Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5.
Dairy Technology Research Institute, Feed-Livestock and Guidance Department, The National Federation of Dairy Co-operative Associations (ZEN-RAKU-REN), Nishi-shirakawa, Fukushima, Japan 969-0223.
J Dairy Sci. 2020 May;103(5):4423-4434. doi: 10.3168/jds.2019-17676. Epub 2020 Feb 26.
This study investigated how providing hay mixed with calf starter to dairy calves affected their solid feed intake, feed sorting, growth, and plasma metabolite and hormone concentrations. Forty Holstein heifer calves were fed a texturized calf starter (23.4% crude protein, 32.3% starch on a dry matter basis) and chopped Klein grass hay as separate components (CONT) or the same starter and hay mixed at a 90:10 ratio on an as-fed basis (MIX) ad libitum from the date transported to the research farm (4-7 d of life) to 90 d of life. Calves were provided milk replacer (28% crude protein, 15% fat) at up to 557 g/d before the study, 737 g/d from d 14 to 20, 1,105 g/d from d 21 to 41, 737 g/d from d 42 to 48, and 557 g/d from d 49 to 55 on a dry matter basis. calves were fully weaned on d 56. Feed sorting for the MIX calves was evaluated using the Penn State Particle Separator; the sorting index was calculated as the actual intake as a percentage of predicted intake, with values >100% indicating sorting for and values <100% indicating sorting against. Treatment did not affect solid feed intake, growth performance, or plasma metabolite or hormone concentration during the preweaning or weaning periods. However, calves in the MIX treatment had less neutral detergent fiber intake as a percentage of solid feed intake than CONT calves in the preweaning (23.3 vs. 37.0%) and weaning (23.5 vs. 25.8%) periods, although MIX calves sorted (107.2%) for long particles, which were primarily hay, during weaning. During the postweaning period, MIX calves had greater neutral detergent fiber intake as a percentage of solid feed intake compared with CONT calves (23.4 vs. 22.7%), although they sorted against long particles (84.4%), and decreased solid feed dry matter intake compared with CONT calves (3,292 vs. 3,536 g/d) and average daily gain (1.20 vs. 1.31 kg/d). Weaned calves in the MIX treatment also had lower plasma concentration of glucagon-like peptide 2 compared with CONT (0.46 vs. 0.77 ng/mg) but had higher plasma concentrations of ghrelin (0.05 vs. 0.03 ng/mg). These results suggest that feeding a mixture of texturized calf starter and chopped hay at the 90:10 ratio to postweaned calves may decrease solid feed intake and growth.
本研究旨在探讨向奶牛犊牛提供混合有小牛代乳料的干草对其固体饲料采食量、饲料分拣、生长以及血浆代谢物和激素浓度的影响。40 头荷斯坦小母牛在运输到研究农场（4-7 日龄）到 90 日龄期间，自由采食经膨化处理的小牛代乳料（粗蛋白 23.4%，干物质基础上淀粉 32.3%）和切碎的 Klein 草干草（CONT），或按照干物质基础上 90:10 的比例混合的相同代乳料和干草（MIX）。在研究之前，小母牛每天最多可摄入 557 克牛奶代乳料（粗蛋白 28%，脂肪 15%），从第 14 天到第 20 天每天摄入 737 克，从第 21 天到第 41 天每天摄入 1105 克，从第 42 天到第 48 天每天摄入 737 克，从第 49 天到第 55 天每天摄入 557 克。小母牛在第 56 天完全断奶。使用宾夕法尼亚州立颗粒分离器评估 MIX 犊牛的饲料分拣情况；分拣指数计算为实际摄入量与预测摄入量的百分比，超过 100%表示分拣为，低于 100%表示分拣为。在断奶前和断奶期间，处理方式均未影响固体饲料采食量、生长性能或血浆代谢物或激素浓度。然而，与 CONT 犊牛相比，MIX 处理组的犊牛在断奶前（23.3%比 37.0%）和断奶期间（23.5%比 25.8%）的中性洗涤纤维摄入量占固体饲料摄入量的比例较低，尽管 MIX 处理组的犊牛在断奶期间（107.2%）分拣出较长的颗粒，这些颗粒主要是干草。在断奶后阶段，与 CONT 犊牛相比，MIX 处理组的犊牛的中性洗涤纤维摄入量占固体饲料摄入量的比例更大（23.4%比 22.7%），但他们对长颗粒（84.4%）进行了分拣，与 CONT 犊牛相比，固体饲料干物质摄入量减少（3292 克/天比 3536 克/天）和平均日增重（1.20 千克/天比 1.31 千克/天）也减少。与 CONT 组相比，MIX 处理组的断奶犊牛的胰高血糖素样肽 2 血浆浓度也较低（0.46 比 0.77ng/mg），但生长激素释放肽（ghrelin）的血浆浓度较高（0.05 比 0.03ng/mg）。这些结果表明，向断奶后的犊牛提供 90:10 比例的膨化小牛代乳料和切碎干草的混合物可能会降低固体饲料采食量和生长速度。
