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Influence of weather on the behaviour of outdoor-wintered beef cattle in Scandinavia
Livestock Science 136 (2011) 247–255
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Livestock Science j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / l i v s c i
Influence of weather on the behaviour of outdoor-wintered beef cattle in Scandinavia Katharina L. Graunke a,⁎, Tibor Schuster b,1, Lena M. Lidfors a,2 a b
Department of Animal Environment and Health, Swedish University of Agricultural Sciences, P.O. Box 234, SE-532 23 Skara, Sweden Institute of Medical Statistics and Epidemiology, Klinikum rechts der Isar der Technischen Universität München, Munich, Ismaninger Str. 22, 81675 München, Germany
a r t i c l e
i n f o
Article history: Received 13 October 2009 Received in revised form 17 September 2010 Accepted 18 September 2010 Keywords: Cattle Behavior Temperature Wind Outdoor Winter
a b s t r a c t The aim of the present investigation was to study the effect of weather and available protection on the behaviour of outdoor-wintered beef cattle (Bos taurus). A herd of 78–85 cattle head was studied during four winter months in the Southwest of Sweden. Protection was offered by coniferous forest situated on and around the 12 ha pasture, which we divided into protection categories. During 240 h we observed 10 cows and 10 heifers as focal animals (each 3 h/month) during day time and adjusted observation times to the altitude of the sun. Close to the animals and at an unprotected spot of the pasture we measured temperature, wind speed and solar radiation and combined these variables to a single measure called Wind Chill Temperature (WCT). During observations the animals were in the forest in 12.4%, near protection in 10.4% and without protection in 77.2% of the recordings. During precipitation, i.e. rain, snow and hail, the animals frequented the forest 2.71 times more often than during dry weather; however, only in 17.0% of the hours with precipitation the focal animals were in the forest. In 75.0% of the observation hours the WCT in the animals’ surrounding was at least 2 °C higher than at the most exposed spot of the pasture. Without precipitation the animals were lying less, feeding more and ruminating less at low WCT. During precipitation they were lying more, feeding less and ruminating more at low WCT. The lower the WCT and the higher the wind speed the more subjects there were within a 5 m-radius around the focal animal. The results indicate that the cattle adjusted their behaviour to both WCT and precipitation, that they were able to find warmer microclimates even without always having to frequent protecting objects, and that conspecifics were used as protection. © 2010 Elsevier B.V. All rights reserved.
1. Introduction A central factor for endothermic animals in coping with their environment is temperature which is especially important
⁎ Corresponding author. Present address: Leibniz Institute for Farm Animal Biology (FBN), Research Unit Behavioural Physiology, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany. Tel.: + 49 38208 68 823; fax: + 49 38208 68 802. E-mail addresses: [email protected] (K.L. Graunke), [email protected] (T. Schuster), [email protected] (L.M. Lidfors). 1 Tel.: + 49 89 4140 4324. 2 Tel.: + 46 511 67 215. 1871-1413/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2010.09.018
during winter. When temperature falls below the Lower Critical Temperature (LCT) animals must increase their metabolic heat production by shivering or other thermogenetic processes to keep up their body temperature (e.g. Christopherson, 1985; Eckert et al., 2000). At lower temperatures cattle have a greater need for energy (e.g. Fox et al., 1988; Young, 1975) and need to feed more (e.g. Fox et al., 1988; McDowell et al. 1976; Olbrich et al., 1973). The higher demand for energy may even result in weight loss (Christopherson, 1985; Webster, 1971). The LCT varies greatly depending on the stage of reproduction and physical conditions like coat length or fat layer (Christopherson, 1985). Investigations of the LCT usually have been determined on single-kept animals in restricted environments like stalls
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and climatic chambers (Christopherson, 1985). Therefore neither effects of a group nor wind, precipitation or radiation have been incorporated in the LCT (Christopherson, 1985). The temperature animals experience is the Effective Environmental Temperature which is influenced by environmental factors that include heat loss by conduction, radiation and convection (Baker, 2004). Increasing wind speed decreases the experienced temperature whereas solar radiation increases it (Environment Canada, 2003). Precipitation, primarily rain, reduces the insulation capacity of a coat (Young et al., 1989) and furthermore cools the insulating air layer within the coat by evaporation (Eckert et al., 2000). Cattle have a very strict diurnal behaviour pattern. Being crepuscular animals grazing peaks occur around sunrise and sunset whereas there is low activity at midday (Arnold and Dudzinski, 1978; Fraser, 1983; Hafez and Bouissou, 1975). Therefore grazing in cattle is adjusted to sunlight (Hughes and Reid, 1951) which plays a very important role for the daily pattern especially in the northern countries where the day length and intensity of solar radiation are much less in winter than in summer. Other behaviours are influenced by the grazing pattern (Hafez and Bouissou, 1975) so that possibly the time with a low activity level during midday might decrease in length or even disappear during very short winter days. The ability to learn allows animals to behaviourally adjust to their particular environment (Franck, 1979). Beaver and Olson (1997) found that experienced beef cows grazed more
frequently in areas that were protected from weather than inexperienced cows. Waßmuth (2003) therefore suggests that heifers should be raised outdoors and that cows have to be brought to their winter pasture early enough to acclimate to the (weather) conditions. Little is known about the type of protection cattle choose when performing different behaviours and if that choice is dependent on weather. The aim of this study was to investigate the effect of temperature, wind speed, solar radiation and precipitation on behaviour and the use of natural protection of outdoorwintered cattle (Bos taurus) with varying experience. We predicted that cattle would prefer to rest well protected from wind and precipitation, that they would feed and ruminate more in cold weather, and that they would lie more in warm sunny and cold snowy weather. Furthermore we expected that more experienced cattle would seek protection more effectively and react faster to weather changes. 2. Materials and methods 2.1. Materials The study was carried out in the Southwest of Sweden (58°19′ N, 13°29′ E) on a slightly hilly pasture of 12 ha (130 m above sea level) with 10 m altitude difference. Coniferous forest covered about 1/3 of the pasture and deciduous and coniferous forest surrounded it at three sides (Fig. 1). The
Fig. 1. Map of the study field with available protection; the permanent green marks forest the animals could go into. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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studied herd consisted of 78–85 adult beef cattle head of different breeds and their crossbreeds and up to 50 calves. The cattle were fed grass silage mostly at noon three times per week. They had ad libitum access to the silage from three movable feedracks. Protocol and conduct of this study were approved by the Ethical Committee on Animal Experiments, Gothenburg.
Table 1 Definition of the recorded body positions and behaviours of beef cattle kept outdoors during winter time. Parameters Body position Standing Walking Running Lying Behaviour Feeding
2.2. Methods Ten cows (5–10 years) and 10 heifers (3 years) of Black Angus–Charolais-crossbreed or Black Angus were randomly selected. The herd had experienced at least two winters in the area and was used to the weather conditions at these latitudes. The focal cows weighed 625 kg (SD ± 34 kg) on average throughout the winter whereas the heifers weighed 561 kg (SD ± 61 kg). The most frequent body condition score in the focal animals was 4.0 (as was the mean) at measurements at the start, the middle and the end of the experiment (1.0:= “severe under-conditioning” to 5.0:= “severe overconditioning”, after Edmonson et al., 1989). At each measurement half of the cows had a body condition score of 4.5 whereas the most frequent body condition score in the heifers was 4.0 (six heifers at the start and middle measurement and four at the end, 4.0:= “frame not as visible as covering”). At the beginning of the observations all focal animals except for three heifers were pregnant. After one month of observations a non-pregnant heifer had to be replaced with a pregnant substitute heifer due to injury. We divided the pasture into the protection categories: “In forest”, “Near protection” and “No protection”. Groves, stone walls, bushes, solitary trees and forest could offer protection. Depending on size and height a distance of 5–10 m to the protecting object was allowed to be called “Near protection”. According to wind direction the category “Near protection” was classified as “leeward” or “windward” during observations. See Fig. 1 for available protection. Observations were made during 15 days/month from December 2006 to March 2007 by the same trained observer who observed in total 240 h. Every focal animal was observed in total 12 h, 3 h/month and 1 h/observation, which means that behavioural recordings on each individual were repeated three times per month. The repetitions within each month were carried out at different times and days after a randomly made time table. Each day observations were made 2 h in the morning and 2 h in the afternoon; one cow and one heifer each were observed every morning and every afternoon. Feeding usually took place in between morning and afternoon observations. Observation times were adjusted to the altitude of the sun. Morning observations began 15 min after sunrise and afternoon observations 70 min after solar noon to cover most of the daily activity. The number of animals in a two-cow-lengths-radius (ca. 5 m) around the focal animal's head was recorded. We assumed that the more individuals there were within the radius, the shorter the distance was between the animals in the group. Body position and behaviour (Table 1), protection category and animals in the two-cow-lengths-radius were recorded instantaneously at 4-min intervals. Some behaviours can be performed in different body positions. In this study, the term
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Ruminating No activity Other
Definition At least 3 legs touch ground, no forward movement Max. 3 legs touch ground, forward movement Max. 2 legs touch ground, fast forward movement Body touches ground, no weight on legs Picking, chewing or swallowing silage or vegetation or sucking and swallowing water Regurgitating or chewing on partly digested food No visible activity, no vigilance or exploring All other behaviour not named above
“behaviour” included all possible body positions within this behaviour and with the term “body position”, all possible behaviours were included, if not stated otherwise. For part of the analyses we summarised the behaviours ruminating and no activity to a new parameter called “resting” which can be performed both standing and lying. Directly after each behavioural recording at 4-min intervals temperature, wind speed and solar radiation were measured with a portable weather station (PWS) (LM-8000, Lutron Electronic Enterprise Co., Taiwan) at 1.1 m above the ground within the two-cow-lengths-radius of the focal animal and precipitation (rain, snow, hail) was noted. A stationary weather station (SWS) (WXT 510, Vaisala, Finland) was placed at an open spot of the pasture without protection from weather (Fig. 1). Both weather stations were tested for similarity in their measurements in the field. Due to the availability of data from the weather stations, the number of observation hours with weather data ranges between 205 and 238. For statistical analyses weather data was combined to a single measure called Wind Chill Temperature (WCT) given in °C for each weather station. An equation developed by Environment Canada (2003) and modified by Tucker et al. (2007) was used:
W
13.12+ 0.6215 × Tair − 13.17 × V 0.16 + 0.3965 × Tair × V 0.16 wind chill index based on °C
Tair
air temperature in °C
V
wind speed in km/h
W
When the wind speed is 0.72 km/h or below this equation would add some units to the temperature and hence in this case the original temperature was used as wind chill index W. According to Environment Canada (2003) bright sunshine might reduce the effect of wind chill by 6–10°. The observer noted that a bright cloudless winter day in the pasture's latitude never had a light intensity below 20 000 lx and a sunny day with some clouds never had a light intensity below 15 000 lx. Light intensity of the stationary weather station was measured in kW/m² which is not convertible into lux. Thus values in lux taken from the portable weather station next to the stationary weather station were compared with measures from the stationary weather station in kW/m² taken at the same time. 15 000 lx corresponded roughly with
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0.1 kW/m² and 20 000 lx with 0.2 kW/m². Therefore the following modifications were done for this study: IF V ≤ 0.72 km/h THEN W = Tair IF solar radiation ≥ 15 000 lx (PWS) OR 0.1 kW/m² (SWS) THEN WCT = W + 6 IF solar radiation ≥ 20 000 lx (PWS) OR 0.2 kW/m² (SWS) THEN WCT = W + 10 Otherwise WCT = W 2.3. Statistics For statistical analyses all measures were combined per observation hour except for the percentage of lying and resting standing in different protection categories which was calculated per animal. A mean value per hour was calculated of the temperature, wind speed, WCT and of the number of animals in the two-cow-lengths-radius of the focal animal. Protection categories were given codes which became higher the less protection the category offered (1:= “In forest”, 2:= “Near protection, leeward”, 3:= “Near protection, windward”, 4:= “No protection”). The median value of the code was calculated per observation hour which gave information of what protection category the animals stayed in the most. The number of recordings of each body position and behaviour were summed per hour. An observation hour was declared as “with precipitation” when at least one precipitation event occurred, since wet or snow-covered ground might influence the animals’ behaviour. Statistical analyses were done with SPSS 15.0 (SPSS Inc., USA) and R version 2.5.1 (The R Foundation for Statistical Computing, Austria). To evaluate differences in the use of the four protection categories we summarized the number of observations in the different protection categories per animal (only those who were observed all four months, n = 19) and conducted the Friedman two-way analysis of variance by ranks (df = 3). Pairwise differences between protection categories as well as differences in weather data from the two stations (number of observation hours: 205 for WCT and temperature, 206 for wind speed) were tested with the Wilcoxon signed ranks test (two-tailed). To estimate the influence of different factors on the response variables we used Generalized Linear Mixed Models (GLMM) to consider time-dependent autocorrelation of repeated observations within the same animal. For count data a Poisson-regression model-link was used and logistic regression model-link functions for multinomial data with the reference category “No protection”. Tested explanatory variables were WCT and wind speed of PWS and SWS, precipitation, age group and month. GLMM regression coefficients (transformed by the exponential function: ecoefficient) give an estimate for the mean relative change (denoted as “factor”) of outcome measure by a one-unit increment of the corresponding explanatory variable or category and are provided with 95% confidence intervals (CI). Factor “1.00” means there is no effect on the response (e.g. the number of feeding events per hour) by the appropriate variable (e.g. the WCT). A factor smaller than 1.00 means the response becomes smaller by the factor per unit (e.g. per 1 m/s) or category (e.g. per protection category), a factor bigger than 1.00 makes the response bigger by the
factor per unit or category. Confidence intervals excluding factor 1.00 depict a statistically significant relationship of response and explanatory variable. All statistical tests were performed two-tailed and a p-value b 0.05 was considered to indicate statistical significance. To retain a maximum of power and to avoid overconservatism in the primary interesting analyses, no correction for multiple testing (increment of false positive results with the number of statistical tests being conducted) was performed. However, according to Saville (1990) an informal adjustment for multiple comparisons may be conducted by the reader based on the results (particularly the number of statistical tests) which are thoroughly provided in the text. 3. Results 3.1. Weather and its general impact on behaviour February was the coldest month and March was the warmest month (Table 2). The difference of WCT between morning and afternoon was largest in March (7.3 °C) when days became longer and the sun's zenith higher and was smallest in December (1.4 °C) when days were shortest and the sun's zenith lowest. The animals were standing in 79.8% of the recordings, lying in 13.4%, walking in 6.7% and running in 0.1%. They were lying 6.0 percentage points more in the morning than in the afternoon. Differences during the day were largest in February when the cattle were lying 29.3% of the recordings in the morning whereas only 3.6% in the afternoon. They then walked more than twice as much during afternoons (8.2%) compared to mornings (4.0%). The animals were feeding in 35.6%, ruminating in 27.0%, showing no activity in 19.5% and showing other behaviour in 17.9% of the recordings. The mean WCT was higher in the surrounding of the focal animal (PWS) than at the stationary weather station (SWS) in 90.2% of the observation hours (P b 0.001). In 95.6% of the observation hours temperature was higher (P b 0.001) and in all hours wind speed was lower around the focal animal than at the SWS (P b 0.001). Compared to the stationary weather station mean values at the portable weather station were 1.8 °C higher for temperature and 3.7 °C for WCT and 1.7 m/s lower for wind speed (Table 3). In 19 of 205 hours the WCT at the SWS was higher than in the focal animals’ surrounding (PWS) and in 17 of these 19 hours the cattle were at spots of the pasture where solar radiation was lower than at the exposed spot where the SWS was situated (e.g. in the forest). In 2 of the 19 hours there was partly drizzle at average temperatures of 5.6 °C and 5.0 °C.
Table 2 Mean ± SD of Wind Chill Temperature (WCT) in °C, temperature in °C and wind speed in m/s at the stationary weather station during the four observation months.
December January February March
WCT
Temperature
Wind speed
−2.7 ± 3.4 −5.1 ± 4.8 −7.6 ± 6.3 2.3 ± 5.6
1.4 ± 4.3 0.2 ± 4.3 −3.3 ± 4.0 4.0 ± 3.0
2.4 ± 1.9 3.3 ± 2.1 2.5 ± 1.5 3.0 ± 1.5
K.L. Graunke et al. / Livestock Science 136 (2011) 247–255 Table 3 Mean ± SD, minimum and maximum of temperature and Wind Chill Temperature (WCT) in °C (number of observation hours: 205) and of wind speed in m/s (number of observation hours: 206) for portable (PWS) and stationary weather station (SWS) calculated from means per observation hour during four winter months. Mean ± SD
Temperature WCT Wind speed
Minimum
Maximum
PWS
SWS
PWS
SWS
PWS
SWS
2.3 ± 5.0 0.4 ± 5.9 1.2 ± 1.0
0.5 ± 4.8 −3.3 ± 6.6 2.9 ± 1.8
−11.6 −16.9 0.0
−12.5 −22.7 0.4
13.8 21.0 6.6
11.3 16.6 9.4
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P = 0.018). There was a tendency to use the category “Near protection, windward” 3.52 times more often during precipitation (factor: 3.52, CI: 0.95–13.02, P = 0.060). Precipitation did not significantly influence the use of the category “Near protection, leeward”. WCT had no significant impact on the use of the protection categories. 3.4. Impacts on body position and behaviour
Lying differed significantly among the protection categories (P b 0.001), but there was no significant difference in the recorded number of lying behaviours between “No protection” and “In forest” (Fig. 2). The animals were hardly lying “Near protection” (Fig. 2). When the proportion of lying per category was compared it was significantly higher “In forest” (41.2%, P = 0.002) than in ”No protection” (8.6%). Resting (ruminating and no activity while standing or lying) differed significantly among the protection categories (P b 0.001, Fig. 2). The animals rested unprotected in significantly more recordings than in the forest (P b 0.001, Fig. 2). The cows and heifers were in 12.4% of the recordings in the forest, in 5.9% “Near protection, leeward”, in 4.5% “Near protection, windward” and in 77.2% unprotected (Fig. 2). When resting in the forest, the animals were lying in 54.8% of the recordings, whereas when resting unprotected the percentage of lying was only 21.3% (Fig. 2).
Decreasing WCT influenced lying, feeding and ruminating differently depending on if there was no precipitation or if there was precipitation. The higher the WCT the more the animals were lying when there was no precipitation (factor: 1.19/°C, CI: 1.14–1.25, P b 0.001, Fig. 3a). When there was precipitation the animals were lying the more the lower the WCT was (factor: 0.90/°C, CI: 0.87–0.93, P b 0.001, Fig. 3a). In total the animals were lying nearly ¼ less during precipitation than when no precipitation (factor: 0.76, CI: 0.61–0.94, P = 0.012). The lower the WCT the more the animals were feeding when there was no precipitation (factor: 0.92/°C, CI: 0.89–0.95, P b 0.001, Fig. 3b). When there was precipitation the animals were feeding the more the higher the WCT was (factor: 1.05/°C, 1.03–1.08, P b 0.001, Fig. 3b). In total the animals were feeding ¼ less during precipitation than when no precipitation (factor: 0.75, CI: 0.65–0.86, P b 0.001). The higher the WCT the more the animals were ruminating when there was no precipitation (factor: 1.07/°C, CI: 1.03–1.10, P b 0.001, Fig. 3c). When there was precipitation the animals were ruminating the more the lower the WCT was (factor: 0.96/°C, CI: 0.94–0.98, P b 0.001, Fig. 3c). In total the animals tended to ruminate more during precipitation than when no precipitation (factor: 1.12, CI: 0.98–1.29, P = 0.095).
3.3. Use of protection
3.5. Conspecifics as protection
In 36.7% of the observation hours there was at least one interval with precipitation. In 17.0% of those hours the focal animal was mainly in the forest. The forest was used 2.71 times more often when there was precipitation than when there was no precipitation (factor: 2.71, CI: 1.19–6.20,
The lower the WCT the more animals there were in the radius of the focal animal (factor: 0.98/°C, CI: 0.97–0.99, P b 0.001, Fig. 4). With every successive observation month the number of animals in the radius of the focal animal decreased with more than ¼ (factor: 0.74/month, CI: 0.64– 0.84, P b 0.001). The higher the wind speed the more animals there were in the focal animal's radius (factor: 1.08/m/s, CI: 1.03–1.14, P = 0.002, Fig. 4). When unprotected the cows and heifers had almost 1.45 times as many animals in their radius than in the forest (factor: 1.13/protection category, CI: 1.05– 1.23, P = 0.002). Precipitation had no significant impact on the number of cattle in the focal animals’ radius.
3.2. Choice of resting spots standing and lying
100 90 80
Percentage
70 60 50
3.6. The role of experience
40 30 20 10 0 Total
In forest
Not resting
Near Near No protection, protection, protection leeward windward Resting standing Lying
Fig. 2. Percentage of recordings of not resting, resting standing and lying in total and in the different protection categories of outdoor-wintered beef cattle (n = 19).
Heifers tended to be in the forest 2.33 times more often than cows (factor: 0.43, CI: 0.18–1.01, P = 0.053) and tended to use the category “Near protection, leeward” 3.45 times more often than cows (factor: 0.29, CI: 0.07–1.19, P = 0.085). The difference between WCT of PWS and SWS showed no differences between the cows and heifers in median and quartiles (Fig. 5), merely the upper whisker and the distribution of outliers were different. In 75.0% of the observation hours the cattle were in microclimates where WCT was at least 2 °C warmer than where the SWS was placed regardless of protection category.
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Wind speed portable weather station in m/s
No. of animals in the 5 m-radius of the focal animals
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WCT portable weather station in °C Fig. 4. Estimated mean number (with 95% confidence bands) of other cattle in the radius of the focal animals at different Wind Chill Temperatures (WCT) (grey filled plane with solid boundaries) and different wind speeds (blank plane with dotted boundaries) of the portable weather station calculated on base of the Poisson-regression model. The axes cover the range of minimum and maximum of the variables (number of observation hours: 238).
Heifers were lying 2.22 times more often than cows (factor: 0.45, CI: 0.21–0.95, P = 0.037), but ruminating and feeding did not significantly differ between cows and heifers. The number of animals in the radius of the focal animals did not significantly differ between cows and heifers.
4. Discussion The animals in this study were standing a large (79.8%) and lying a small proportion (13.4%) of the observations which were made during daylight. This is similar to what has been found in the free living Chillingham cattle in northern England which were standing 71.4% and lying 14.9% during daylight (Hall, 1989). Walking played a much bigger role in the Chillingham cows (13.1% (Hall, 1989) vs. 6.8% in this study), most probably because the study included summer when the cattle were grazing whereas in this study the animals had ad libitum access to silage during observations and were in no need of searching for pasture. The big difference in the apportionment of body positions between morning and afternoon in February may result from the cold Fig. 3. Estimated mean number (with 95% confidence bands) of recordings per observation hour of a) lying, b) feeding and c) ruminating of beef cattle kept outdoors during winter at different Wind Chill Temperatures (WCT) of the portable weather station during precipitation (solid lines, grey filled planes) and without precipitation (dashed lines, blank planes), calculated on base of the Poisson-regression model. The axes cover the range of minimum and maximum of the variables (number of observation hours: 238 for lying and ruminating; 205 for feeding).
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12
Difference of WCT between portable and stationary weather station in °C
11 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 Heifers
Cows
Fig. 5. Difference of the Wind Chill Temperature (WCT) between the stationary and portable weather station in °C shown for heifers and cows (medians, 5th, 25th, 75th and 95th percentiles, *: outliers; number of observation hours: 205).
mornings (mean temperature −4.1 °C, SD ± 3.9 °C, mean WCT −9.8 °C, SD ± 5.7 °C) and could be interpreted as a reaction to cold as Redbo et al. (1996) found that outdoorwintered dairy steers were lying more during cold days. Redbo et al. (1996) also associated increasing temperature with increasing movement which is in accordance with our observations of high percentages of walking in February afternoon when it was warmer than in the mornings. The cows and heifers in this study were in areas with a higher WCT than at the SWS during more than 90% of the observations. This was often due to the wind speed being lower where the cows and heifers were, compared to the open area where the SWS was placed. However, 14 of the 20 focal cows and heifers were observed to be in areas which had lower WCT than at the SWS during one or two observation hours. Thus, the cattle were obviously in no need to find warmer microclimates during those hours. The WCT in these hours never came close to −13 °C which has been reported to be the LCT in beef cows in early pregnancy (Christopherson, 1985). On these occasions the animals were often standing in the forest where light intensity was lower than in the open field which changed the WCT. In this study the cattle were rather standing than lying when resting unprotected. One reason for this may be their inability to flee or scare off predators instantly when lying, as the standing up-process takes several seconds (Gustafson and Lund-Magnussen, 1995; Wechsler et al., 2000). Without protection animals are easier spotted and reached than in the forest. Resting includes sleep (lying) and a half-asleep dozing state (lying and standing) which cattle often reach while ruminating (Phillips, 2002). In those states they perceive their environment subdued and possible danger
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might not be noticed right away. From inside the forest (10 m and more from the edge) the outside-surrounding is quite easily observed, whereas from the outside details in the darker inside can hardly be seen. Animals inside the forest therefore have additional time to react before they are spotted which is especially important while lying. This could be the reason for why the animals were more often standing than lying when resting without protection. The animals in this study were seeking protection more often when there was precipitation, although they were unprotected during 83.0% when this occurred. However, precipitation was slightly overstated since an hour was classified as “with precipitation” as soon as it occurred once, no matter of duration and intensity. If duration and especially intensity were regarded, results might have been different, yet this was not possible in this study. Vandenheede et al. (1995) reported a significantly higher occupation rate of a human-built shelter without bedding by fattening beef bulls from 0.4 mm rain per hour and from at least 2 h duration. They mentioned that rain with lower intensity or shorter duration could be pleasant for cattle. However, their study was made during the summer with 14.1 °C mean temperature. Shorter less intense rain at lower temperatures may have the same effect on the animals as longer more intense rain at higher temperatures, whereas snow might have a quite different influence; Wagner (1988) drew similar conclusions. Snow at lower temperatures is rather dry and animals might not be as affected as by rain. The study by Vandenheede et al. (1995) did not regard wind speed which is an important factor in thermal stress particularly in combination with rain (Christopherson, 1985). The finding in the presented study that the animals were lying less during precipitation regardless of the WCT and more at lower WCT while precipitation shows that the cattle tried to lie less when it was wet on the ground. Wassmuth et al. (1999) observed similar behaviour. Schütz et al. (2010) found that rain decreased the duration of lying in dairy cattle kept at a mean temperature of 10 °C. When cattle were feeding often as a consequence ruminating occurred little and vice versa. Therefore feeding and ruminating were opposite to each other. At lower temperatures animals have a greater need for energy (e.g. Fox et al., 1988; Young, 1975) and need to feed more (e.g. Fox et al., 1988; McDowell et al., 1976; Olbrich et al., 1973). Another explanation for our observation of more feeding at lower WCT is day length. Higher WCT occurred mainly during March when the median day length was 680 min (December–February median day length 456 min). As cattle mostly feed during daylight and twilight (e.g. Arnold and Dudzinski, 1978; Hafez and Bouissou, 1975; Hancock, 1950) they had about 4 h more time to feed in March when WCT was quite high. Then they had time for a midday rest as described by Fraser (1983) and Hafez and Bouissou (1975). During December and January observations not only began with daybreak (like in February and March) but also ended with dusk and therefore covered most of the daylight period except for 90–120 min around noon. Feeding was probably mainly compressed into the short day and longer breaks could not be afforded. An estimated higher number of recordings of feeding was the result and therefore rumination had to be opposed. Food was only provided in the category “No protection”. During precipitation the categories
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“In forest” and “Near protection, windward” were frequented with a higher probability when compared to “No protection”. As a result the animals were more likely to ruminate than to feed during precipitation. There were more animals in the radius of the focal animals in this study the higher the wind speed, the lower the WCT and when they were unprotected. Mammals living in groups often huddle together to conserve warmth (Mendl and Held, 2001). In the forest the subjects could not crowd together as easily as outside and it might not have been as important, since trees protect from wind and precipitation. Bodies break the wind and can by that protect from it; therefore having more animals around gave the individual protection from wind. Olson and Wallander (2002) found that cattle spent more time behind windbreaks at higher wind speeds and lower standard operative temperatures (which combined temperature and wind speed). However, these cattle were kept in groups of four and could therefore give each other only little protection from wind. To warm each other with body heat emission and exhaled breath cattle have to come closer together, since warm air rises and mixes fast with surrounding cooler air. Cattle cannot give each other protection against precipitation and we therefore did not expect them crowding together during precipitation. It was surprising that our cows tended to frequent the forest and “Near protection, leeward” much less than the heifers. Still, they were able to find suitable microclimates, possibly due to more experience with weather and different habitat types and how much protection they offered. Beaver and Olson (1997) found that a herd of 7- to 8-year-old cattle used areas with higher standing crop significantly more than a 3-year-old cattle herd when grazing unprotected during winter time. The younger herd also used unprotected areas more frequently than the older herd, lost significantly more weight and tended to lose more backfat (Beaver and Olson, 1997). Their findings and ours can be arguments for keeping cattle in mixed age groups. Due to the higher average body weight (though equal approximate shoulder heights) the more experienced cows of this study must have had a bigger body volume than our less experienced heifers. Since body volume (where heat is produced) increases cubically but surface (where heat is released) quadratically, the cows must have had a smaller surface/volume ratio than the heifers (Eckert et al., 2000), i.e. there was less relative heat loss in the cows than in the heifers. The heifers were lying more than twice as often as the cows which may be explained by their need to temporarily reduce their surface/volume ratio. When lying, the surface where the animals can lose heat is reduced by the body surface touching other body surface (e.g. bent knees, legs touching the abdomen), whereas the volume nearly stays the same. Tucker et al. (2007) found that thinner cows were significantly more often lying with the forelegs bent and the hind legs touching the body than thicker cows which implies that thinner cows are in greater need to find protection as lying with the legs attached to the body is a way to save energy by minimizing surface/volume ratio. Moreover, by lying animals can also actively reduce the body surface exposed to wind. Additionally, as most cows in this study had a higher body condition score (4.5) than most heifers (4.0), they might have had better protection against cold than the heifers. Energy intake (which was not recorded)
may have differed between cows and heifers but the frequency of feeding and ruminating did not. 5. Conclusions Although the animals were unprotected most of the recordings they found microclimates with higher temperature and lower wind speed than at an open spot of the pasture. There were distinct changes in the cattle's behaviour due to Wind Chill Temperature and depending on the occurrence of rain or snow. Differences in behaviour due to experience were also found. Therefore, mixed age groups, where experienced cattle go with inexperienced cattle, might benefit the learning process of how to protect themselves from cold weather conditions. This can lead to faster physical adaptations and prevent cattle from losing body condition. Acknowledgements We would like to thank the animal owner Tomas Torsein for letting us use his animals and Kristina Lindgren from The Swedish Institute of Agricultural and Environmental Engineering for downloading the weather data. The Swedish Animal Welfare Agency (now Swedish Board of Agriculture) financed the study. References Arnold, G.W., Dudzinski, M.L., 1978. Ethology of free ranging domestic animals. Elsevier Sci. Publ. Co., Shers, Amsterdam. Baker, J.E., 2004. Effective environmental temperature. J. Swine Health Prod. 12, 140–143. Beaver, J.M., Olson, B.E., 1997. Winter range use by cattle of different ages in south-western Montana. Appl. Anim. Behav. Sci. 51, 1–13. Christopherson, R.J., 1985. Management and housing of animals in cold environments. In: Yousef, M.K. (Ed.), Stress Physiology in Livestock. Ungulates, II. CRC Press, Inc., Boca Raton, Florida, pp. 175–194. Eckert, R., Randall, D., Burggren, W., French, K., 2000. Tierphysiologie, 3rd ed. Georg Thieme Verlag, Stuttgart. Edmonson, A.J., Lean, I.J., Weaver, L.D., Farver, T., Webster, G., 1989. A body condition scoring chart for Holstein dairy cows. J. Dairy Sci. 72, 68–72. Environment Canada, 2003. Wind Chill Program. http://www.msc.ec.gc.ca/ education/windchill, last access March 25th 2010. Fox, D.G., Sniffen, C.J., O'Connor, J.D., 1988. Adjusting nutrient requirements of beef cattle for animal and environmental variations. J. Anim. Sci. 66, 1475–1495. Franck, D., 1979. Verhaltensbiologie: Einführung in die Ethologie. Georg Thieme Verlag, Stuttgart. Fraser, A.F., 1983. The behaviour of maintenance and the intensive husbandry of cattle, sheep and pigs. Agric. Ecosystems Environ. 9, 1–23. Gustafson, G.M., Lund-Magnussen, E., 1995. Effect of daily exercise on the getting up and lying down behaviour of tied dairy cows. Prev. Vet. Med. 25, 27–36. Hafez, E.S.E., Bouissou, M.F., 1975. The behaviour of cattle, In: Hafez, E.S.E. (Ed.), The Behaviour of Domestic Animals, 3rd ed. Baillière Tindall, London, pp. 203–245. Hall, S.J.G., 1989. Chillingham cattle: social and maintenance behaviour in an ungulate that breeds all year round. Anim. Behav. 38, 215–225. Hancock, J., 1950. Grazing habits of dairy cows in New Zealand. Emp. J. Exp. Agric. 18, 249–263. Hughes, G.P., Reid, D., 1951. Studies on the behaviour of cattle and sheep in relation to the utilization of grass. J. Agric. Sci. 41, 350–366 Cited in. Hafez, E.S.E. (Ed.), 1975. The Behaviour of Domestic Animals, 3rd ed. Baillière Tindall, London, p. 204. McDowell, R.E., Hooven, N.W., Camoens, J.K., 1976. Effect of climate on performance of Holsteins in first lactation. J. Dairy Sci. 59, 965–973. Mendl, M., Held, S., 2001. Living in groups: an evolutionary perspective. In: Keeling, L.J., Gonyou, H.W. (Eds.), Social Behaviour in Farm Animals. CABI Publishing, Oxon, pp. 7–36.
K.L. Graunke et al. / Livestock Science 136 (2011) 247–255 Olbrich, S.E., Martz, A., Hilderbrand, E.S., 1973. Ambient temperature and ration effects on nutritional and physiological parameters of heat and cold tolerant cattle. J. Anim. Sci. 37, 574–580. Olson, B.E., Wallander, R.T., 2002. Influence of winter weather and shelter on activity patterns of beef cows. Can. J. Anim. Sci. 82, 491–501. Phillips, C., 2002. Cattle Behaviour and Welfare, 2nd ed. Blackwell Science, Oxford. Redbo, I., Mossberg, I., Ehrlemark, A., Ståhl-Högberg, M., 1996. Keeping growing cattle outside during winter: behaviour, production and climatic demand. Anim. Sci. 62, 35–41. Saville, D.J., 1990. Multiple comparison procedures: the practical solution. Amer. Statistician 44, 174–180. Schütz, K.E., Clark, K.V., Cox, N.R., Matthews, L.R., Tucker, C.B., 2010. Responses to short-term exposure to simulated rain and wind by dairy cattle: time budgets, shelter use, body temperature and feed intake. Anim. Welf. 19, 375–383. Tucker, C.B., Rogers, A.R., Verkerk, G.A., Kendall, P.E., Webster, J.R., Matthews, L.R., 2007. Effects of shelter and body condition on the behaviour and physiology of dairy cattle in winter. Appl. Anim. Behav. Sci. 105, 1–13.
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Vandenheede, M., Nicks, B., Shehi, R., Canart, B., Dufrasne, I., Biston, R., Lecomte, P., 1995. Use of a shelter by grazing fattening bulls: effect of climatic factors. Anim. Sci. 60, 81–85. Wagner, D.G., 1988. Effects of cold stress on cattle performance and management factors to reduce cold stress and improve performance. Bovine Pract. 23, 88–93. Waßmuth, R., 2003. Winteraußenhaltung von Fleischrindern und Schafen. Dtsch. Tieraerztl. Wochenschr. 110, 212–215. Wassmuth, R., Wallbaum, F., Langholz, H.-J., 1999. Outdoor wintering of suckler cows in low mountain ranges. Livest. Prod. Sci. 61, 193–200. Webster, A.J.F., 1971. Prediction of heat losses from cattle exposed to cold outdoor environments. J. Appl. Physiol. 30, 684–690. Wechsler, B., Schaub, J., Friedli, K., Hauser, R., 2000. Behaviour and leg injuries in dairy cows kept in cubicle systems with straw bedding or soft lying mats. Appl. Anim. Behav. Sci. 69, 189–197. Young, B.A., 1975. Effects of winter acclimatization on resting metabolism of beef cows. Can. J. Anim. Sci. 55, 619–625. Young, B.A., Walker, B., Dixon, A.E., Walker, V.A., 1989. Physiological adaptation to the environment. J. Anim. Sci. 67, 2426–2432.
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Livestock Science j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / l i v s c i
Influence of weather on the behaviour of outdoor-wintered beef cattle in Scandinavia Katharina L. Graunke a,⁎, Tibor Schuster b,1, Lena M. Lidfors a,2 a b
Department of Animal Environment and Health, Swedish University of Agricultural Sciences, P.O. Box 234, SE-532 23 Skara, Sweden Institute of Medical Statistics and Epidemiology, Klinikum rechts der Isar der Technischen Universität München, Munich, Ismaninger Str. 22, 81675 München, Germany
a r t i c l e
i n f o
Article history: Received 13 October 2009 Received in revised form 17 September 2010 Accepted 18 September 2010 Keywords: Cattle Behavior Temperature Wind Outdoor Winter
a b s t r a c t The aim of the present investigation was to study the effect of weather and available protection on the behaviour of outdoor-wintered beef cattle (Bos taurus). A herd of 78–85 cattle head was studied during four winter months in the Southwest of Sweden. Protection was offered by coniferous forest situated on and around the 12 ha pasture, which we divided into protection categories. During 240 h we observed 10 cows and 10 heifers as focal animals (each 3 h/month) during day time and adjusted observation times to the altitude of the sun. Close to the animals and at an unprotected spot of the pasture we measured temperature, wind speed and solar radiation and combined these variables to a single measure called Wind Chill Temperature (WCT). During observations the animals were in the forest in 12.4%, near protection in 10.4% and without protection in 77.2% of the recordings. During precipitation, i.e. rain, snow and hail, the animals frequented the forest 2.71 times more often than during dry weather; however, only in 17.0% of the hours with precipitation the focal animals were in the forest. In 75.0% of the observation hours the WCT in the animals’ surrounding was at least 2 °C higher than at the most exposed spot of the pasture. Without precipitation the animals were lying less, feeding more and ruminating less at low WCT. During precipitation they were lying more, feeding less and ruminating more at low WCT. The lower the WCT and the higher the wind speed the more subjects there were within a 5 m-radius around the focal animal. The results indicate that the cattle adjusted their behaviour to both WCT and precipitation, that they were able to find warmer microclimates even without always having to frequent protecting objects, and that conspecifics were used as protection. © 2010 Elsevier B.V. All rights reserved.
1. Introduction A central factor for endothermic animals in coping with their environment is temperature which is especially important
⁎ Corresponding author. Present address: Leibniz Institute for Farm Animal Biology (FBN), Research Unit Behavioural Physiology, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany. Tel.: + 49 38208 68 823; fax: + 49 38208 68 802. E-mail addresses: [email protected] (K.L. Graunke), [email protected] (T. Schuster), [email protected] (L.M. Lidfors). 1 Tel.: + 49 89 4140 4324. 2 Tel.: + 46 511 67 215. 1871-1413/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2010.09.018
during winter. When temperature falls below the Lower Critical Temperature (LCT) animals must increase their metabolic heat production by shivering or other thermogenetic processes to keep up their body temperature (e.g. Christopherson, 1985; Eckert et al., 2000). At lower temperatures cattle have a greater need for energy (e.g. Fox et al., 1988; Young, 1975) and need to feed more (e.g. Fox et al., 1988; McDowell et al. 1976; Olbrich et al., 1973). The higher demand for energy may even result in weight loss (Christopherson, 1985; Webster, 1971). The LCT varies greatly depending on the stage of reproduction and physical conditions like coat length or fat layer (Christopherson, 1985). Investigations of the LCT usually have been determined on single-kept animals in restricted environments like stalls
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and climatic chambers (Christopherson, 1985). Therefore neither effects of a group nor wind, precipitation or radiation have been incorporated in the LCT (Christopherson, 1985). The temperature animals experience is the Effective Environmental Temperature which is influenced by environmental factors that include heat loss by conduction, radiation and convection (Baker, 2004). Increasing wind speed decreases the experienced temperature whereas solar radiation increases it (Environment Canada, 2003). Precipitation, primarily rain, reduces the insulation capacity of a coat (Young et al., 1989) and furthermore cools the insulating air layer within the coat by evaporation (Eckert et al., 2000). Cattle have a very strict diurnal behaviour pattern. Being crepuscular animals grazing peaks occur around sunrise and sunset whereas there is low activity at midday (Arnold and Dudzinski, 1978; Fraser, 1983; Hafez and Bouissou, 1975). Therefore grazing in cattle is adjusted to sunlight (Hughes and Reid, 1951) which plays a very important role for the daily pattern especially in the northern countries where the day length and intensity of solar radiation are much less in winter than in summer. Other behaviours are influenced by the grazing pattern (Hafez and Bouissou, 1975) so that possibly the time with a low activity level during midday might decrease in length or even disappear during very short winter days. The ability to learn allows animals to behaviourally adjust to their particular environment (Franck, 1979). Beaver and Olson (1997) found that experienced beef cows grazed more
frequently in areas that were protected from weather than inexperienced cows. Waßmuth (2003) therefore suggests that heifers should be raised outdoors and that cows have to be brought to their winter pasture early enough to acclimate to the (weather) conditions. Little is known about the type of protection cattle choose when performing different behaviours and if that choice is dependent on weather. The aim of this study was to investigate the effect of temperature, wind speed, solar radiation and precipitation on behaviour and the use of natural protection of outdoorwintered cattle (Bos taurus) with varying experience. We predicted that cattle would prefer to rest well protected from wind and precipitation, that they would feed and ruminate more in cold weather, and that they would lie more in warm sunny and cold snowy weather. Furthermore we expected that more experienced cattle would seek protection more effectively and react faster to weather changes. 2. Materials and methods 2.1. Materials The study was carried out in the Southwest of Sweden (58°19′ N, 13°29′ E) on a slightly hilly pasture of 12 ha (130 m above sea level) with 10 m altitude difference. Coniferous forest covered about 1/3 of the pasture and deciduous and coniferous forest surrounded it at three sides (Fig. 1). The
Fig. 1. Map of the study field with available protection; the permanent green marks forest the animals could go into. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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studied herd consisted of 78–85 adult beef cattle head of different breeds and their crossbreeds and up to 50 calves. The cattle were fed grass silage mostly at noon three times per week. They had ad libitum access to the silage from three movable feedracks. Protocol and conduct of this study were approved by the Ethical Committee on Animal Experiments, Gothenburg.
Table 1 Definition of the recorded body positions and behaviours of beef cattle kept outdoors during winter time. Parameters Body position Standing Walking Running Lying Behaviour Feeding
2.2. Methods Ten cows (5–10 years) and 10 heifers (3 years) of Black Angus–Charolais-crossbreed or Black Angus were randomly selected. The herd had experienced at least two winters in the area and was used to the weather conditions at these latitudes. The focal cows weighed 625 kg (SD ± 34 kg) on average throughout the winter whereas the heifers weighed 561 kg (SD ± 61 kg). The most frequent body condition score in the focal animals was 4.0 (as was the mean) at measurements at the start, the middle and the end of the experiment (1.0:= “severe under-conditioning” to 5.0:= “severe overconditioning”, after Edmonson et al., 1989). At each measurement half of the cows had a body condition score of 4.5 whereas the most frequent body condition score in the heifers was 4.0 (six heifers at the start and middle measurement and four at the end, 4.0:= “frame not as visible as covering”). At the beginning of the observations all focal animals except for three heifers were pregnant. After one month of observations a non-pregnant heifer had to be replaced with a pregnant substitute heifer due to injury. We divided the pasture into the protection categories: “In forest”, “Near protection” and “No protection”. Groves, stone walls, bushes, solitary trees and forest could offer protection. Depending on size and height a distance of 5–10 m to the protecting object was allowed to be called “Near protection”. According to wind direction the category “Near protection” was classified as “leeward” or “windward” during observations. See Fig. 1 for available protection. Observations were made during 15 days/month from December 2006 to March 2007 by the same trained observer who observed in total 240 h. Every focal animal was observed in total 12 h, 3 h/month and 1 h/observation, which means that behavioural recordings on each individual were repeated three times per month. The repetitions within each month were carried out at different times and days after a randomly made time table. Each day observations were made 2 h in the morning and 2 h in the afternoon; one cow and one heifer each were observed every morning and every afternoon. Feeding usually took place in between morning and afternoon observations. Observation times were adjusted to the altitude of the sun. Morning observations began 15 min after sunrise and afternoon observations 70 min after solar noon to cover most of the daily activity. The number of animals in a two-cow-lengths-radius (ca. 5 m) around the focal animal's head was recorded. We assumed that the more individuals there were within the radius, the shorter the distance was between the animals in the group. Body position and behaviour (Table 1), protection category and animals in the two-cow-lengths-radius were recorded instantaneously at 4-min intervals. Some behaviours can be performed in different body positions. In this study, the term
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Ruminating No activity Other
Definition At least 3 legs touch ground, no forward movement Max. 3 legs touch ground, forward movement Max. 2 legs touch ground, fast forward movement Body touches ground, no weight on legs Picking, chewing or swallowing silage or vegetation or sucking and swallowing water Regurgitating or chewing on partly digested food No visible activity, no vigilance or exploring All other behaviour not named above
“behaviour” included all possible body positions within this behaviour and with the term “body position”, all possible behaviours were included, if not stated otherwise. For part of the analyses we summarised the behaviours ruminating and no activity to a new parameter called “resting” which can be performed both standing and lying. Directly after each behavioural recording at 4-min intervals temperature, wind speed and solar radiation were measured with a portable weather station (PWS) (LM-8000, Lutron Electronic Enterprise Co., Taiwan) at 1.1 m above the ground within the two-cow-lengths-radius of the focal animal and precipitation (rain, snow, hail) was noted. A stationary weather station (SWS) (WXT 510, Vaisala, Finland) was placed at an open spot of the pasture without protection from weather (Fig. 1). Both weather stations were tested for similarity in their measurements in the field. Due to the availability of data from the weather stations, the number of observation hours with weather data ranges between 205 and 238. For statistical analyses weather data was combined to a single measure called Wind Chill Temperature (WCT) given in °C for each weather station. An equation developed by Environment Canada (2003) and modified by Tucker et al. (2007) was used:
W
13.12+ 0.6215 × Tair − 13.17 × V 0.16 + 0.3965 × Tair × V 0.16 wind chill index based on °C
Tair
air temperature in °C
V
wind speed in km/h
W
When the wind speed is 0.72 km/h or below this equation would add some units to the temperature and hence in this case the original temperature was used as wind chill index W. According to Environment Canada (2003) bright sunshine might reduce the effect of wind chill by 6–10°. The observer noted that a bright cloudless winter day in the pasture's latitude never had a light intensity below 20 000 lx and a sunny day with some clouds never had a light intensity below 15 000 lx. Light intensity of the stationary weather station was measured in kW/m² which is not convertible into lux. Thus values in lux taken from the portable weather station next to the stationary weather station were compared with measures from the stationary weather station in kW/m² taken at the same time. 15 000 lx corresponded roughly with
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0.1 kW/m² and 20 000 lx with 0.2 kW/m². Therefore the following modifications were done for this study: IF V ≤ 0.72 km/h THEN W = Tair IF solar radiation ≥ 15 000 lx (PWS) OR 0.1 kW/m² (SWS) THEN WCT = W + 6 IF solar radiation ≥ 20 000 lx (PWS) OR 0.2 kW/m² (SWS) THEN WCT = W + 10 Otherwise WCT = W 2.3. Statistics For statistical analyses all measures were combined per observation hour except for the percentage of lying and resting standing in different protection categories which was calculated per animal. A mean value per hour was calculated of the temperature, wind speed, WCT and of the number of animals in the two-cow-lengths-radius of the focal animal. Protection categories were given codes which became higher the less protection the category offered (1:= “In forest”, 2:= “Near protection, leeward”, 3:= “Near protection, windward”, 4:= “No protection”). The median value of the code was calculated per observation hour which gave information of what protection category the animals stayed in the most. The number of recordings of each body position and behaviour were summed per hour. An observation hour was declared as “with precipitation” when at least one precipitation event occurred, since wet or snow-covered ground might influence the animals’ behaviour. Statistical analyses were done with SPSS 15.0 (SPSS Inc., USA) and R version 2.5.1 (The R Foundation for Statistical Computing, Austria). To evaluate differences in the use of the four protection categories we summarized the number of observations in the different protection categories per animal (only those who were observed all four months, n = 19) and conducted the Friedman two-way analysis of variance by ranks (df = 3). Pairwise differences between protection categories as well as differences in weather data from the two stations (number of observation hours: 205 for WCT and temperature, 206 for wind speed) were tested with the Wilcoxon signed ranks test (two-tailed). To estimate the influence of different factors on the response variables we used Generalized Linear Mixed Models (GLMM) to consider time-dependent autocorrelation of repeated observations within the same animal. For count data a Poisson-regression model-link was used and logistic regression model-link functions for multinomial data with the reference category “No protection”. Tested explanatory variables were WCT and wind speed of PWS and SWS, precipitation, age group and month. GLMM regression coefficients (transformed by the exponential function: ecoefficient) give an estimate for the mean relative change (denoted as “factor”) of outcome measure by a one-unit increment of the corresponding explanatory variable or category and are provided with 95% confidence intervals (CI). Factor “1.00” means there is no effect on the response (e.g. the number of feeding events per hour) by the appropriate variable (e.g. the WCT). A factor smaller than 1.00 means the response becomes smaller by the factor per unit (e.g. per 1 m/s) or category (e.g. per protection category), a factor bigger than 1.00 makes the response bigger by the
factor per unit or category. Confidence intervals excluding factor 1.00 depict a statistically significant relationship of response and explanatory variable. All statistical tests were performed two-tailed and a p-value b 0.05 was considered to indicate statistical significance. To retain a maximum of power and to avoid overconservatism in the primary interesting analyses, no correction for multiple testing (increment of false positive results with the number of statistical tests being conducted) was performed. However, according to Saville (1990) an informal adjustment for multiple comparisons may be conducted by the reader based on the results (particularly the number of statistical tests) which are thoroughly provided in the text. 3. Results 3.1. Weather and its general impact on behaviour February was the coldest month and March was the warmest month (Table 2). The difference of WCT between morning and afternoon was largest in March (7.3 °C) when days became longer and the sun's zenith higher and was smallest in December (1.4 °C) when days were shortest and the sun's zenith lowest. The animals were standing in 79.8% of the recordings, lying in 13.4%, walking in 6.7% and running in 0.1%. They were lying 6.0 percentage points more in the morning than in the afternoon. Differences during the day were largest in February when the cattle were lying 29.3% of the recordings in the morning whereas only 3.6% in the afternoon. They then walked more than twice as much during afternoons (8.2%) compared to mornings (4.0%). The animals were feeding in 35.6%, ruminating in 27.0%, showing no activity in 19.5% and showing other behaviour in 17.9% of the recordings. The mean WCT was higher in the surrounding of the focal animal (PWS) than at the stationary weather station (SWS) in 90.2% of the observation hours (P b 0.001). In 95.6% of the observation hours temperature was higher (P b 0.001) and in all hours wind speed was lower around the focal animal than at the SWS (P b 0.001). Compared to the stationary weather station mean values at the portable weather station were 1.8 °C higher for temperature and 3.7 °C for WCT and 1.7 m/s lower for wind speed (Table 3). In 19 of 205 hours the WCT at the SWS was higher than in the focal animals’ surrounding (PWS) and in 17 of these 19 hours the cattle were at spots of the pasture where solar radiation was lower than at the exposed spot where the SWS was situated (e.g. in the forest). In 2 of the 19 hours there was partly drizzle at average temperatures of 5.6 °C and 5.0 °C.
Table 2 Mean ± SD of Wind Chill Temperature (WCT) in °C, temperature in °C and wind speed in m/s at the stationary weather station during the four observation months.
December January February March
WCT
Temperature
Wind speed
−2.7 ± 3.4 −5.1 ± 4.8 −7.6 ± 6.3 2.3 ± 5.6
1.4 ± 4.3 0.2 ± 4.3 −3.3 ± 4.0 4.0 ± 3.0
2.4 ± 1.9 3.3 ± 2.1 2.5 ± 1.5 3.0 ± 1.5
K.L. Graunke et al. / Livestock Science 136 (2011) 247–255 Table 3 Mean ± SD, minimum and maximum of temperature and Wind Chill Temperature (WCT) in °C (number of observation hours: 205) and of wind speed in m/s (number of observation hours: 206) for portable (PWS) and stationary weather station (SWS) calculated from means per observation hour during four winter months. Mean ± SD
Temperature WCT Wind speed
Minimum
Maximum
PWS
SWS
PWS
SWS
PWS
SWS
2.3 ± 5.0 0.4 ± 5.9 1.2 ± 1.0
0.5 ± 4.8 −3.3 ± 6.6 2.9 ± 1.8
−11.6 −16.9 0.0
−12.5 −22.7 0.4
13.8 21.0 6.6
11.3 16.6 9.4
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P = 0.018). There was a tendency to use the category “Near protection, windward” 3.52 times more often during precipitation (factor: 3.52, CI: 0.95–13.02, P = 0.060). Precipitation did not significantly influence the use of the category “Near protection, leeward”. WCT had no significant impact on the use of the protection categories. 3.4. Impacts on body position and behaviour
Lying differed significantly among the protection categories (P b 0.001), but there was no significant difference in the recorded number of lying behaviours between “No protection” and “In forest” (Fig. 2). The animals were hardly lying “Near protection” (Fig. 2). When the proportion of lying per category was compared it was significantly higher “In forest” (41.2%, P = 0.002) than in ”No protection” (8.6%). Resting (ruminating and no activity while standing or lying) differed significantly among the protection categories (P b 0.001, Fig. 2). The animals rested unprotected in significantly more recordings than in the forest (P b 0.001, Fig. 2). The cows and heifers were in 12.4% of the recordings in the forest, in 5.9% “Near protection, leeward”, in 4.5% “Near protection, windward” and in 77.2% unprotected (Fig. 2). When resting in the forest, the animals were lying in 54.8% of the recordings, whereas when resting unprotected the percentage of lying was only 21.3% (Fig. 2).
Decreasing WCT influenced lying, feeding and ruminating differently depending on if there was no precipitation or if there was precipitation. The higher the WCT the more the animals were lying when there was no precipitation (factor: 1.19/°C, CI: 1.14–1.25, P b 0.001, Fig. 3a). When there was precipitation the animals were lying the more the lower the WCT was (factor: 0.90/°C, CI: 0.87–0.93, P b 0.001, Fig. 3a). In total the animals were lying nearly ¼ less during precipitation than when no precipitation (factor: 0.76, CI: 0.61–0.94, P = 0.012). The lower the WCT the more the animals were feeding when there was no precipitation (factor: 0.92/°C, CI: 0.89–0.95, P b 0.001, Fig. 3b). When there was precipitation the animals were feeding the more the higher the WCT was (factor: 1.05/°C, 1.03–1.08, P b 0.001, Fig. 3b). In total the animals were feeding ¼ less during precipitation than when no precipitation (factor: 0.75, CI: 0.65–0.86, P b 0.001). The higher the WCT the more the animals were ruminating when there was no precipitation (factor: 1.07/°C, CI: 1.03–1.10, P b 0.001, Fig. 3c). When there was precipitation the animals were ruminating the more the lower the WCT was (factor: 0.96/°C, CI: 0.94–0.98, P b 0.001, Fig. 3c). In total the animals tended to ruminate more during precipitation than when no precipitation (factor: 1.12, CI: 0.98–1.29, P = 0.095).
3.3. Use of protection
3.5. Conspecifics as protection
In 36.7% of the observation hours there was at least one interval with precipitation. In 17.0% of those hours the focal animal was mainly in the forest. The forest was used 2.71 times more often when there was precipitation than when there was no precipitation (factor: 2.71, CI: 1.19–6.20,
The lower the WCT the more animals there were in the radius of the focal animal (factor: 0.98/°C, CI: 0.97–0.99, P b 0.001, Fig. 4). With every successive observation month the number of animals in the radius of the focal animal decreased with more than ¼ (factor: 0.74/month, CI: 0.64– 0.84, P b 0.001). The higher the wind speed the more animals there were in the focal animal's radius (factor: 1.08/m/s, CI: 1.03–1.14, P = 0.002, Fig. 4). When unprotected the cows and heifers had almost 1.45 times as many animals in their radius than in the forest (factor: 1.13/protection category, CI: 1.05– 1.23, P = 0.002). Precipitation had no significant impact on the number of cattle in the focal animals’ radius.
3.2. Choice of resting spots standing and lying
100 90 80
Percentage
70 60 50
3.6. The role of experience
40 30 20 10 0 Total
In forest
Not resting
Near Near No protection, protection, protection leeward windward Resting standing Lying
Fig. 2. Percentage of recordings of not resting, resting standing and lying in total and in the different protection categories of outdoor-wintered beef cattle (n = 19).
Heifers tended to be in the forest 2.33 times more often than cows (factor: 0.43, CI: 0.18–1.01, P = 0.053) and tended to use the category “Near protection, leeward” 3.45 times more often than cows (factor: 0.29, CI: 0.07–1.19, P = 0.085). The difference between WCT of PWS and SWS showed no differences between the cows and heifers in median and quartiles (Fig. 5), merely the upper whisker and the distribution of outliers were different. In 75.0% of the observation hours the cattle were in microclimates where WCT was at least 2 °C warmer than where the SWS was placed regardless of protection category.
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Wind speed portable weather station in m/s
No. of animals in the 5 m-radius of the focal animals
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WCT portable weather station in °C Fig. 4. Estimated mean number (with 95% confidence bands) of other cattle in the radius of the focal animals at different Wind Chill Temperatures (WCT) (grey filled plane with solid boundaries) and different wind speeds (blank plane with dotted boundaries) of the portable weather station calculated on base of the Poisson-regression model. The axes cover the range of minimum and maximum of the variables (number of observation hours: 238).
Heifers were lying 2.22 times more often than cows (factor: 0.45, CI: 0.21–0.95, P = 0.037), but ruminating and feeding did not significantly differ between cows and heifers. The number of animals in the radius of the focal animals did not significantly differ between cows and heifers.
4. Discussion The animals in this study were standing a large (79.8%) and lying a small proportion (13.4%) of the observations which were made during daylight. This is similar to what has been found in the free living Chillingham cattle in northern England which were standing 71.4% and lying 14.9% during daylight (Hall, 1989). Walking played a much bigger role in the Chillingham cows (13.1% (Hall, 1989) vs. 6.8% in this study), most probably because the study included summer when the cattle were grazing whereas in this study the animals had ad libitum access to silage during observations and were in no need of searching for pasture. The big difference in the apportionment of body positions between morning and afternoon in February may result from the cold Fig. 3. Estimated mean number (with 95% confidence bands) of recordings per observation hour of a) lying, b) feeding and c) ruminating of beef cattle kept outdoors during winter at different Wind Chill Temperatures (WCT) of the portable weather station during precipitation (solid lines, grey filled planes) and without precipitation (dashed lines, blank planes), calculated on base of the Poisson-regression model. The axes cover the range of minimum and maximum of the variables (number of observation hours: 238 for lying and ruminating; 205 for feeding).
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12
Difference of WCT between portable and stationary weather station in °C
11 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 Heifers
Cows
Fig. 5. Difference of the Wind Chill Temperature (WCT) between the stationary and portable weather station in °C shown for heifers and cows (medians, 5th, 25th, 75th and 95th percentiles, *: outliers; number of observation hours: 205).
mornings (mean temperature −4.1 °C, SD ± 3.9 °C, mean WCT −9.8 °C, SD ± 5.7 °C) and could be interpreted as a reaction to cold as Redbo et al. (1996) found that outdoorwintered dairy steers were lying more during cold days. Redbo et al. (1996) also associated increasing temperature with increasing movement which is in accordance with our observations of high percentages of walking in February afternoon when it was warmer than in the mornings. The cows and heifers in this study were in areas with a higher WCT than at the SWS during more than 90% of the observations. This was often due to the wind speed being lower where the cows and heifers were, compared to the open area where the SWS was placed. However, 14 of the 20 focal cows and heifers were observed to be in areas which had lower WCT than at the SWS during one or two observation hours. Thus, the cattle were obviously in no need to find warmer microclimates during those hours. The WCT in these hours never came close to −13 °C which has been reported to be the LCT in beef cows in early pregnancy (Christopherson, 1985). On these occasions the animals were often standing in the forest where light intensity was lower than in the open field which changed the WCT. In this study the cattle were rather standing than lying when resting unprotected. One reason for this may be their inability to flee or scare off predators instantly when lying, as the standing up-process takes several seconds (Gustafson and Lund-Magnussen, 1995; Wechsler et al., 2000). Without protection animals are easier spotted and reached than in the forest. Resting includes sleep (lying) and a half-asleep dozing state (lying and standing) which cattle often reach while ruminating (Phillips, 2002). In those states they perceive their environment subdued and possible danger
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might not be noticed right away. From inside the forest (10 m and more from the edge) the outside-surrounding is quite easily observed, whereas from the outside details in the darker inside can hardly be seen. Animals inside the forest therefore have additional time to react before they are spotted which is especially important while lying. This could be the reason for why the animals were more often standing than lying when resting without protection. The animals in this study were seeking protection more often when there was precipitation, although they were unprotected during 83.0% when this occurred. However, precipitation was slightly overstated since an hour was classified as “with precipitation” as soon as it occurred once, no matter of duration and intensity. If duration and especially intensity were regarded, results might have been different, yet this was not possible in this study. Vandenheede et al. (1995) reported a significantly higher occupation rate of a human-built shelter without bedding by fattening beef bulls from 0.4 mm rain per hour and from at least 2 h duration. They mentioned that rain with lower intensity or shorter duration could be pleasant for cattle. However, their study was made during the summer with 14.1 °C mean temperature. Shorter less intense rain at lower temperatures may have the same effect on the animals as longer more intense rain at higher temperatures, whereas snow might have a quite different influence; Wagner (1988) drew similar conclusions. Snow at lower temperatures is rather dry and animals might not be as affected as by rain. The study by Vandenheede et al. (1995) did not regard wind speed which is an important factor in thermal stress particularly in combination with rain (Christopherson, 1985). The finding in the presented study that the animals were lying less during precipitation regardless of the WCT and more at lower WCT while precipitation shows that the cattle tried to lie less when it was wet on the ground. Wassmuth et al. (1999) observed similar behaviour. Schütz et al. (2010) found that rain decreased the duration of lying in dairy cattle kept at a mean temperature of 10 °C. When cattle were feeding often as a consequence ruminating occurred little and vice versa. Therefore feeding and ruminating were opposite to each other. At lower temperatures animals have a greater need for energy (e.g. Fox et al., 1988; Young, 1975) and need to feed more (e.g. Fox et al., 1988; McDowell et al., 1976; Olbrich et al., 1973). Another explanation for our observation of more feeding at lower WCT is day length. Higher WCT occurred mainly during March when the median day length was 680 min (December–February median day length 456 min). As cattle mostly feed during daylight and twilight (e.g. Arnold and Dudzinski, 1978; Hafez and Bouissou, 1975; Hancock, 1950) they had about 4 h more time to feed in March when WCT was quite high. Then they had time for a midday rest as described by Fraser (1983) and Hafez and Bouissou (1975). During December and January observations not only began with daybreak (like in February and March) but also ended with dusk and therefore covered most of the daylight period except for 90–120 min around noon. Feeding was probably mainly compressed into the short day and longer breaks could not be afforded. An estimated higher number of recordings of feeding was the result and therefore rumination had to be opposed. Food was only provided in the category “No protection”. During precipitation the categories
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“In forest” and “Near protection, windward” were frequented with a higher probability when compared to “No protection”. As a result the animals were more likely to ruminate than to feed during precipitation. There were more animals in the radius of the focal animals in this study the higher the wind speed, the lower the WCT and when they were unprotected. Mammals living in groups often huddle together to conserve warmth (Mendl and Held, 2001). In the forest the subjects could not crowd together as easily as outside and it might not have been as important, since trees protect from wind and precipitation. Bodies break the wind and can by that protect from it; therefore having more animals around gave the individual protection from wind. Olson and Wallander (2002) found that cattle spent more time behind windbreaks at higher wind speeds and lower standard operative temperatures (which combined temperature and wind speed). However, these cattle were kept in groups of four and could therefore give each other only little protection from wind. To warm each other with body heat emission and exhaled breath cattle have to come closer together, since warm air rises and mixes fast with surrounding cooler air. Cattle cannot give each other protection against precipitation and we therefore did not expect them crowding together during precipitation. It was surprising that our cows tended to frequent the forest and “Near protection, leeward” much less than the heifers. Still, they were able to find suitable microclimates, possibly due to more experience with weather and different habitat types and how much protection they offered. Beaver and Olson (1997) found that a herd of 7- to 8-year-old cattle used areas with higher standing crop significantly more than a 3-year-old cattle herd when grazing unprotected during winter time. The younger herd also used unprotected areas more frequently than the older herd, lost significantly more weight and tended to lose more backfat (Beaver and Olson, 1997). Their findings and ours can be arguments for keeping cattle in mixed age groups. Due to the higher average body weight (though equal approximate shoulder heights) the more experienced cows of this study must have had a bigger body volume than our less experienced heifers. Since body volume (where heat is produced) increases cubically but surface (where heat is released) quadratically, the cows must have had a smaller surface/volume ratio than the heifers (Eckert et al., 2000), i.e. there was less relative heat loss in the cows than in the heifers. The heifers were lying more than twice as often as the cows which may be explained by their need to temporarily reduce their surface/volume ratio. When lying, the surface where the animals can lose heat is reduced by the body surface touching other body surface (e.g. bent knees, legs touching the abdomen), whereas the volume nearly stays the same. Tucker et al. (2007) found that thinner cows were significantly more often lying with the forelegs bent and the hind legs touching the body than thicker cows which implies that thinner cows are in greater need to find protection as lying with the legs attached to the body is a way to save energy by minimizing surface/volume ratio. Moreover, by lying animals can also actively reduce the body surface exposed to wind. Additionally, as most cows in this study had a higher body condition score (4.5) than most heifers (4.0), they might have had better protection against cold than the heifers. Energy intake (which was not recorded)
may have differed between cows and heifers but the frequency of feeding and ruminating did not. 5. Conclusions Although the animals were unprotected most of the recordings they found microclimates with higher temperature and lower wind speed than at an open spot of the pasture. There were distinct changes in the cattle's behaviour due to Wind Chill Temperature and depending on the occurrence of rain or snow. Differences in behaviour due to experience were also found. Therefore, mixed age groups, where experienced cattle go with inexperienced cattle, might benefit the learning process of how to protect themselves from cold weather conditions. This can lead to faster physical adaptations and prevent cattle from losing body condition. Acknowledgements We would like to thank the animal owner Tomas Torsein for letting us use his animals and Kristina Lindgren from The Swedish Institute of Agricultural and Environmental Engineering for downloading the weather data. The Swedish Animal Welfare Agency (now Swedish Board of Agriculture) financed the study. References Arnold, G.W., Dudzinski, M.L., 1978. Ethology of free ranging domestic animals. Elsevier Sci. Publ. Co., Shers, Amsterdam. Baker, J.E., 2004. Effective environmental temperature. J. Swine Health Prod. 12, 140–143. Beaver, J.M., Olson, B.E., 1997. Winter range use by cattle of different ages in south-western Montana. Appl. Anim. Behav. Sci. 51, 1–13. Christopherson, R.J., 1985. Management and housing of animals in cold environments. In: Yousef, M.K. (Ed.), Stress Physiology in Livestock. Ungulates, II. CRC Press, Inc., Boca Raton, Florida, pp. 175–194. Eckert, R., Randall, D., Burggren, W., French, K., 2000. Tierphysiologie, 3rd ed. Georg Thieme Verlag, Stuttgart. Edmonson, A.J., Lean, I.J., Weaver, L.D., Farver, T., Webster, G., 1989. A body condition scoring chart for Holstein dairy cows. J. Dairy Sci. 72, 68–72. Environment Canada, 2003. Wind Chill Program. http://www.msc.ec.gc.ca/ education/windchill, last access March 25th 2010. Fox, D.G., Sniffen, C.J., O'Connor, J.D., 1988. Adjusting nutrient requirements of beef cattle for animal and environmental variations. J. Anim. Sci. 66, 1475–1495. Franck, D., 1979. Verhaltensbiologie: Einführung in die Ethologie. Georg Thieme Verlag, Stuttgart. Fraser, A.F., 1983. The behaviour of maintenance and the intensive husbandry of cattle, sheep and pigs. Agric. Ecosystems Environ. 9, 1–23. Gustafson, G.M., Lund-Magnussen, E., 1995. Effect of daily exercise on the getting up and lying down behaviour of tied dairy cows. Prev. Vet. Med. 25, 27–36. Hafez, E.S.E., Bouissou, M.F., 1975. The behaviour of cattle, In: Hafez, E.S.E. (Ed.), The Behaviour of Domestic Animals, 3rd ed. Baillière Tindall, London, pp. 203–245. Hall, S.J.G., 1989. Chillingham cattle: social and maintenance behaviour in an ungulate that breeds all year round. Anim. Behav. 38, 215–225. Hancock, J., 1950. Grazing habits of dairy cows in New Zealand. Emp. J. Exp. Agric. 18, 249–263. Hughes, G.P., Reid, D., 1951. Studies on the behaviour of cattle and sheep in relation to the utilization of grass. J. Agric. Sci. 41, 350–366 Cited in. Hafez, E.S.E. (Ed.), 1975. The Behaviour of Domestic Animals, 3rd ed. Baillière Tindall, London, p. 204. McDowell, R.E., Hooven, N.W., Camoens, J.K., 1976. Effect of climate on performance of Holsteins in first lactation. J. Dairy Sci. 59, 965–973. Mendl, M., Held, S., 2001. Living in groups: an evolutionary perspective. In: Keeling, L.J., Gonyou, H.W. (Eds.), Social Behaviour in Farm Animals. CABI Publishing, Oxon, pp. 7–36.
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