Obeidat B S, Cobb C J, Sellers M D, Pepper-Yowell A R, Earleywine T J, Ballou M A
Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409; Department of Animal Production, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, Jordan.
Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409.
J Dairy Sci. 2013;96(11):7155-7166. doi: 10.3168/jds.2013-6699. Epub 2013 Sep 12.
Two experiments were conducted to determine the influence of plane of nutrition during (1) the pre- and immediate postweaning periods and (2) the grower phase on the performance and leukocyte responses of Holstein calves. In experiment 1, 39 (2 ± 1 d old) colostrum-fed heifer calves were randomly assigned to 2 planes of nutrition, a low (LPN; n = 19) and a high plane of nutrition (HPN; n = 20). Calves in the LPN treatment were offered 418 g/d of dry matter (DM) of a 20% crude protein (CP)/20% fat milk replacer, whereas calves in the HPN treatment were offered 747 and 1,010 g/d of DM of a 28% CP/20% fat milk replacer during wk 1 and wk 2 to 6, respectively. Calves were offered ad libitum access to a calf starter until the end of the study. Peripheral blood samples were collected on d 3, 10, 21, 45, 47, 53, and 91 for many ex vivo leukocyte responses and biochemical analyses. A nutrition × time interaction was present for average daily gain and feed efficiency (feed:gain ratio). A nutrition × time interaction existed for plasma glucose concentration. Neutrophil L-selectin expression was greater in calves fed the LPN than HPN on d 3 and 21. The percentage of neutrophils producing an oxidative burst (OB) when cocultured with Escherichia coli tended to be greater and was greater in calves fed the LPN than HPN on d 10 and 21, respectively. In addition, neutrophils from calves fed the LPN had greater OB intensity throughout the neonatal period (0 to 21 d). However, plasma haptoglobin was not different between the 2 planes of nutrition throughout the study. In experiment 2, 50 heifer calves that were all previously fed a HPN similar to that described for experiment 1 were randomly assigned to 2 planes of nutrition (HPN and LPN) during the grower phase (5 pens/treatment; 5 calves/pen). Calves fed the HPN during the grower phase were fed 4.1 kg of concentrate DM (pellets; 22.4% CP, DM basis) per head per day, whereas calves on the LPN during the grower phase were fed 1.6 kg of DM of the same concentrate per head per day. All calves were fed alfalfa hay (16.2% CP; DM basis) ad libitum. Overall, average daily gain was greater in HPN calves than LPN calves. No differences were noticed for concentrations of plasma urea nitrogen, glucose, neutrophil L-selectin expression, percentage of neutrophils producing OB, and plasma haptoglobin concentration between the 2 planes of nutrition. In summary, intake and performance were improved in calves fed the HPN than calves fed the LPN in both experiments. The neutrophil responses of calves fed an LPN were more active during the preweaning period than calves fed an HPN; however, this response was not observed during the immediate postweaning period or the grower phase.
进行了两项试验，以确定（1）断奶前和断奶后即刻阶段以及（2）生长育肥阶段的营养水平对荷斯坦犊牛生产性能和白细胞反应的影响。在试验1中，39头（2±1日龄）初乳饲喂的小母牛犊被随机分配到2种营养水平，即低营养水平（LPN；n = 19）和高营养水平（HPN；n = 20）。LPN处理组的犊牛饲喂含20%粗蛋白（CP）/20%脂肪的代乳粉，每天提供418 g干物质（DM），而HPN处理组的犊牛在第1周以及第2至6周分别饲喂含28% CP/20%脂肪的代乳粉，每天提供747 g和1010 g DM。在研究结束前，犊牛可自由采食开食料。在第3、10、21、45、47、53和91天采集外周血样本，用于多项体外白细胞反应和生化分析。平均日增重和饲料效率（料重比）存在营养水平×时间的交互作用。血浆葡萄糖浓度存在营养水平×时间的交互作用。在第3天和第21天，LPN组犊牛的中性粒细胞L-选择素表达高于HPN组。与大肠杆菌共培养时，产生氧化爆发（OB）的中性粒细胞百分比在第10天和第21天LPN组犊牛中趋于更高且高于HPN组。此外，LPN组犊牛的中性粒细胞在整个新生期（0至21天）具有更高的OB强度。然而，在整个研究过程中，两种营养水平下血浆触珠蛋白无差异。在试验2中，50头之前均饲喂与试验1中所述类似的HPN的小母牛犊在生长育肥阶段被随机分配到2种营养水平（HPN和LPN）（每个处理5个圈舍；每个圈舍5头犊牛）。生长育肥阶段饲喂HPN的犊牛每天每头饲喂4.1 kg精料DM（颗粒料；CP含量22.4%，以DM计），而生长育肥阶段处于LPN的犊牛每天每头饲喂1.6 kg相同精料的DM。所有犊牛自由采食苜蓿干草（CP含量16.2%，以DM计）。总体而言，HPN组犊牛的平均日增重高于LPN组犊牛。两种营养水平之间血浆尿素氮、葡萄糖浓度、中性粒细胞L-选择素表达、产生OB的中性粒细胞百分比以及血浆触珠蛋白浓度均未发现差异。总之，在两项试验中，饲喂HPN的犊牛比饲喂LPN的犊牛采食量和生产性能更高。断奶前阶段，饲喂LPN的犊牛中性粒细胞反应比饲喂HPN 的犊牛更活跃；然而，在断奶后即刻阶段或生长育肥阶段未观察到这种反应。
