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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567752
• 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动物，是有机乳品业的要求。当给予选择时，奶牛更喜欢在牧场上而不是在夏天，他们选择自己饮食的能力被认为是促进他们的福利。从放牧饲料中获得高水平的动物性能和健康是大多数以牧场为基础的牛奶生产系统的关键目标。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状况来提高奶牛的效率。该计划的长期目标是促进我们对牧场生产系统中奶牛的饲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，这些目标旨在确定摄食偏好和放牧行为如何：1）与健康和生产力有关; 2）可以通过早期经验和学习加以改变; 3）与饲料特性有关。第一个实验将被设计为与健康和生产力的摄食偏好和放牧行为的个体差异。我们预测，在牧场上表现更好的奶牛是更有效的食草动物，并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，在这种情况下，富含对寄生虫有活性的次级代谢产物的饲料是否受到其寄生虫负荷的影响。我们预测，具有最高寄生负载的小母牛将优先选择富含次级化合物的饲料，并且随着时间的推移，随着寄生负载的增加，偏好将变得更加明显。在第三个试验中，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，存在一个敏感时期的收购放牧技能，小母牛在此期间学习将成为更好的食草动物以后的生活。在第四个实验中，将评估用更有经验的动物放牧动物的效果。我们预测，在牛奶喂养阶段的群体住房和存在的一个老动物在牧场将帮助小牛学会更有效地吃草。在第五个实验中，小牛将在反刍动物消化的各个阶段接触选择的新鲜植物物种，试图检测学习植物特征的敏感期。我们假设，小母牛在敏感期学习将显示出对这些植物的偏好在以后的生活。在实验6中，我们将研究奶牛对包含各种植物物种的小块试验牧场的偏好。我们预测，奶牛将表现出明显的偏好豆类物种，但偏好将随时间的一天和成熟的实验牧草的阶段。在实验7中，将研究奶牛对新鲜切割植物物种的偏好，并将其与植物的理化特性相关联。我们假设，奶牛的偏好或厌恶饲料品种将预测其理化特性，如纤维含量，可溶性碳水化合物，和二级化合物。更好地了解奶牛对牧场的偏好将有助于确定最佳的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性能之间的联系将有助于我们从基因上选择更适应牧场系统的奶牛。最后，了解放牧行为中的学习机制将有助于训练奶牛成为更有效的放牧者。