Abstract Calves reared on pasture learn to graze from their dam and conspecifics during weaning. Social learning can be beneficial for calf performance and welfare, and pair-housing and companionship on pasture have been proposed as management practices to develop efficient foraging behaviour. Yet, the interaction between early housing and the experience of a companion on the development of grazing and ruminating behaviour is unknown. The objective of this experiment was to investigate the effect of early housing and experience of a companion on heifer behaviour during their first grazing season. The experiment was designed as a two by two factorial with six replicates per factorial combination repeated over two seasons. In each season, 12 focal heifers were single- or pair-housed before the experiment began. At the start of each trial season, the focal heifers were placed on pasture for the first time and paired with an unknown companion heifer of similar bodyweight and age. Half of the focal heifers were paired with a naive grazer companion and the other half with an experienced grazer companion. The experiment started when the newly formed pairs of heifers were placed on pasture (day 0). Posture and behaviour (grazing, ruminating and others) were recorded during the morning and afternoon for both heifers using scan sampling every two minutes for six hours per day on days 1, 2, 3, 10 and 17 after pasture placement. Data were analyzed separately for focal and companion heifers, using generalized linear mixed models, with pen nested in the model as the experimental unit and days on pasture as a repeated measure. The early housing and the experience of a companion had a synergistic effect over time on the percentage of time that focal heifers were ruminating (early-housing: P = 0.048; and companion experience: P = 0.049) but not grazing (early-housing: P = 0.40; and companion experience: P = 0.27). Pair-housed heifers placed on pasture with experienced heifers were ruminating more (14.1 ± 1.5%) than single-housed heifers with naive heifers (9.8 ± 1.5%; P = 0.02). Over the duration of the experiment, the patterns of grazing and rumination behaviour during the morning and afternoon were similar between focal and companion heifers. These results suggest that early socialization and grazing with an experienced companion (i.e. social model) influence ruminating behaviour on pasture in first grazing season heifers, probably due to social facilitation.

中文翻译：

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早期饲养和同伴经验对幼小母牛在牧场上放牧和反刍行为的影响

摘要 在牧场上饲养的犊牛在断奶期间学会从母牛和同种动物中吃草。社会学习对犊牛的表现和福利有益，并且已经提出配对饲养和牧场陪伴作为发展有效觅食行为的管理实践。然而，早期住房与同伴在放牧和反刍行为发展方面的经验之间的相互作用尚不清楚。该实验的目的是调查早期饲养和同伴经历对小母牛在第一个放牧季节的行为的影响。该实验被设计为一个二乘二的因子，每个因子组合在两个季节重复六个重复。在每个季节，12 头焦点小母牛在实验开始前单独或成对饲养。在每个试炼季开始时，焦点小母牛首次被放置在牧场上，并与体重和年龄相似的未知伴侣小母牛配对。一半的焦点小母牛与幼稚的食草动物伴侣配对，另一半与经验丰富的食草动物伴侣配对。当新形成的小母牛对被放置在牧场上时（第 0 天），实验开始。在放牧后的第 1、2、3、10 和 17 天，每天 6 小时，每两分钟进行一次扫描采样，记录两只小母牛的姿势和行为（放牧、反刍和其他）。使用广义线性混合模型分别分析焦点和伴生小母牛的数据，以模型中嵌套的笔作为实验单元，在牧场上的天数作为重复测量。随着时间的推移，早期饲养和同伴的经验对焦点小母牛反刍（早期饲养：P = 0.048；同伴体验：P = 0.049）但不放牧（早期饲养： P = 0.40；同伴体验：P = 0.27）。与经验丰富的小母牛放在牧场上的成对饲养的小母牛比使用幼小母牛的单户小母牛反刍更多 (14.1 ± 1.5%) (9.8 ± 1.5%; P = 0.02)。在整个实验期间，焦点小母牛和伴侣小母牛在上午和下午的放牧和反刍行为模式相似。这些结果表明，早期社会化和与经验丰富的同伴（即社会模式）一起放牧会影响第一放牧季节小母牛在牧场上的反刍行为，这可能是由于社会促进。