Effects of mother versus artificial rearing during the first 12 weeks of life on challenge responses of dairy cows.

@enWe investigated the effects of mother versus artificial rearing on the responses to a social and a non-social challenge in adulthood. Rearing of treatment groups only differed during the first 12 weeks of life. Artificially reared animals were separated from their mothers within 24 h after birth and fed via an automatic milk feeder six times (A6, n=6) or twice (A2, n =5) a day. They were housed together with calves suckled by their mothers twice a day for 15 min (M2, n =9) or with permanent access to the cow barn and thus to their mothers and the cow herd via selection gates (MP, n = 6). After weaning animals of all rearing treatments were kept together until integration into the dairy cow herd. About 4.5 months after calving (age 31 +/- 1.4 months), cows were subjected to an isolation test and two novel objects tests (first: traffic cone, second: ball). ANOVA (behaviour: heart rate of novel object tests) and GLMM (heart rate and cortisol responses to isolation) were used for statistical analyses. During isolation, MP cows were more active: they walked significantly longer (P=0.036), tended to enter more squares in the middle area of the test arena (P=0.059), and to explore the arena or the outer environment for longer (P=0.056) than cows of the other three treatments. In addition, MP and A6 cows had the lowest mean heart rate during isolation, whereas after return into the herd the MP cows showed the lowest heart rate. Cortisol levels differed between groups dependent on sampling time (P=0.001), with MP cows having the lowest basal values but the highest after the isolation test. In the novel object tests, A6 cows tended to explore the traffic cone later (P=0.051), focused the ball earlier (P =0.040) and tended to use the area farther away from the ball more often than cows of the other three treatments (P=0.100). These results in 2.5-year-old cows suggest that rearing with permanent access to the mother and the herd increases sociality leading to higher behavioural activity during isolation and affects physiological stress reactions so that they resemble a reactive coping style, while reaction to novel objects in the home environment is not affected by mother rearing. (C) 2015 Published by Elsevier B.V.

• Effect of the early social environment on welfare and later challenge responses of dairy cattle.

Johann Heinrich von Thünen Institute
Johannes Kepler Universität Linz
Veterinärmedizinische Universität Wien