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Rapport2007Öppen tillgång

Behaviour and use of protection in heifers and suckler cows kept outside in the winter time in Sweden

Graunke, Katharina

Sammanfattning

In today’s agricultural environment it is possible for free-ranging cattle to behave almost as natural as they would in the wild. Usually free-ranging cattle live in mixed age groups and the cows and heifers mate naturally with breeding bulls which temporarily stay with the herd. Besides feeding of mineral supplements feeding only happens during winter time and concentrates are seldom fed. The animals are able to cope with different environmental challenges like low temperature, high wind speed or precipitation up to a certain degree by adapting physically and changing their behaviour. This means that cattle are capable of living outdoors even during winter without physical suffering, if certain conditions like access to food, possibilities of protection or good body condition and health are fulfilled. Little is known about the correlation between weather and the use of natural or artificial protection by cattle in Northern Europe and the results of the few carried out studies and observations of the animal owners are very diverse. Age and experience with winter weather and pregnancy play a role as well as outdoor raising of young cattle which makes early physical adaptation possible and which lets them learn protection behaviour as young animals. There is little knowledge about the influence of weather on the cattle’s behaviour in semi-natural environments. The aim of this study was to investigate the behaviour of cattle (Bos taurus) kept in seminatural environment during winter time and to study the effect of weather, available protection and experience on the behaviour. The study was carried out in the southwest of Sweden on the farm Trestena on a pasture of 12 ha which had not been used for agriculture for at least eight years. Protection was available by coniferous forest which was situated both on and around the pasture dividing it into four protection categories: In forest; Near protection, wind abandoned side; Near protection, wind facing side; No protection. From December 4th 2006 till March 22nd 2007 ten cows and ten heifers of Black Angus and Black Angus-Charolais-crossbreeds were ob-served as focal animals during a total of 240 hours. Each animal was followed one hour at a time and recordings were made with instantaneous sampling at 4-minute intervals for body position and general behaviour and continuously for social behaviour. Four hours of observations were carried out each day and these observation times were adjusted to the position of the sun. Temperature, wind speed and solar radiation were measured both in the animals’ surrounding every four minutes and at the most exposed spot of the pasture per hour and later per 15 minutes. The different variables were combined to a single measure called Wind Chill Temperature (WCT). All collected data was analysed with a Poissonregression model-link, logistic regression model-link functions, the Friedman two-way analysis of variance by ranks, the Wilcoxon signed ranks test and the Sign test. To get an overview of the behaviour of the cows and heifers the percentages of the different body positions and the general and social behaviours were shown separately for morning and afternoon. The animals were lying more in the mornings than in the afternoons. The cows and heifers were feeding more in the afternoons, probably because feeding took place at noon from the end of January on. However, in December the cows and heifers spent more time feeding in the afternoon as well, even though feeding took place in the late afternoon. Social behaviours were of aggressive nature for about ¾ of the social recordings. Aggressive social behaviours were shown 21.9 percentage points more often while feeding from the feedracks and silage bales on the ground than while not feeding. During the four months of observations the cows and heifers were in the forest in 12.4 %, near protection in 10.4 % and without protection in 77.2 % of the recordings. In total, there were no significant differences in the number of recordings when the cows and heifers were lying without protection compared to lying in the forest. If the proportionate percentages of lying per protection category were compared, the cows and heifers were lying significantly more in the forest compared with lying without any protection (p < 0.001). Resting (lying, ruminating, showing no activity) was quite similar, still the frequency of resting in the forest was significantly smaller if compared with resting without any protection (p < 0.001). The comparison of the proportionate percentages of resting in the forest compared with no protection showed significant differences (p < 0.01). During precipitation, i.e. rain, snow and hail, the cows and heifers frequented the forest 2.71 times more often than when there was no precipitation (p < 0.05). No significant influence on the use of protection was established for the WCT alone. However, in 75 % 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. The mean temperature differed with 1.8 °C (p < 0.001) and the mean wind speed differed with 1.7 m/sec (p < 0.001) between those areas. The general behaviours lying, feeding and ruminating were all influenced by WCT, precipitation and precipitation at different WCT. Without precipitation the cows and heifers were lying less (p < 0.001), feeding more (p < 0.001) and ruminating less (p < 0.001) at low WCT. During precipitation they behaved the other way around and were lying more (p < 0.001), feeding less (p < 0.001) and ruminating more (p < 0.001) at low WCT. Social behaviours were influenced by WCT, precipitation and precipitation at different WCT as well. When there was no precipitation, social behaviours in total (p < 0.001) and aggressive behaviours (p < 0.001) were less likely to be shown when the WCT was high, whereas during precipitation the probability to show social behaviours in total (p < 0.001) and aggressive behaviours (p < 0,001) was bigger when the WCT was low. The number of other cattle within a two-cow-lengths-ambit around the focal animal was influenced by WCT and wind speed but not significantly by precipitation. At lower WCT (p < 0.001) and higher wind speeds (p < 0.01) there were more animals around the focal animal than at higher WCT and lower wind speeds. Furthermore, in the forest the cows and heifers had less other animals close to them than without any protection (p < 0.01). The heifers and cows had found similar microclimates, but to do so the heifers tended to frequent the forest more than twice as often as the cows (p = 0.053). In total the heifers were also lying more than twice as often as the cows (p < 0.05). The rare observations of direct behavioural changes due to weather show the difficulties to measure those changes. Still, they point out the importance that experienced cattle can have for the protection behaviour of a herd. Keeping animals in mixed age groups and giving some individuals the chance to evolve life experience and the capability to influence the behaviour of a whole herd is essential if the animals are kept outdoors at least for some time of the year. The results indicate that the animals adapted to the circumstances and behaved differently according to the weather and degree of protection. The cows and heifers were able to find warmer microclimates even without always having to frequent protecting objects. The circumstances around feeding seem to hold a considerable stress potential especially at lower temperatures. However, to have conspecifics for protection during cold temperatures and high wind speeds seems to be important for cattle both when no other protection is available and when there is other protection. Experience seems to play a central role for cattle in the way of protecting themselves from weather and the ability to find suitable microclimates. The results indicate that the heifers did not have the same skills to find similar microclimates outside the forest as the cows. Further research on this topic has to be done in order to learn more about the relations between different factors of beef production with free-ranging cattle

Publicerad i

Rapport (Sveriges lantbruksuniversitet, Institutionen för husdjurens miljö och hälsa)
2007, nummer: 18
Utgivare: Department of Animal Environment and Health, Swedish University of Agricultural Sciences