Department of Animal Science, Faculty of Agriculture, Lorestan University, PO Box 465, Khorramabad, Iran 44316-68151.
Department of Animal Science, Faculty of Agriculture, Lorestan University, PO Box 465, Khorramabad, Iran 44316-68151.
J Dairy Sci. 2018 May;101(5):4143-4157. doi: 10.3168/jds.2017-13990. Epub 2018 Feb 22.
We investigated the interactive effects of forage source and forage particle size (PS) as a free-choice provision on growth performance, rumen fermentation, and behavior of dairy calves fed texturized starters. Forty-eight Holstein calves (42 ± 3 kg of body weight) were randomly assigned (n = 12 calves per treatment) in a 2 × 2 factorial arrangement of treatments with the factors of forage source [alfalfa hay (AH) and wheat straw (WS)] and forage PS [(AH: medium = 1.96 mm or long = 3.93 mm) and (WS: medium = 2.03 mm or long = 4.10 mm), as geometric mean diameters]. The treatments were (1) AH with medium PS (AH-MPS), (2) AH with long PS (AH-LPS), (3) WS with medium PS (WS-MPS), and (4) WS with long PS (WS-LPS). Regardless of forage PS, the preweaning starter intake, dry matter intake, metabolizable energy intake, weaning body weight, and forage intake were greater for AH calves than WS calves. Average daily gain, average daily gain/metabolizable energy intake, feed efficiency, and final body weight of the calves did not differ among groups. An interaction of forage source and forage PS influenced acetate, propionate, and acetate-to-propionate ratio in the rumen on d 35, with the greatest acetate proportion and acetate-to-propionate ratio, but the least propionate proportion for AH-MPS calves than the other calves. The total volatile fatty acid concentration and the rumen proportions of propionate (d 70), butyrate (d 35), and valerate (d 35) were greater in AH-MPS calves than in AH-LPS calves. Calves fed AH had greater total volatile fatty acid concentration (d 35 and 70) and propionate proportion (d 70), but lesser ruminal proportions of butyrate (d 35 and 70), valerate (d 35 and 70), and acetate-to-propionate ratio (d 70) compared with calves fed WS. The ruminal valerate proportion (d 70) was greatest in WS-MPS calves than the other calves. An interaction of forage source and forage PS influenced preweaning standing time and starter eating time, with the least standing time for WS-MPS calves and the greatest eating starter time for AH-LPS calves. Calves fed AH spent less time for rumination, but devoted more time to non-nutritive oral behaviors than WS calves. Calves fed forage with long PS spent more time for rumination, eating forage, and spent less time lying and non-nutritive oral behaviors than medium PS. In conclusion, forage source and PS interacted, affecting behavior and rumen fermentation when calves were fed texturized starters. In addition, a desirable ruminal pH in dairy calves can be obtained with texturized starters.
我们研究了作为自由选择提供的饲料来源和饲料颗粒大小（PS）的交互作用对食用膨化启动器的奶牛犊牛生长性能、瘤胃发酵和行为的影响。48 头荷斯坦奶牛（42±3kg 体重）被随机分配（每处理 12 头奶牛），处理因素为饲料来源[苜蓿干草（AH）和小麦秸秆（WS）]和饲料 PS[（AH：中=1.96mm 或长=3.93mm）和（WS：中=2.03mm 或长=4.10mm）]。处理为（1）AH 与中 PS（AH-MPS），（2）AH 与长 PS（AH-LPS），（3）WS 与中 PS（WS-MPS）和（4）WS 与长 PS（WS-LPS）。无论饲料 PS 如何，与 WS 犊牛相比，AH 犊牛的预断奶启动器摄入量、干物质摄入量、可代谢能量摄入量、断奶体重和饲料摄入量更大。犊牛的平均日增重、平均日增重/可代谢能量摄入量、饲料效率和最终体重在各组之间没有差异。饲料来源和饲料 PS 的相互作用影响了第 35 天瘤胃中的乙酸、丙酸和乙酸/丙酸比，与其他犊牛相比，AH-MPS 犊牛的乙酸比例和乙酸/丙酸比最大，但丙酸比例最小。第 70 天，AH-MPS 犊牛的总挥发性脂肪酸浓度和瘤胃丙酸（d70）、丁酸（d35）和戊酸（d35）比例大于 AH-LPS 犊牛。与 WS 犊牛相比，AH 犊牛的总挥发性脂肪酸浓度（d35 和 70）和丙酸比例（d70）更高，但瘤胃丁酸（d35 和 70）、戊酸（d35 和 70）和乙酸/丙酸比（d70）的比例较低。与其他犊牛相比，WS-MPS 犊牛的瘤胃戊酸比例（d70）最大。饲料来源和饲料 PS 的相互作用影响了预断奶站立时间和启动器采食时间，与 WS-MPS 犊牛相比，站立时间最短，AH-LPS 犊牛的采食启动器时间最长。与 WS 犊牛相比，AH 犊牛的反刍时间更少，但非营养性口腔行为更多。与中 PS 相比，采食长 PS 的犊牛反刍时间更长，采食饲料时间更长，躺卧和非营养性口腔行为时间更短。总之，当犊牛食用膨化启动器时，饲料来源和 PS 相互作用，影响行为和瘤胃发酵。此外，膨化启动器可以使奶牛犊牛获得理想的瘤胃 pH 值。
