Trouw Nutrition R&D, PO Box 299, 3800 AG, Amersfoort, the Netherlands.
Trouw Nutrition R&D, PO Box 299, 3800 AG, Amersfoort, the Netherlands; Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
J Dairy Sci. 2020 May;103(5):4275-4287. doi: 10.3168/jds.2019-17382. Epub 2020 Feb 26.
The recent trend in the dairy industry toward ad libitum feeding of young calves merits reconsideration of calf milk replacer (CMR) formulations. Additionally, feed intake regulation in young calves provided with ad libitum milk and solid feeds is insufficiently understood. This study was designed to determine the effect of exchanging lactose for fat in CMR on voluntary feed intake and growth performance. Lactose was exchanged for fat on a weight/weight basis, resulting in different energy contents per kilogram of CMR. Thirty-two male calves (1.7 ± 0.12 d of age, 47.6 ± 0.83 kg of body weight) were assigned to 1 of 16 blocks based on arrival date. Within each block, calves were randomly assigned to 1 of 2 treatments. The experimental period was divided into 4 periods. In period 1, until 14 ± 1.7 d of age, calves were individually housed, restricted-fed their assigned CMR treatments at 2.5 to 3 L twice daily, and provided with unlimited access to water, chopped straw, and starter. In period 2, calves were group-housed with 8 calves per pen and received ad libitum access to their assigned CMR treatments, starter feed, chopped wheat straw, and water. During period 3, from 43 until 63 d of age, calves were weaned by restricting CMR allowance in 2 steps, maintaining access to all other feeds. All calves were completely weaned at d 64 of age and were monitored until 77 d of age (period 4). Measurements included the intake of all dietary components, body weight gain, and a selection of blood traits. Increasing fat content at the expense of lactose decreased CMR intake by 10%, whereas total calculated metabolizable energy intake and growth remained equal between treatments. Total solid feed (starter and straw) consumption was not affected by CMR composition. These data indicate that calves fed ad libitum regulate their CMR intake based on energy content. High-fat CMR increased plasma phosphate, nonesterified fatty acids, triglycerides, and bilirubin, whereas plasma glucose remained unchanged. Despite the limited animal numbers in the present experiment, there was a significant decrease in the total number of health events (mainly respiratory) requiring therapeutic intervention and in the total number of therapeutic interventions in calves fed high-fat CMR. Calves appeared to consume CMR based on energy content, with a difference in ad libitum intake proportional to the difference in energy content of the CMR, maintaining equal body weight gain and solid feed intake.
最近，乳制品行业的一个趋势是让小牛自由采食，这使得人们有必要重新考虑小牛代乳粉（CMR）的配方。此外，对于提供自由采食牛奶和固体饲料的小牛，其采食量的调节机制还不够清楚。本研究旨在确定用脂肪替代 CMR 中的乳糖对自由采食和生长性能的影响。用脂肪替代乳糖，按照重量/重量的比例，导致每公斤 CMR 的能量含量不同。32 头雄性小牛（1.7 ± 0.12 日龄，47.6 ± 0.83 公斤体重）根据到达日期分为 16 个块的 16 个块之一。在每个块内，小牛随机分配到 2 种处理中的 1 种。实验期分为 4 个阶段。在第 1 阶段，直到 14 ± 1.7 日龄，小牛被单独饲养，每天两次以 2.5 至 3 升的量限制喂养他们分配的 CMR 处理，并提供无限量的水、切碎的稻草和起始饲料。在第 2 阶段，小牛被分组饲养，每栏 8 头小牛，自由采食他们分配的 CMR 处理、起始饲料、切碎的小麦秸秆和水。在第 3 阶段，从 43 日龄到 63 日龄，通过两步限制 CMR 供应来使小牛断奶，同时保持所有其他饲料的供应。所有小牛在 64 日龄完全断奶，并在 77 日龄（第 4 阶段）进行监测。测量包括所有饮食成分的摄入量、体重增加和一系列血液特征。以牺牲乳糖为代价增加脂肪含量会使 CMR 摄入量减少 10%，而总计算可代谢能量摄入和生长在处理之间保持相等。CMR 组成不影响总固体饲料（起始饲料和稻草）的消耗。这些数据表明，自由采食的小牛根据能量含量调节 CMR 摄入量。高脂肪 CMR 增加了血浆磷酸盐、非酯化脂肪酸、甘油三酯和胆红素，而血糖保持不变。尽管本实验动物数量有限，但需要治疗干预的健康事件（主要是呼吸道）总数和高脂肪 CMR 喂养的小牛的治疗干预总数均显著减少。小牛似乎根据能量含量消耗 CMR，自由采食量的差异与 CMR 的能量含量差异成正比，同时保持相等的体重增加和固体饲料摄入量。
