Impact of forage inclusion rate on the occurrence and persistence of feed sorting behaviour in growing dairy cattle

开发了一种新的生长奶牛饲养方案，在干式全混合日粮(TMR)中使用切碎的秸秆和多种质地的小牛精料，目的是提供一致的谷物和饲料摄入量，包括用于瘤胃刺激的磨料纤维的良好来源，以及足够的精料摄入量，以提供所需的营养。这项饲喂计划的主要特点之一是保持饲料和谷物在配方数量上的一致摄入量。对口粮的饮食选择(分类)有可能导致营养摄入量不平衡。因此，本研究的目的是确定饲料含量水平对饲喂这种干式TMR计划的年轻奶牛的分选行为和生长的影响。第二个目标是确定在小牛犊转换为常规日粮后，发展起来的喂养模式是如何延续的。我们假设，提高饲料内含物水平将增加谷物的分选量，从而增加营养消耗的可变性。我们还假设，这种行为将在小牛犊转变为常规日粮后继续存在。为了验证这些假设，10头荷斯坦犊牛从出生到12周龄，将被分配到两个处理中的一个：1)85%精料和15%碎秸秆，持续12周；或者2)85%精料和15%碎秸秆，持续6周，然后是70%精料和30%碎秸秆，持续6周。在24周龄时，所有动物将过渡到常规日粮，包括50%玉米青贮料和50%干草料，为期3周。在整个研究过程中，将监测饲料摄入量、行为(分拣、喂食、躺卧和反胃)、生长和健康。这项研究不仅将为Nutreco Canada AgResearch的这一饲养计划提供经验支持，而且还将补充Guelph大学的研究，以创造关于奶牛饲养行为发展的基础知识。这项研究的主要受益者是加拿大乳制品生产商，他们实施这一饲养计划，以降低饲料成本，并改善他们的替代奶牛的健康、效率和福利。

A new feeding program for growing dairy cattle, which incorporates chopped straw and a multi-textured calf concentrate in a dry total mixed ration (TMR), has been developed with the intent of providing consistent intakes of grain and forage, including a good source of abrasive fibre for rumen stimulation, and sufficient intake of concentrate to provide nutrients required. One of the key features of this feeding program is to maintain a consistent intake of both forage and grain in the formulated amounts. Dietary selection (sorting) of the ration has the potential to cause imbalances in nutrient intakes. Thus, the objective of this research is to determine the impact of forage inclusion level on the sorting behaviour and growth of young dairy cattle fed this dry TMR program. A secondary objective is to determine how developed feeding patterns carry over after the calves are switched to a conventional ration. We hypothesize that increasing the forage inclusion level will increase the amount of sorting for grain, thus increasing variability in nutrients consumed. We also hypothesize that this behaviour will carry over after calves are transitioned to a conventional ration. To test these hypotheses, 10 Holstein calves, raised similarly from birth to 12 weeks of age, will be assigned 1 of 2 treatments: 1) 85% concentrate and 15% chopped (2.5 cm) straw for 12 weeks; or 2) 85% concentrate and 15% chopped straw for 6 weeks, then 70% concentrate and 30% chopped straw for 6 weeks. At 24 weeks of age, all animals will be transitioned to a conventional ration, containing 50% corn silage and 50% haylage, for a 3-week period. Feed intake, behaviour (sorting, feeding, lying, and ruminating), growth, and health will be monitored throughout the study. This research will not only provide Nutreco Canada Agresearch empirical support for this feeding program, but also complement research at the University of Guelph in creating fundamental knowledge on the development of feeding behaviour in dairy cattle. The primary beneficiaries of this research are the Canadian dairy producers who implement this feeding program to reduce feed costs, and improve the health, efficiency, and welfare of their replacement dairy cattle.