Jensen Margit Bak, Larsen Lars Erik
Department of Animal Science, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark.
National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, DK-1870 Frederiksberg C, Denmark.
J Dairy Sci. 2014;97(8):5035-44. doi: 10.3168/jds.2013-7311. Epub 2014 May 23.
Housing preweaned dairy calves in pairs rather than individually has been found to positively affect behavioral responses in novel social and environmental situations, but concerns have been raised that close contact among very young animals may impair their health. In previous studies, the level of social contact permitted in individual housing has been auditory, visual, or physical contact. It is unclear how these various levels of social contact compare with each other and to pair housing, when their effects on behavior and health are considered, and whether the timing of pair housing has an effect. To investigate this, 110 Holstein calves (50 males, 60 females) in 11 blocks were paired according to birth date. Within 60h of birth, each pair of calves was allocated to 1 of 5 treatments: individual housing with auditory contact (I), individual housing with auditory and visual contact (V), individual housing with auditory, visual, and tactile contact (T), pair housing (P), or individual housing with auditory and visual contact the first 2wk followed by pair housing (VP). At 6wk of age, calves were subjected to a social test and a novel environment test. In the social test, all pair-housed calves (P and VP) had a shorter latency to sniff an unfamiliar calf than did individually housed calves (I, V, and T), whereas calves with physical contact (T, P, and VP) sniffed the unfamiliar calf for longer than calves on the remaining treatments (I and V). In the novel environment test, calves with physical contact (T, P, and VP) had a lower heart rate, and more of these calves vocalized during the test compared with calves without physical contact (I and V). No effect of treatment was found for clinical scores, levels of the 5 most common pathogens in feces, or in development of serum antibodies against the 3 most common respiratory pathogens. Calves housed individually are more fearful of unfamiliar calves than are pair-housed calves. Contrary to common belief, the allowance of physical contact and pair housing had no effects on the health of the calves.
研究发现，将断奶前的犊牛成对饲养而非单独饲养，在新的社交和环境情境中会对其行为反应产生积极影响，但有人担心幼小动物之间的密切接触可能会损害它们的健康。在之前的研究中，个体饲养中允许的社交接触水平包括听觉、视觉或身体接触。当考虑到它们对行为和健康的影响时，尚不清楚这些不同水平的社交接触彼此之间以及与成对饲养相比如何，也不清楚成对饲养的时间是否有影响。为了对此进行研究，将11个组块中的110头荷斯坦犊牛（50头雄性，60头雌性）按出生日期配对。在出生后60小时内，每对犊牛被分配到5种处理方式中的一种：有听觉接触的个体饲养（I）、有听觉和视觉接触的个体饲养（V）、有听觉、视觉和触觉接触的个体饲养（T）、成对饲养（P），或在前两周有听觉和视觉接触然后成对饲养的个体饲养（VP）。在6周龄时，对犊牛进行社交测试和新环境测试。在社交测试中，所有成对饲养的犊牛（P和VP）嗅闻陌生犊牛的潜伏期都比单独饲养的犊牛（I、V和T）短，而有身体接触的犊牛（T、P和VP）嗅闻陌生犊牛的时间比其他处理方式（I和V）下的犊牛长。在新环境测试中，有身体接触的犊牛（T、P和VP）心率较低，与没有身体接触的犊牛（I和V）相比，更多这类犊牛在测试过程中发出叫声。在临床评分、粪便中5种最常见病原体的水平或针对3种最常见呼吸道病原体血清抗体的产生方面，未发现处理方式有影响。单独饲养的犊牛比成对饲养的犊牛更害怕陌生犊牛。与普遍看法相反，允许身体接触和成对对犊牛的健康没有影响。
