Department of Sustainable Agricultural Systems, University of Natural Resources and Life Sciences, 1180, Vienna, Austria.
Recipient of a DOC-Fellowship of the Austrian Academy of Sciences, Vienna, Austria.
Sci Rep. 2020 Dec 10;10(1):21699. doi: 10.1038/s41598-020-78748-7.
Play is a strong outwardly directed, emotional behaviour and can contagiously spread between individuals. It has been suggested that high-playing animals could 'seed' play in others, spreading positive affective states. Despite the current interest in play contagion there has been no previous attempt to measure the strength of the play contagion effect. The calf (Bos taurus) is ideal for testing the strength of play contagion as play in calves is strongly related to energy intake from milk. We manipulated play in calves through their milk allowances and housed the calves in uniform groups all on the same milk allowance (high = UHigh or low = ULow) or in mixed groups with calves in the same group receiving either a high (= MHigh) or low (= MLow) milk allowance. We measured locomotor play using accelerometers on two consecutive days when calves were four and eight weeks old, in order to study play contagion over a protracted developmental window. We anticipated that differences in the level of play contagion between treatment groups would result in difference in the play levels observed in the MLow and ULow individuals. Contrary to our expectations we found that spontaneous play was suppressed in the high-milk calves housed in mixed groups (MHigh), in comparison to calves housed with group mates all receiving high-milk (UHigh). These results are the first to quantify a negative play contagion effect, particularly in a situation of long-term contact, and may suggest that negative contagion has a stronger effect on play behaviour than positive contagion.
玩耍是一种强烈的外向性行为，能够在个体之间传播。有人认为，高玩耍动物可以“播种”玩耍，传播积极的情感状态。尽管目前人们对玩耍的感染力很感兴趣，但之前没有人试图衡量玩耍感染力的强度。小牛（Bos taurus）是测试玩耍感染力的理想选择，因为小牛的玩耍与从牛奶中获得的能量摄入密切相关。我们通过牛奶供应量来控制小牛的玩耍，并将它们安置在相同的小组中，所有小组的牛奶供应量都相同（高=UHigh 或低=ULow）或混合小组中，同一组的小牛接受高（=MHigh）或低（=MLow）的牛奶供应量。我们使用加速度计在小牛 4 周和 8 周大时连续两天测量运动性玩耍，以研究在一个长时间的发育窗口中玩耍的感染力。我们预计，治疗组之间玩耍感染力的差异会导致 MLow 和 ULow 个体观察到的玩耍水平的差异。与我们的预期相反，我们发现，与与所有接受高牛奶的同组小牛（UHigh）相比，混合组中高牛奶喂养的小牛（MHigh）的自发性玩耍受到抑制。这些结果是首次量化负面玩耍感染力的影响，特别是在长期接触的情况下，这可能表明负面感染力对玩耍行为的影响比积极感染力更强。
