052 ± 138
8377 ± 243 6465 ± 196 6700 ± 84 7479 ± 116 7367 ± 239 8296 ± 217 8531 ± 187 7037 ± 298 6634 ± 151 6819 ± 124 5439 ± 110 7000 ± 187
In the intermittent suckling treatment, piglets were separated from the sow from for 12 h/day (0930 to 2130) starting 11 days before weaning (T14). Piglets were weaned at 0800 h at T25.
she started moving forwards and backwards in her farrowing crate or laying down. The nursing was considered to be ended by the piglets when, after a nursing less than 50% of the litter was active at the udder. Nursing characteristics of the litter were: total time spent nursing per day, nursing frequency and average duration of each nursing.
effects of sow (nested within treatment and feed intake level) with compound symmetry covariance structure. The model included the effects of feed intake level, treatment and day of treatment and their interactions. Bonferroni corrections were applied to correct for multiple comparisons. Data are presented as (untransformed) means ± SE.
2.4. Statistical analysis 3. Results All statistical analyses were performed using the SAS 8.2 statistical software program (SAS Institute, Inc., Cary, NC). Skewed distributions of behavioural data on feeder visits (total feeder time, average feeder time and visiting frequency) were square root transformed. Data on creep feeder visiting behaviour were analysed using a linear mixed model (West et al., 2006), allowing for repeated measurements per subject (piglet, nested within sow and treatment and feed intake level) and random effects of sow (nested within treatment and feed intake level) and piglet (nested within sow and treatment and feed intake level) with unstructured covariance structure. The model included effects of feed intake level (H vs. L), treatment (IS vs. control) and day of treatment (T13, T16, T24, T25, T26) and their interactions. Effects of gender, weight at birth or at start of treatment, and weight gain between T0 and T6 or between T7 and T13 were not significant and therefore omitted from the model. Effects of sow and feeding level were tested against the effect of sow within treatment and feeding level, so litter was the experimental unit. Time to first visit to the feeder after weaning was analysed using the survival analysis package version 2.32 of R (2006). The model included treatment and feed intake level and their interaction and litter nested within treatment and feed intake level as a random effect. Nursing characteristics were analysed using a linear mixed model (West et al., 2006) allowing for repeated measurements per subject (sow, nested within treatment and feed intake level) and random effects of sow (nested within treatment and feed intake level). Data on litter activity were analysed using a linear mixed model allowing for repeated measurements per subject (sow, nested within treatment and feed intake level) and random
3.1. Performance No difference in feed intake was found between the treatments (C: 1489 ± 314 vs. IS: 1413 ± 274 g/piglet; P = 0.75) during the first seven days after weaning (See also Table 1). However, feed intake during this week was significantly higher in litters with high creep feed intake during lactation (1928 ± 237 g/piglet) than in litters with a low creep feed intake (974 ± 163 g/piglet; P = 0.02) and the interaction of treatment × feed intake level was not significant. Weight gain during treatment was higher in control litters (C: 238 ± 6.vs IS: 172 ± 3 g/piglet/day; P = 0.03), but no difference was found between litters with different creep feed intake during lactation (H: 207 ± 5 vs. L: 202 ± 6 g/piglet/day; P = 0.86) and no interaction of treatment × feed intake level was found. After weaning, however, weight gain was lower in CL litters than in the other litters (CL:77±7 vs. CH:208±7 vs. ISL:140±6 vs. ISH: 167±8 g/piglet/day; P=0.043). 3.2. Feeder visiting behaviour 3.2.1. Lactation period (T13 to T24) A high number of CL piglets never visited the feeder during lactation; at T24, 56% of the CL piglets did not visit the feeder (Table 2). On the other hand, at T24 91% of the ISL and CH piglets and all ISH piglets visited the feeder at least once. Visiting frequency (Fig. 1) increased between T13 and T16 in ISH piglets (P = 0.0001) and between T16 and T24 in CH (P = 0.0001) and ISL piglets (P = 0.0090), but did not increase in CL piglets (P = 0.1719). At T24, visiting frequency was higher in ISL than in CL piglets.
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Table 2 Percentage of piglets with either 0, 1 to 15, 16 to 30 or more than 31 visits per 24 h to the feeder in high and low eating control and intermittent suckling piglets (IS) litters. Day
Control
IS
High (n = 32) Number of visits
T13 T16 T24 T25 T26
Low (n = 27) Number of visits
High (n = 28) Number of visits
Low (n = 32) Number of visits
0
1–15
16–30
>31
0
1–15
16–30
>31
0
1–15
16–30
>31
0
1–15
16–30
> 31
0 22 9 0 0
75 63 59 9 0
25 16 16 41 41
0 0 16 50 59
30 56 56 0 0
56 44 44 67 37
15 0 0 33 22
0 0 0 0 41
32 7 0 0 0
54 43 32 7 0
14 21 50 39 61
0 29 18 54 39
19 44 9 0 0
75 56 78 63 19
6 0 9 25 34
0 0 3 13 47
In the IS treatment, piglets were separated from the sow for 12 h/day (0930 to 2130) starting 11 days before weaning (T14). Piglets were weaned at 0800 h at T25.
An increase in average feeder time (Fig. 1) was found between T16 and T24 in IS piglets (P < 0.05), but not in control piglets. Between T16 and T24, total feeder time increased in piglets from all groups (P < 0.05), except in CL piglets in which no change was found (P > 0.10). At T16 and at T24, total feeder time was higher in H piglets than in L piglets. 3.2.2. After weaning (T25 and T26) No differences were found between the treatments or between the feed intake levels in latency to first visit to the feeder after weaning (Fig. 2; Mean: ISH: 1.8 ± 0.2; CH: 2.3 ± 0.3; ISL: 5.8 ± 1.0; CL: 4.1± 0.7 h). Low feed intake piglets went for the first time after weaning to the feeder as litter (ovals in Fig. 2), in high feed intake litters this effect could not be discriminated. All piglets had visited the feeder at T25 and T26 (Table 2). Also the percentage of piglets visiting the feeder with a high frequency (>31 visits per day) increased after weaning, although it took until T26 before this high frequency of visits was seen in CL litters. Visiting frequency was higher in H than in L piglets at T25 (Fig. 1), but did not differ between treatments at T26. Total feeder time (Fig. 1) increased over time for all groups (P < 0.05). At T26, CL piglets had a lower total feeder time than piglets from the other treatments (P = 0.0001). 3.3. Nursing characteristics Once IS treatment had started, nursing frequency (Table 3) was lower in IS litters than in control litters. Within treatments, no differences were found in nursing frequencies for litters with high and low feeding level. Although average nursing time was often shorter in H than in L litters, this only resulted in a difference in total nursing time between H and L litters in the control group at T16 and T24 and not in the IS group. 4. Discussion It is known that IS increases feed intake before and after weaning (Kuller et al., 2004a; Berkeveld et al., 2007). In these studies some 60% of the IS litters, against 20% of the control litters, had an average feed intake per piglet of more than 600 g before weaning. So, the number of litters with high feed intake during lactation increased and the number of litters with low creep feed intake decreased by IS. Some litters could
not be stimulated by IS to consume a considerable amount of creep feed (Kuller et al., 2007). The current experiment showed, however, that IS also has a positive effect on litters with low feed intake during lactation. One day before weaning, piglets from low feed intake litters in the IS treatment had a higher visiting frequency than piglets from low feed intake litters in the control treatment. Further, visiting frequency and total feeder time increased in ISL piglets between T16 and T24, while in CL piglets no increase was seen during lactation. Also on the second day after weaning, total feeder time was higher in ISL than in CL piglets. It has been reported that piglets, placed in an unfamiliar environment and offered an unfamiliar source of feed after weaning, do not consume enough feed to meet energy requirements (Bark et al., 1986). Also other authors (Pluske and Williams, 1996) suggested that low feed intake levels by newly weaned piglets may be related to unfamiliar feeders. Pre-exposure to the smell or presence of novel food can reduce neophobia to the food (Nicol and Pope, 1994), which probably facilitates feed intake and thus weight gain after weaning. The difference in feeder visiting behaviour between ISL and CL litters in the our experiment might explain why in a previous study (Kuller et al., 2004a) we found that IS litters with a low creep feed intake during lactation had a higher feed intake and a higher average daily gain after weaning than control litters with a comparable feed intake during lactation. Although feed intake was very low in all L litters, including the ones exposed to the IS treatment, the feeder visiting behaviours and sampling of small amounts of feed may have prepared the piglet both behaviourally and physiologically, for the post-weaning situation (Brooks and Tsourgiannis, 2003; Petersen, 1994). The IS treatment did not affect feeder visiting behaviour of piglets with a high level of feed intake during lactation. Piglets in litters with a high feed intake had similar eating behaviour in the IS treatment and the control treatment, and this behaviour differed from L piglets both during and after lactation in a way that both visiting frequency and total feeder time were higher in H litters. Visiting frequency increased during lactation in H litters, which is in agreement with others (Delumeau and Meunier-Salaun, 1995; Wattanakul et al., 2005) who found that the number of creep feeding acts increased over time in the 3rd and 4th week of lactation. Like in previous studies, total feeder time increased by the end of lactation (de Passillé et al., 1989; Mason et al., 2003) and after weaning (Algers et al., 1990; Dybkjaer et al., 2006; Mason et al., 2003;
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Fig. 1. Visiting frequency, average feeder time and total feeder time in high (solid line, closed symbols) and low (dotted line, open symbols) eating litters in the control (circles) and intermittent suckling (triangles) treatment at different treatment days (24 h). In the control treatment piglets were continuously with the sow. In the intermittent suckling treatment, piglets were separated from the sow from for 12 h/day (0930 to 2130) starting 11 days (T 14) before weaning. Piglets were weaned at 0800 h at T25. Data are presented as means ± SE. Within a treatment day, different letters indicate significant differences between groups.
Morgan et al., 2001) in H piglets. It is known that piglets that start eating during one day will continue to do so on the next day (Appleby et al., 1991; Pajor et al., 1991), implying that piglets in high eating litters will probably not stop visiting the feeder and will continue eating after weaning. Therefore, it is less likely that they will encounter problems that are associated with low feed intakes after weaning, like a growth check or diarrhoea. After weaning, latency to first visit to the feeder did not differ between the groups in our experiment. Bruininx et al.
(2002) found that the number of piglets that did not eat after weaning declined faster in piglets with known creep feed intake before weaning than in non-eaters. However, he also found that the number of visits to the feeder after weaning did not differ between so called ‘eaters’ and ‘non-eaters’, but that the number of visits during which feed was consumed was higher in eaters. Therefore, it was suggested that piglets that are familiar with food at the moment of weaning (eaters) are more efficient in their food intake than piglets that are unfamiliar with the food (non-eaters). Thus, latency to first
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Fig. 2. Percentage of piglets that had not visited the feeder after weaning as a function of post-weaning interval. Ovals indicate piglets of the same litter. In the control treatment piglets were continuously with the sow. In the intermittent suckling treatment, piglets were separated from the sow from for 12 h/day (0930 to 2130) starting 11 days before weaning (T14). The experiment started at treatment day 0 (T0). Piglets were weaned at 0800 h at T25. Lights were turned off, at 15 h after weaning.
Table 3 Nursing characteristics of high and low eating litters in the control and intermittent suckling (IS) treatment. Nursing
Day2
Control1
IS1
High Mean Frequency
Average time (min)
Total time (min/day)
1
T13 T16 T24 T13 T16 T24 T13 T16 T24
28 30a 26a 5.4a,x 4.4a,x 3.5a,y 153x 129a,x 90a,y
Low SE 2 1 1 0.5 0.2 0.3 9 5 3.6
Mean 27 25a 27a 6.7a 6.5b 5.2b 181x 163b,x 144b,y
High SE 2 1 3 0.1 0.2 0.4 17 6 26
Mean x
32 19b,y 19b,y 4.9b,x 4.8a,x 5.5b,y 155x 89c,y 103a,y
Low SE 1 2 0 0.3 0.4 1 4 11 17
Mean x
30 20b,y 20b,y 5.3a 5.7b 5.8b 156x 113 ac,y 114a,y
SE 0 1 2 0.3 0.5 0.6 8 12 7
In the control treatment, piglets were continuously with the sow. Piglets in the IS treatment were separated from the sow for 12 h/day (0930 to 2130) beginning at treatment day 14 (T14). 2 T13 = day before start of IS; T16 = 3rd day of IS; T24 = day before weaning. a,b Within a row, means with a different superscript differ (P < 0.05). x,y Within a column, means with a different superscript differ (P < 0.05).
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visit to the feeder may not be a good parameter to distinguish eaters from non-eaters. Remarkably, low feed intake piglets went for the first time to the feeder after weaning as a litter. This could be the result of the synchronization of behaviour and nursings during lactation. Suckling behaviour is highly synchronized around nursings, which is mainly controlled by the sow's milk let down (Fraser, 1980). The synchronization of suckling leads to a concomitant synchronization of activity and inactivity and also programs litters to feed as a group (Brooks and Burke, 1998). This likely continues shortly after weaning. In addition, also feeding-related behaviours are often highly synchronized and socially facilitated in pigs (Hsia and Wood-Gush, 1982; Hsia and Wood-Gush, 1984). Feeder visiting behaviour was highly variable between piglets and litters and this has been related to differences in milk production by the sow (Delumeau and Meunier-Salaun, 1995). In our experiment, a difference in milk availability was imposed by denying access to the udder for 12 h/ day in the IS treatment. IS litters could only partly compensate these 12 h of separation by increasing suckling frequency or average nursing time in the hours that they had access to the sow. Although the effect of separation of piglets and sow on milk production is unknown, it is likely that milk intake of the piglets is decreased since IS piglets are lighter at weaning than continuous suckled piglets (Kuller et al., 2004a; Kuller et al., 2007). This decreased milk intake might have motivated the piglets to increase solid food intake as stated by others (Puppe and Tuchscherer, 2000). 5. Conclusion IS stimulated piglets from litters with a low level of creep feed intake to visit the feeder during lactation, which familiarized them with the feeder and the feed during lactation. The IS treatment did not affect feeder visiting behaviour of piglets with an anyhow high level of feed intake during lactation. References Algers, B., Jensen, P., Steinwall, L., 1990. Behaviour and weight changes at weaning and regrouping of pigs in relation to teat quality. Applied Animal Behaviour Science 26, 143–155. Appleby, M.C., Pajor, E.A., Fraser, D., 1991. Effects of management options on creep feeding by piglets. Animal Production 53, 361–366. Bark, L.J., Crenshaw, T.D., Leibbrandt, V.D., 1986. The effect of meal intervals and weaning in feed intake of early weaned pigs. Journal of Animal Science 62, 1233–1239. Berkeveld, M., Langendijk, P., Bolhuis, J.E., Koets, A.P., Verheijden, J.H.M., Taverne, M.A.M., 2007. Postweaning growth check in pigs is markedly
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reduced by intermittent suckling and extended lactation. Journal of Animal Science 85, 258–266. Brooks, P.H., Burke, J., 1998. Behaviour of sows and piglets during lactation. In: Verstegen, M.W., Moughan, P.J., Schrama, J.W. (Eds.), The lactating sow. Wageningen Press, Wageningen, pp. 301–331. Brooks, P.H., Tsourgiannis, C.H., 2003. Factors affecting voluntary feed intake of the weaned pig. In: Pluske, J.R., Le Dividich, J., Verstegen, M.W. (Eds.), Weaning the pig, concepts and consequences. Wageningen Academic Publishers, Wageningen, pp. 81–116. Bruininx, E.M.A., et al., 2002. Effect of feed consumption on individual feed intake characteristics and performance of group-housed weanling pigs. Journal of Animal Science 80, 1413–1418. de Passillé, A.M.B., Pelletier, G., Ménard, J., Morisset, 1989. Relationships of weight gain and behavior to digestive organ weight and enzyme activities in piglets. Journal of Animal Science 67, 2921–2929. Delumeau, O., Meunier-Salaun, M.C., 1995. Effect of early trough familiarity on the creep feeding behaviour in suckling piglets and after weaning. Behavioural Processes 34, 185–195. Dybkjaer, L., Jacobsen, A.P., Togersen, F.A., Poulsen, H.D., 2006. Eating and drinking activity of newly weaned piglets: effects of individual characteristics, social mixing, and addition of extra zinc to the feed. Journal of Animal Science 84, 702–711. Fraser, D., 1980. A review of the behavioural mechanism of milk ejection of the domestic pig. Applied Animal Ethology 6, 247–255. Hsia, L.C., Wood-Gush, D.G.M., 1982. The relationship between social facilitation and feeding behaviour in pigs. Applied Animal Ethology 8, 410. Hsia, L.C., Wood-Gush, D.G.M., 1984. Social facilitation in the feeding behaviour of pigs and the effect of rank. Applied Animal Ethology 11, 265–270. Kuller, W.I., et al., 2004a. Intermittent suckling: effects on piglet and sow performance before and after weaning. Journal of Animal Science 82, 405–413. Kuller, W.I., et al., 2004b. Intermittent suckling: effect of feed intake before weaning on net absorption in the small intestine. International Pig Veterinary Society, Hamburg, p. 726. Kuller, W.I., et al., 2007. Effects of intermittent suckling and creep feed intake on pig performance from birth to slaughter. Journal of Animal Science 85, 1295–1301. Mason, S.P., Jarvis, S., Lawrence, A.B., 2003. Individual differences in responses of piglets to weaning at different ages. Applied Animal Behaviour Science 80, 117–132. Morgan, C.A., Lawrence, A.B., Chirnside, J., Deans, L.A., 2001. Can information about solid food be transmitted from one piglet to another? Animal Science 73, 471–478. Nicol, C.J., Pope, S.J., 1994. Social learning in sibling pigs. Applied Animal Behaviour Science 40, 31–43. Pajor, E.A., Fraser, D., Kramer, D.L., 1991. Consumption of solid food by suckling piglets: individual variation and relation to weight gain. Applied Animal Behaviour Science 32, 139–155. Petersen, V., 1994. The development of feeding and investigatory behaviour in free-ranging domestic pigs during their first 18 weeks of life. Applied Animal Behaviour Science 42, 87–98. Pluske, J.R., Williams, I.H., 1996. The influence of feeder type and the method of group allocation at weaning on voluntary food intake and growth in piglets. Animal Science 62, 115–120. Puppe, B., Tuchscherer, A., 2000. The development of suckling frequency in pigs from birth to weaning of their piglets: a sociobiological approach. Animal Science 71, 273–279. Wattanakul, W., Bulman, C.A., Edge, H.L., Edwards, S.A., 2005. The effect of creep feed presentation method on feeding behaviour, intake and performance of suckling piglets. Applied Animal Behaviour Science 92, 27–36. West, B.T., Welch, K.B., Galecky, A.T., 2006. Linear Mixed Models. Chapman Hall/ CRC press.
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Intermittent suckling affects feeder visiting behaviour in litters with low feed intake Wikke I. Kuller a,⁎, Nicoline M. Soede b, J. Elizabeth Bolhuis b, Hetty M.G. van Beers-Schreurs a,1, Bas Kemp b, Jos H.M. Verheijden a, Marcel A.M. Taverne a a b
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht Institute of Animal Sciences, Marburglaan 2, 3584 CM Utrecht, The Netherlands Adaptation Physiology Group, Department of Animal Science, Wageningen University, Marijkeweg 40, 6700 AH Wageningen, The Netherlands
a r t i c l e
i n f o
Article history: Received 20 February 2009 Received in revised form 25 August 2009 Accepted 28 August 2009 Keywords: Pig Creep feed Intermittent suckling Nursing Weaning Behaviour
a b s t r a c t Intermittent suckling (IS) has proven to stimulate creep feed intake in suckling piglets. This paper describes the development of feeding behaviour in three litters with high (H) and three litters with low (L) feed intake during lactation in both control (C) and IS treatment. In order to synchronize the start of intermittent suckling within a farrowing room, treatment day 0 (T0) was designated as the start of data collection. IS litters were separated from the sow for a period of 12 h/day (0930 to 2130) from T14 to weaning (T25). Feeder visits of individual piglets and nursing behaviour were analysed from continuous video recordings at 5 treatment days: T13, T16, T24, T25 and T26. A high number of CL piglets never visited the feeder during lactation; at T24, 56% of the CL piglets did not visit the feeder. On the other hand, 91% of the ISL and CH piglets and all ISH piglets visited the feeder at least once at T24. In contrast to the other groups, no increase was seen in visiting frequency during lactation in CL piglets. At T24, visiting frequency was higher in ISL than in CL piglets. So, IS stimulated piglets from low feed intake litters to visit the feeder. Between T16 and T24, total feeder time increased in piglets from all groups (P < 0.05), except in CL piglets in which no change was found (P > 0.10). Latency to first visit to the feeder after weaning did not differ between groups. It is concluded that IS stimulates piglets from litters with a low level of creep feed intake to visit the feeder during lactation, which familiarizes them with the feeder and the feed during lactation. The IS treatment does not affect feeder visiting behaviour of piglets with an anyhow high level of feed intake during lactation. © 2009 Elsevier B.V. All rights reserved.
1. Introduction In pigs, creep feed intake during lactation is positively correlated with feed intake after weaning (Bruininx et al., 2002) and with average daily gain after weaning (Appleby et al., 1991; Bruininx et al., 2002; Pajor et al., 1991). Also net absorption in the small intestine (i.e. the net result of secretion and absorption) immediately after weaning is significantly higher in piglets consuming creep feed during lactation than in non-eating piglets (Kuller et al., 2004b), ⁎ Corresponding author. Tel.: +31 30 2532028; fax: +31 30 252 1887. 1 Present address: The Animal Health Service, Pig Health Department, Arnsbergstraat 7, Postbus 9, 7400 AA Deventer, The Netherlands.
1871-1413/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2009.08.009
thereby probably decreasing the risk of post-weaning diarrhoea. Hence, stimulating creep feed intake in suckling piglets could be important to optimize pig performance after weaning. Creep feed intake in suckling piglets is usually low during lactation but can be stimulated by intermittent suckling (IS; Berkeveld et al., 2007; Kuller et al., 2004a; Kuller et al., 2007), a management procedure in which piglets are separated from the sow for a number of hours every day during the second half of lactation. IS increases average creep feed intake per piglet and also increases the number of litters with a high feed intake during lactation (Kuller et al., 2004a). However, also during IS treatments, litters have been identified with little or no creep feed intake during lactation. Apparently, some litters
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start eating creep feed during lactation, whereas others hardly increase their feed intake when subjected to IS. In a previous experiment (Kuller et al., 2004a), we found that IS litters consuming little or no creep feed during lactation still tended to have higher feed intake and weight gain shortly after weaning than control litters with a comparable low feed intake during lactation. So, positive effects of IS on post-weaning performance may also be mediated by other factors than by increased creep feed intake during lactation alone. Little is known regarding the development of creep feed intake during lactation by individual piglets, because creep feed intake is usually determined at the litter level. One way to investigate the development of creep feed intake by individual piglets during lactation and shortly after weaning is to investigate feeder visiting behaviour by quantifying the number and duration of visits to the feeder over time. It is of interest to study the development of feeder visiting behaviour in intermittently suckled piglets, not only because IS stimulates creep feed intake during lactation but especially because it also stimulates feed intake shortly after weaning in litters with a low level of creep feed intake during lactation. We hypothesise that IS will stimulate especially piglets from low feed intake litters to visit the feeder during lactation, thereby familiarizing piglets with the feed and the feeder during lactation. In order to find out whether milk intake could have influenced creep feed intake, nursing characteristics were also studied. 2. Materials and methods 2.1. Treatments, animals and housing The experimental design was approved by the Ethical Committee of the Veterinary Faculty of Utrecht University (The Netherlands). The sows used in the current experiment were also part of another study investigating the effects of intermittent suckling on weight gain and feed intake until slaughter (Kuller et al., 2007). Sows were allotted to either a control (C) or intermittent suckling (IS) treatment. Control piglets had access to the sow for 24 h/day until weaning. IS piglets were separated from the sow for 12 h each day (0930 until 2130) and allowed access to the sow for the other 12 h (2130 until 0930). Only one treatment was applied per farrowing room to avoid an influence by suckling of control piglets on IS piglets, since suckling is highly synchronized between animals in a room. In order to synchronize the start of intermittent suckling within a farrowing room, treatment day 0 (T0) was designated as the start of data collection. Piglets were born from 1 day before to 2 day after T0. Intermittent suckling always started at T14 and piglets were weaned at T25 at 0800 a.m. During the separation period, piglets and sow remained in the pen and were separated by a removable wooden partition (height 65 cm) that was attached on both sides to the farrowing crate of the sow, not allowing any physical contact between sow and piglets. The sows were housed in farrowing crates in a farrowing pen (2.40 × 1.80 m). The farrowing pen consisted of a partly solid floor and a partly slatted floor. During the separation period, IS piglets were allowed extra space (solid floor) at the back of the pen to create comparable floor space with that of the control piglets. Lights were on between 0730
and 2330. To facilitate video recordings, a low level of light (12 lux) was maintained during the night. At weaning sows were moved to a mating room and the piglets remained in the pen. Video recordings were made of 28 sows (14 IS and 14 control). From each treatment, six sows were selected, based on feed intake level of the litter during the complete lactation period; high (H): feed intake >90 g/piglet or low (L): feed intake <85 g/piglet). So, there were 3 CH litters (n = 32 piglets; control, high feed intake level) and 3 CL litters (n = 27 piglets; control, low feed intake level), 3 ISH litters (n = 28 piglets; intermittent suckling, high feed intake level) and 3 ISL litters (n = 32 piglets; intermittent suckling, low feed intake level). Before start of IS treatment no differences were found in feed intake of the litters (CH: 24± 11 vs. CL: 18± 2 vs. ISH 23 ± 3 vs. ISL: 15± 5 g/piglet; P > 0.10) and weights (CH: 4587 ± 523 vs. CL: 5075 ± 302 vs. ISH 5500± 354 vs. ISL:4550 ± 325 g/piglet; P > 0.10) between the groups. Data of individual litters are shown in Table 1. 2.2. Piglet feeding Water was available ad libitum by means of a drinking nipple at the rear end of the pen. Creep feed residuals were weighed per litter at 7 day intervals. Because no food wastage was observed (feeder was placed on a solid floor), disappeared feed was considered eaten. Creep feed based on milk products (34%), soybeans, corn, sugar, vegetable oil and a premix (12.8 MJ NE kg− 1, 21.7% CP, 14.7% crude fat, 2.0% crude fiber, 5.2% ash, 1.46% lysine, 0.86% calcium, 0.58% phosphorus, 160 mg kg− 1 copper, 500 units kg− 1 phytase; as-fed basis) was offered to the piglets ad libitum from T7 onwards and given in a round piglet trough (diameter 25 cm). From T14 onwards a pig feeder with 4 feeding spaces was used (11 cm feeder space/piglet). From T21 to T23 a gradual change (respectively 40%, 60% and 100% replacement) was made to a weaner diet, based on milk products (18.5%), barley, soy beans, corn, sugar, vegetable oil and a premix (11.4 MJ NE kg− 1, 17.9% CP, 10.7% crude fat, 2.9% crude fiber, 5.8% ash, 1.25% lysine, 0.77% calcium, 0.59% phosphorus, 160 mg kg− 1 copper, 500 units kg− 1 phytase; as-fed basis). This was given until T31 (7 days after weaning) of the experiment. 2.3. Measurements Video recordings were made continuously for 24 h at five treatment days; T13 (day before start of IS), T16 (3 days after onset IS), T24 (day before weaning), T25 (day of weaning) and T26 (day after weaning). All piglets had been marked on their back to allow individual identification. When a piglet stayed for at least 2 s with its head in the feeder, this was recorded as a visit and beginning and end of the visit were recorded. The following parameters of feeder visiting behaviour were calculated for each piglet: total time spent at the feeder per piglet per day (total feeder time, s), visiting frequency per day and average time per visit per day (average feeder time, s). Nursing was defined as more than 50% of the litter being active (massaging or sucking) at the udder. The nursing was considered to be ended by the sow, when she turned to sternal recumbence or, in case of a nursing while standing,
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Table 1 Littersize (n), weight and feed intake level of the individual litters in high and low eating litters in the control (C) and intermittent suckling treatment (IS), means ± SE. Trt
Sow
Parity
Level
n
C C C C C C IS IS IS IS IS IS
1 2 3 4 5 6 7 8 9 10 11 12
2 2 2 8 6 2 2 6 6 8 2 2
High High High Low Low Low High High High Low Low Low
10 12 10 11 8 8 9 7 12 10 12 10
Feed intake (g/piglet)
Piglet weight (g/piglet)
T7 to T13
T14 to T24
T25 to T32 (after weaning)
Birth
Start IS
Weaning
64 42 25 16 21 17 28 23 19 10 24 10
171 471 186 10 64 67 451 219 170 41 4 14
1857 2833 1380 727 1250 888 2429 1571 1500 1643 583 750
1550 ± 40 1458 ± 21 1389 ± 24 1198 ± 20 1585 ± 32 1513 ± 40 1609 ± 46 1551 ± 36 1145 ± 20 1509 ± 27 1281 ± 32 1500 ± 36
5571 ± 169 4366 ± 124 3798 ± 176 4504 ± 89 5191 ± 146 5531 ± 137 5949 ± 174 5751 ± 211 4801 ± 131 4657 ± 98 3941 ± 93 5052 ± 138
8377 ± 243 6465 ± 196 6700 ± 84 7479 ± 116 7367 ± 239 8296 ± 217 8531 ± 187 7037 ± 298 6634 ± 151 6819 ± 124 5439 ± 110 7000 ± 187
In the intermittent suckling treatment, piglets were separated from the sow from for 12 h/day (0930 to 2130) starting 11 days before weaning (T14). Piglets were weaned at 0800 h at T25.
she started moving forwards and backwards in her farrowing crate or laying down. The nursing was considered to be ended by the piglets when, after a nursing less than 50% of the litter was active at the udder. Nursing characteristics of the litter were: total time spent nursing per day, nursing frequency and average duration of each nursing.
effects of sow (nested within treatment and feed intake level) with compound symmetry covariance structure. The model included the effects of feed intake level, treatment and day of treatment and their interactions. Bonferroni corrections were applied to correct for multiple comparisons. Data are presented as (untransformed) means ± SE.
2.4. Statistical analysis 3. Results All statistical analyses were performed using the SAS 8.2 statistical software program (SAS Institute, Inc., Cary, NC). Skewed distributions of behavioural data on feeder visits (total feeder time, average feeder time and visiting frequency) were square root transformed. Data on creep feeder visiting behaviour were analysed using a linear mixed model (West et al., 2006), allowing for repeated measurements per subject (piglet, nested within sow and treatment and feed intake level) and random effects of sow (nested within treatment and feed intake level) and piglet (nested within sow and treatment and feed intake level) with unstructured covariance structure. The model included effects of feed intake level (H vs. L), treatment (IS vs. control) and day of treatment (T13, T16, T24, T25, T26) and their interactions. Effects of gender, weight at birth or at start of treatment, and weight gain between T0 and T6 or between T7 and T13 were not significant and therefore omitted from the model. Effects of sow and feeding level were tested against the effect of sow within treatment and feeding level, so litter was the experimental unit. Time to first visit to the feeder after weaning was analysed using the survival analysis package version 2.32 of R (2006). The model included treatment and feed intake level and their interaction and litter nested within treatment and feed intake level as a random effect. Nursing characteristics were analysed using a linear mixed model (West et al., 2006) allowing for repeated measurements per subject (sow, nested within treatment and feed intake level) and random effects of sow (nested within treatment and feed intake level). Data on litter activity were analysed using a linear mixed model allowing for repeated measurements per subject (sow, nested within treatment and feed intake level) and random
3.1. Performance No difference in feed intake was found between the treatments (C: 1489 ± 314 vs. IS: 1413 ± 274 g/piglet; P = 0.75) during the first seven days after weaning (See also Table 1). However, feed intake during this week was significantly higher in litters with high creep feed intake during lactation (1928 ± 237 g/piglet) than in litters with a low creep feed intake (974 ± 163 g/piglet; P = 0.02) and the interaction of treatment × feed intake level was not significant. Weight gain during treatment was higher in control litters (C: 238 ± 6.vs IS: 172 ± 3 g/piglet/day; P = 0.03), but no difference was found between litters with different creep feed intake during lactation (H: 207 ± 5 vs. L: 202 ± 6 g/piglet/day; P = 0.86) and no interaction of treatment × feed intake level was found. After weaning, however, weight gain was lower in CL litters than in the other litters (CL:77±7 vs. CH:208±7 vs. ISL:140±6 vs. ISH: 167±8 g/piglet/day; P=0.043). 3.2. Feeder visiting behaviour 3.2.1. Lactation period (T13 to T24) A high number of CL piglets never visited the feeder during lactation; at T24, 56% of the CL piglets did not visit the feeder (Table 2). On the other hand, at T24 91% of the ISL and CH piglets and all ISH piglets visited the feeder at least once. Visiting frequency (Fig. 1) increased between T13 and T16 in ISH piglets (P = 0.0001) and between T16 and T24 in CH (P = 0.0001) and ISL piglets (P = 0.0090), but did not increase in CL piglets (P = 0.1719). At T24, visiting frequency was higher in ISL than in CL piglets.
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Table 2 Percentage of piglets with either 0, 1 to 15, 16 to 30 or more than 31 visits per 24 h to the feeder in high and low eating control and intermittent suckling piglets (IS) litters. Day
Control
IS
High (n = 32) Number of visits
T13 T16 T24 T25 T26
Low (n = 27) Number of visits
High (n = 28) Number of visits
Low (n = 32) Number of visits
0
1–15
16–30
>31
0
1–15
16–30
>31
0
1–15
16–30
>31
0
1–15
16–30
> 31
0 22 9 0 0
75 63 59 9 0
25 16 16 41 41
0 0 16 50 59
30 56 56 0 0
56 44 44 67 37
15 0 0 33 22
0 0 0 0 41
32 7 0 0 0
54 43 32 7 0
14 21 50 39 61
0 29 18 54 39
19 44 9 0 0
75 56 78 63 19
6 0 9 25 34
0 0 3 13 47
In the IS treatment, piglets were separated from the sow for 12 h/day (0930 to 2130) starting 11 days before weaning (T14). Piglets were weaned at 0800 h at T25.
An increase in average feeder time (Fig. 1) was found between T16 and T24 in IS piglets (P < 0.05), but not in control piglets. Between T16 and T24, total feeder time increased in piglets from all groups (P < 0.05), except in CL piglets in which no change was found (P > 0.10). At T16 and at T24, total feeder time was higher in H piglets than in L piglets. 3.2.2. After weaning (T25 and T26) No differences were found between the treatments or between the feed intake levels in latency to first visit to the feeder after weaning (Fig. 2; Mean: ISH: 1.8 ± 0.2; CH: 2.3 ± 0.3; ISL: 5.8 ± 1.0; CL: 4.1± 0.7 h). Low feed intake piglets went for the first time after weaning to the feeder as litter (ovals in Fig. 2), in high feed intake litters this effect could not be discriminated. All piglets had visited the feeder at T25 and T26 (Table 2). Also the percentage of piglets visiting the feeder with a high frequency (>31 visits per day) increased after weaning, although it took until T26 before this high frequency of visits was seen in CL litters. Visiting frequency was higher in H than in L piglets at T25 (Fig. 1), but did not differ between treatments at T26. Total feeder time (Fig. 1) increased over time for all groups (P < 0.05). At T26, CL piglets had a lower total feeder time than piglets from the other treatments (P = 0.0001). 3.3. Nursing characteristics Once IS treatment had started, nursing frequency (Table 3) was lower in IS litters than in control litters. Within treatments, no differences were found in nursing frequencies for litters with high and low feeding level. Although average nursing time was often shorter in H than in L litters, this only resulted in a difference in total nursing time between H and L litters in the control group at T16 and T24 and not in the IS group. 4. Discussion It is known that IS increases feed intake before and after weaning (Kuller et al., 2004a; Berkeveld et al., 2007). In these studies some 60% of the IS litters, against 20% of the control litters, had an average feed intake per piglet of more than 600 g before weaning. So, the number of litters with high feed intake during lactation increased and the number of litters with low creep feed intake decreased by IS. Some litters could
not be stimulated by IS to consume a considerable amount of creep feed (Kuller et al., 2007). The current experiment showed, however, that IS also has a positive effect on litters with low feed intake during lactation. One day before weaning, piglets from low feed intake litters in the IS treatment had a higher visiting frequency than piglets from low feed intake litters in the control treatment. Further, visiting frequency and total feeder time increased in ISL piglets between T16 and T24, while in CL piglets no increase was seen during lactation. Also on the second day after weaning, total feeder time was higher in ISL than in CL piglets. It has been reported that piglets, placed in an unfamiliar environment and offered an unfamiliar source of feed after weaning, do not consume enough feed to meet energy requirements (Bark et al., 1986). Also other authors (Pluske and Williams, 1996) suggested that low feed intake levels by newly weaned piglets may be related to unfamiliar feeders. Pre-exposure to the smell or presence of novel food can reduce neophobia to the food (Nicol and Pope, 1994), which probably facilitates feed intake and thus weight gain after weaning. The difference in feeder visiting behaviour between ISL and CL litters in the our experiment might explain why in a previous study (Kuller et al., 2004a) we found that IS litters with a low creep feed intake during lactation had a higher feed intake and a higher average daily gain after weaning than control litters with a comparable feed intake during lactation. Although feed intake was very low in all L litters, including the ones exposed to the IS treatment, the feeder visiting behaviours and sampling of small amounts of feed may have prepared the piglet both behaviourally and physiologically, for the post-weaning situation (Brooks and Tsourgiannis, 2003; Petersen, 1994). The IS treatment did not affect feeder visiting behaviour of piglets with a high level of feed intake during lactation. Piglets in litters with a high feed intake had similar eating behaviour in the IS treatment and the control treatment, and this behaviour differed from L piglets both during and after lactation in a way that both visiting frequency and total feeder time were higher in H litters. Visiting frequency increased during lactation in H litters, which is in agreement with others (Delumeau and Meunier-Salaun, 1995; Wattanakul et al., 2005) who found that the number of creep feeding acts increased over time in the 3rd and 4th week of lactation. Like in previous studies, total feeder time increased by the end of lactation (de Passillé et al., 1989; Mason et al., 2003) and after weaning (Algers et al., 1990; Dybkjaer et al., 2006; Mason et al., 2003;
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Fig. 1. Visiting frequency, average feeder time and total feeder time in high (solid line, closed symbols) and low (dotted line, open symbols) eating litters in the control (circles) and intermittent suckling (triangles) treatment at different treatment days (24 h). In the control treatment piglets were continuously with the sow. In the intermittent suckling treatment, piglets were separated from the sow from for 12 h/day (0930 to 2130) starting 11 days (T 14) before weaning. Piglets were weaned at 0800 h at T25. Data are presented as means ± SE. Within a treatment day, different letters indicate significant differences between groups.
Morgan et al., 2001) in H piglets. It is known that piglets that start eating during one day will continue to do so on the next day (Appleby et al., 1991; Pajor et al., 1991), implying that piglets in high eating litters will probably not stop visiting the feeder and will continue eating after weaning. Therefore, it is less likely that they will encounter problems that are associated with low feed intakes after weaning, like a growth check or diarrhoea. After weaning, latency to first visit to the feeder did not differ between the groups in our experiment. Bruininx et al.
(2002) found that the number of piglets that did not eat after weaning declined faster in piglets with known creep feed intake before weaning than in non-eaters. However, he also found that the number of visits to the feeder after weaning did not differ between so called ‘eaters’ and ‘non-eaters’, but that the number of visits during which feed was consumed was higher in eaters. Therefore, it was suggested that piglets that are familiar with food at the moment of weaning (eaters) are more efficient in their food intake than piglets that are unfamiliar with the food (non-eaters). Thus, latency to first
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Fig. 2. Percentage of piglets that had not visited the feeder after weaning as a function of post-weaning interval. Ovals indicate piglets of the same litter. In the control treatment piglets were continuously with the sow. In the intermittent suckling treatment, piglets were separated from the sow from for 12 h/day (0930 to 2130) starting 11 days before weaning (T14). The experiment started at treatment day 0 (T0). Piglets were weaned at 0800 h at T25. Lights were turned off, at 15 h after weaning.
Table 3 Nursing characteristics of high and low eating litters in the control and intermittent suckling (IS) treatment. Nursing
Day2
Control1
IS1
High Mean Frequency
Average time (min)
Total time (min/day)
1
T13 T16 T24 T13 T16 T24 T13 T16 T24
28 30a 26a 5.4a,x 4.4a,x 3.5a,y 153x 129a,x 90a,y
Low SE 2 1 1 0.5 0.2 0.3 9 5 3.6
Mean 27 25a 27a 6.7a 6.5b 5.2b 181x 163b,x 144b,y
High SE 2 1 3 0.1 0.2 0.4 17 6 26
Mean x
32 19b,y 19b,y 4.9b,x 4.8a,x 5.5b,y 155x 89c,y 103a,y
Low SE 1 2 0 0.3 0.4 1 4 11 17
Mean x
30 20b,y 20b,y 5.3a 5.7b 5.8b 156x 113 ac,y 114a,y
SE 0 1 2 0.3 0.5 0.6 8 12 7
In the control treatment, piglets were continuously with the sow. Piglets in the IS treatment were separated from the sow for 12 h/day (0930 to 2130) beginning at treatment day 14 (T14). 2 T13 = day before start of IS; T16 = 3rd day of IS; T24 = day before weaning. a,b Within a row, means with a different superscript differ (P < 0.05). x,y Within a column, means with a different superscript differ (P < 0.05).
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visit to the feeder may not be a good parameter to distinguish eaters from non-eaters. Remarkably, low feed intake piglets went for the first time to the feeder after weaning as a litter. This could be the result of the synchronization of behaviour and nursings during lactation. Suckling behaviour is highly synchronized around nursings, which is mainly controlled by the sow's milk let down (Fraser, 1980). The synchronization of suckling leads to a concomitant synchronization of activity and inactivity and also programs litters to feed as a group (Brooks and Burke, 1998). This likely continues shortly after weaning. In addition, also feeding-related behaviours are often highly synchronized and socially facilitated in pigs (Hsia and Wood-Gush, 1982; Hsia and Wood-Gush, 1984). Feeder visiting behaviour was highly variable between piglets and litters and this has been related to differences in milk production by the sow (Delumeau and Meunier-Salaun, 1995). In our experiment, a difference in milk availability was imposed by denying access to the udder for 12 h/ day in the IS treatment. IS litters could only partly compensate these 12 h of separation by increasing suckling frequency or average nursing time in the hours that they had access to the sow. Although the effect of separation of piglets and sow on milk production is unknown, it is likely that milk intake of the piglets is decreased since IS piglets are lighter at weaning than continuous suckled piglets (Kuller et al., 2004a; Kuller et al., 2007). This decreased milk intake might have motivated the piglets to increase solid food intake as stated by others (Puppe and Tuchscherer, 2000). 5. Conclusion IS stimulated piglets from litters with a low level of creep feed intake to visit the feeder during lactation, which familiarized them with the feeder and the feed during lactation. The IS treatment did not affect feeder visiting behaviour of piglets with an anyhow high level of feed intake during lactation. References Algers, B., Jensen, P., Steinwall, L., 1990. Behaviour and weight changes at weaning and regrouping of pigs in relation to teat quality. Applied Animal Behaviour Science 26, 143–155. Appleby, M.C., Pajor, E.A., Fraser, D., 1991. Effects of management options on creep feeding by piglets. Animal Production 53, 361–366. Bark, L.J., Crenshaw, T.D., Leibbrandt, V.D., 1986. The effect of meal intervals and weaning in feed intake of early weaned pigs. Journal of Animal Science 62, 1233–1239. Berkeveld, M., Langendijk, P., Bolhuis, J.E., Koets, A.P., Verheijden, J.H.M., Taverne, M.A.M., 2007. Postweaning growth check in pigs is markedly
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