Grazing behaviour and feeding preferences in pastured dairy cows and heifers

放牧奶牛和小母牛的放牧行为和喂养偏好

• 批准号: RGPIN-2014-06353
• 负责人: Bergeron, Renée
• 金额: $ 1.89万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612177
• 关键词: Grazing; behaviour; feeding; preferences; pastured

Pasturing is the most natural and welfare friendly way to feed dairy animals, and is a requirement in organic dairying. When given the choice, cows prefer to be on pasture rather than inside in the summer, and their ability to select their own diet is thought to promote their welfare. Achieving high levels of animal performance and health from grazed forage is a key objective within most pasture-based, milk production systems. Over the next five years, I will continue to study dairy cows in pasture-based production systems, with the intent of improving their efficiency, through better cow productivity and health. The long-term goal of this program is to advance our understanding of feeding preference and grazing behaviour of cows in a pasture-based production system. This goal will be achieved by a series of short-term objectives, which aim to determine how feeding preferences and grazing behaviour: 1) are related to health and productivity; 2) can be modified by early experience and learning; 3) are related to forage characteristics. A first experiment will be designed to relate individual differences in feeding preference and grazing behaviour with health and productivity. We predict that cows that fare better on pasture are more efficient grazers and select for optimal energy and protein intake and/or beneficial plants. In a second experiment, we will determine if heifer preference for a bioactive forage, in this case a forage rich in secondary metabolites that are active against parasites is affected by their parasitic load. We predict that heifers with the highest parasitic load will preferentially select forage rich in secondary compounds, and that preference will become more pronounced over time, with the increase in parasitic load. In a third experiment, the development of grazing behaviour and possible long-term benefits of an early introduction to pasture will be studied. We hypothesize that a sensitive period for the acquisition of grazing skills exists, and that heifers learning during this period will become better grazers later in life. In a fourth experiment, the effect of pasturing animals with more experienced ones will be evaluated. We predict that group housing during the milk feeding stage and the presence of an older animal at pasture will help calves learn to graze more efficiently. In a fifth experiment, calves will be exposed to a selection of fresh plant species at the various stages of ruminant digestion, in an attempt to detect a sensitive period for learning of plant characteristics. We hypothesize that heifers learning during the sensitive period will show a preference for these plants later in life. In experiments 6, we will study preferences of dairy cows on experimental pastures containing small plots of various plant species. We predict that cows will show a clear preference for legume species, but that preferences will vary with time of day and stage of maturity of the experimental forages. In experiment 7, preferences of cows for freshly cut plant species will be studied and related to the physicochemical characteristics of the plants. We hypothesize that cow preference or aversion for forage species will be predicted by their physicochemical characteristics such as fibre content, soluble carbohydrates, and secondary compounds. A better knowledge of cow preferences on pasture will help determine optimal pasture composition and pasture management practices to maintain cow performance and health. Understanding the link between grazing behaviour and cow performance will help in our genetic selection of cows that are better adapted to pasture-based systems. Finally, understanding learning mechanisms involved in grazing behaviour will help with the training of cows to become more efficient grazers.

放牧是最自然和福利友好的方式来喂养奶牛，是有机乳制品的要求。如果可以选择，奶牛在夏天更喜欢在牧场上而不是在室内，它们选择自己饮食的能力被认为能促进它们的福利。在大多数以牧场为基础的牛奶生产系统中，实现高水平的动物生产性能和健康是一个关键目标。在接下来的五年里，我将继续研究牧场生产系统中的奶牛，目的是通过提高奶牛的生产力和健康来提高它们的效率。这个项目的长期目标是促进我们对放牧生产系统中奶牛的喂养偏好和放牧行为的理解。这一目标将通过一系列短期目标来实现，这些目标旨在确定喂养偏好和放牧行为：1)与健康和生产力的关系；2)可以通过早期的经验和学习进行修改；3)与牧草特性有关。第一个实验将被设计成将个体在饲养偏好和放牧行为上的差异与健康和生产力联系起来。我们预测，在牧场上表现更好的奶牛是更有效的食草动物，它们会选择最佳的能量和蛋白质摄入量和/或有益的植物。在第二个实验中，我们将确定小母牛对生物活性饲料的偏好是否受到其寄生负荷的影响，在这种情况下，富含抗寄生虫次生代谢物的饲料。我们预测，寄生负荷最高的小母牛会优先选择富含次生化合物的饲料，而且随着时间的推移，这种偏好会随着寄生负荷的增加而变得更加明显。在第三个实验中，将研究放牧行为的发展和早期引入牧场可能带来的长期利益。我们假设存在一个获得放牧技能的敏感期，并且在此期间学习的小母牛将在以后的生活中成为更好的食草者。在第四个实验中，将评估与更有经验的动物一起放牧的效果。我们预测，在哺乳阶段的群体住房和牧场上有一只老动物的存在将帮助小牛更有效地学习放牧。在第五个实验中，小牛将在反刍动物消化的不同阶段暴露于精选的新鲜植物物种中，试图检测植物特征学习的敏感期。我们假设在敏感期学习的小母牛会在以后的生活中表现出对这些植物的偏好。在实验6中，我们将研究奶牛对小块种植各种植物的实验牧场的偏好。我们预测，奶牛将表现出对豆科植物的明显偏好，但这种偏好将随着一天中的时间和实验饲料的成熟阶段而变化。在实验7中，将研究奶牛对新割植物的偏好，并将其与植物的理化特性联系起来。我们假设奶牛对饲料品种的偏好或厌恶将由它们的物理化学特征（如纤维含量、可溶性碳水化合物和次生化合物）来预测。更好地了解奶牛对牧场的偏好将有助于确定最佳牧场组成和牧场管理措施，以保持奶牛的生产性能和健康。了解放牧行为和奶牛表现之间的联系将有助于我们对奶牛进行基因选择，使其更好地适应以牧场为基础的系统。最后，了解放牧行为的学习机制将有助于训练奶牛成为更高效的食草动物。