Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC V6T 1Z6, Canada.
Biol Lett. 2023 Jan;19(1):20220475. doi: 10.1098/rsbl.2022.0475. Epub 2023 Jan 18.
Hunger remains a significant animal welfare concern as restricted feeding practices are common on farms. Studies to date have focused on negative effects on health and productivity but little research has addressed the , mostly due to methodological difficulties in assessing animals' subjective experiences. Here, we explored the use of a cognitive approach to disentangle motivational hunger (a normal state that is of limited welfare concern) from distressful hunger (a state associated with intense negative emotions). Cognitive performance in a foraging task is expected to follow an inverted U relationship with hunger levels, providing an opportunity to make inferences about different hunger states. We assessed the effect of milk restriction on calf cognition in two experiments using a modified hole-board test. Experiment 1 showed that reducing milk allowance from 12 to 6 l d impaired all measures of cognitive performance. Experiment 2 showed that the same type of feed restriction also disrupted calves' capacity to re-learn. We conclude that hunger associated with reduced milk allowance can disrupt cognitive performance of dairy calves, a result consistent with the experience of distressful hunger.
饥饿仍然是一个重要的动物福利问题，因为限制喂养在农场中很常见。迄今为止的研究主要集中在对健康和生产力的负面影响上，但很少有研究涉及到这一点，主要是因为评估动物主观体验的方法存在困难。在这里，我们探讨了使用认知方法来区分正常状态下的动机性饥饿（这种饥饿对福利的关注有限）和与强烈负面情绪相关的痛苦性饥饿（这种饥饿是一种状态）。在觅食任务中的认知表现预计会随着饥饿水平呈倒 U 型关系，这为推断不同的饥饿状态提供了机会。我们使用改良的洞板测试在两项实验中评估了牛奶限制对小牛认知的影响。实验 1 表明，将牛奶供应量从 12 升/天减少到 6 升/天会损害所有认知表现的衡量标准。实验 2 表明，同样类型的饲料限制也会破坏小牛重新学习的能力。我们的结论是，与牛奶供应减少相关的饥饿会干扰奶牛小牛的认知表现，这与痛苦性饥饿的体验一致。
