USDA-ARS, US Dairy Forage Research Center, Marshfield, WI 54449.
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 2018 Sep;101(9):7930-7941. doi: 10.3168/jds.2018-14543. Epub 2018 Jun 13.
Various forms of overcrowding are common in heifer-rearing operations. Our objectives for this study were to evaluate the effects of overstocking at the feedbunk (100, 133, 160, or 200% of capacity) on the growth performance, feedbunk sorting behaviors, and hygiene of 128 gravid Holstein heifers (475 ± 55.3 kg) consuming an alfalfa haylage and corn silage diet diluted with processed wheat straw at an inclusion rate of 25.2% (DM basis). In this study, heifers were overstocked only at the feedbunk, and not with respect to available freestalls or pen area. Heifers were blocked by weight, and subsequently assigned to 1 of 16 identical research pens. A total mixed ration was distributed at 1000 h daily for 91 d via a drive-through feed alley, with heifers allowed access to the feedbunk through head-locking feeding gates. Mean weights for the 4 blocks (32 heifers/block) were 406 ± 14.9, 453 ± 15.3, 493 ± 17.6, and 548 ± 21.9 kg. Generally, nutrient intakes were not affected by stocking rate at the feedbunk; mean intakes of dry matter, neutral detergent fiber, and total digestible nutrients across all feedbunk stocking rates were 10.63, 5.19, and 6.29 kg/d, respectively. Overall, the effects of competition at the feedbunk on heifer growth performance were minor, with a collective average daily gain of 1.02 kg/d across all treatments. Only trends for linear increases in total weight gain and BCS were observed with overstocking at the feedbunk. Collectively, overstocked rates also exhibited a trend for better feed-to-gain ratio than pens stocked at 100% of feedbunk capacity (10.3 vs. 11.0 kg:kg). We observed solid evidence that heifers collectively sorted against large (>19 mm) particles, and also exhibited preference for short (>1.18 and <8 mm) and fine (<1.18 mm) feed particles; however, these responses were not affected by feedbunk stocking rate. Additionally, heifers sorted against neutral detergent fiber as the concentration of neutral detergent fiber remaining in the feedbunk increased during the 24-h period following feeding; conversely, they preferred crude protein, as indicated by a decreasing concentration of this nutrient over time. Heifer hygiene was not affected by competition at the feedbunk. Under the experimental conditions established for this trial, overstocking at the feedbunk did not affect heifer growth performance, but it should not be practiced blindly without attention to other critical components of animal welfare.
在育肥牛饲养操作中，各种形式的过度拥挤是很常见的。我们这项研究的目的是评估在饲料槽中过度饲养（100%、133%、160%或 200%的容量）对 128 头怀孕荷斯坦奶牛（475±55.3kg）生长性能、饲料槽分类行为和卫生的影响，这些奶牛食用苜蓿干草和玉米青贮饲料日粮，并用加工过的小麦秸秆以 25.2%（DM 基础）的比例进行稀释。在这项研究中，仅在饲料槽过度饲养奶牛，而不是根据可用的自由站立式畜栏或畜栏面积进行过度饲养。奶牛按体重分组，然后分配到 16 个相同的研究畜栏之一。通过一条直通式饲料通道，每天 10:00 分配全混合日粮，通过头锁式进料门让奶牛进入饲料槽。4 个块（32 头奶牛/块）的平均体重分别为 406±14.9kg、453±15.3kg、493±17.6kg 和 548±21.9kg。一般来说，饲养率对饲料槽的养分摄入量没有影响；所有饲料槽饲养率下，干物质、中性洗涤剂纤维和总可消化养分的平均摄入量分别为 10.63kg/d、5.19kg/d 和 6.29kg/d。总的来说，饲料槽竞争对育肥牛生长性能的影响较小，所有处理的平均日增重为 1.02kg/d。仅观察到随着饲料槽过度饲养，总增重和体况评分呈线性增加的趋势。总的来说，过度饲养的比例也表现出比饲养率为 100%的饲料槽更好的饲料增重比（10.3 比 11.0kg：kg）。我们有确凿的证据表明，奶牛集体排斥大（>19mm）颗粒，并且还表现出对短（>1.18 和<8mm）和细（<1.18mm）饲料颗粒的偏好；然而，这些反应不受饲料槽饲养率的影响。此外，随着中性洗涤剂纤维在喂食后 24 小时内留在饲料槽中的浓度增加，奶牛会排斥中性洗涤剂纤维；相反，随着时间的推移，它们会偏好粗蛋白，因为这种营养素的浓度会下降。饲料槽竞争对奶牛的卫生状况没有影响。在本试验设定的实验条件下，饲料槽过度饲养并不影响育肥牛的生长性能，但如果不注意动物福利的其他关键因素，不应盲目实施。
