Moriel P, Artioli L F A, Poore M H, Confer A W, Marques R S, Cooke R F
J Anim Sci. 2015 Sep;93(9):4473-85. doi: 10.2527/jas.2015-9238.
We evaluated the effects of MP supply on growth performance before and after preconditioning and measurements of innate and humoral immune response of beef steers following vaccination. Angus steers ( = 36; BW = 231 ± 21 kg; age = 184 ± 18 d) were weaned on d -6, stratified by BW and age on d 0, and randomly assigned to 1 of 18 drylot pens (2 steers/pen). Treatments were assigned to pens (6 pens/treatment) and consisted of corn silage-based diets formulated to provide 85%, 100%, or 115% of the daily MP requirements of a beef steer gaining 1.1 kg/d from d 0 to 42. Steers were vaccinated against infectious bovine rhinotracheitis virus, bovine viral diarrhea (BVDV) types 1 and 2 viruses, and clostridium on d 14 and 28. Blood samples were collected on d 0, 14, 15, 17, 21, 28, 29, 30, 35, and 42. Body weight did not differ ( ≥ 0.17) among treatments from d 0 to 28. On d 42, 115% MP steers were heaviest, 100% MP steers were intermediate, and 85% MP steers were lightest ( = 0.05; 297, 290, and 278 ± 7 kg, respectively). Overall, ADG and G:F did not differ ( ≥ 0.13) between 100% and 115% MP steers and were least ( < 0.01) for 85% MP steers (1.2, 1.4, and 0.8 ± 0.07 kg/d and 0.23, 0.24, and 0.19 ± 0.008, respectively). Plasma haptoglobin (Hp) concentrations did not differ among treatments ( ≥ 0.46), whereas plasma ceruloplasmin (Cp) concentrations were greatest ( ≤ 0.04) for 85% MP steers, intermediate for 100% MP steers, and least for 115% MP steers on d 30, 35, and 42. Plasma cortisol concentrations were greater ( ≤ 0.03) for 85% vs. 100% and 115% MP steers on d 14 and 28. Liver mRNA expression of Cp and Hp and muscle mRNA expression of m-calpain, mammalian target of rapamycin, and ubiquitin did not differ among treatments ( ≥ 0.17). Serum neutralization titers to BVDV-1b titers were greater ( ≤ 0.02) for 115% vs. 85% and 100% MP steers on d 42 (5.8, 3.0, and 3.7 ± 0.60 log, respectively), whereas mean serum leukotoxin titers were greater for 85% vs. 100% and 115% MP steers (3.1, 2.4, and 2.5 ± 0.21 log, respectively). Preconditioning MP supply did not affect ( ≥ 0.26) ubsequent finishing growth performance and carcass characteristics. Thus, increasing MP supply from 85% to 115% of daily requirement of preconditioning beef steers had variable results on innate and humoral immune response and enhanced growth performance during a 42-d preconditioning period without affecting carcass characteristics at slaughter.
我们评估了在预适应前后补充代谢蛋白（MP）对育肥牛生长性能的影响，以及接种疫苗后其先天性和体液免疫反应的测定结果。安格斯育肥牛（n = 36；体重 = 231 ± 21千克；年龄 = 184 ± 18天）在第 -6天断奶，在第0天按体重和年龄分层，然后随机分配到18个干栏舍中的1个（每栏2头牛）。处理方式分配到栏舍（每个处理6栏），日粮以玉米青贮为基础，配方设计为从第0天到42天为日增重1.1千克的育肥牛提供85%、100%或115%的每日MP需求量。在第14天和28天给育肥牛接种传染性牛鼻气管炎病毒、1型和2型牛病毒性腹泻（BVDV）病毒以及梭菌疫苗。在第0、14、15、17、21、28、29、30、35和42天采集血样。从第0天到28天，各处理组间体重无差异（P≥0.17）。在第42天，115% MP组的育肥牛最重，100% MP组的育肥牛体重居中，85% MP组的育肥牛最轻（P = 0.05；分别为297、290和278 ± 7千克）。总体而言，100%和115% MP组育肥牛的平均日增重（ADG）和料重比（G:F）无差异（P≥0.13），85% MP组的ADG和G:F最低（P < 0.01）（分别为1.2、1.4和0.8 ± 0.07千克/天以及0.23、0.24和0.19 ± 0.008）。各处理组间血浆触珠蛋白（Hp）浓度无差异（P≥0.46），而在第30、35和42天，85% MP组育肥牛的血浆铜蓝蛋白（Cp）浓度最高（P≤0.04），100% MP组育肥牛的Cp浓度居中，115% MP组育肥牛的Cp浓度最低。在第14天和28天，85% MP组育肥牛的血浆皮质醇浓度高于100%和115% MP组（P≤0.03）。肝脏中Cp和Hp的mRNA表达以及肌肉中m - 钙蛋白酶、雷帕霉素靶蛋白和泛素的mRNA表达在各处理组间无差异（P≥0.17）。在第42天，115% MP组育肥牛对BVDV - 1b的血清中和滴度高于85%和100% MP组（P≤0.02）（分别为5.8、3.0和3.7 ± 0.60 log），而85% MP组育肥牛的平均血清白细胞毒素滴度高于100%和115% MP组（分别为3.1、2.4和2.5 ± 0.21 log）。预适应期的MP供应不影响（P≥0.26）后续育肥期的生长性能和胴体特性。因此，将预适应期育肥牛的MP供应量从每日需求量的85%提高到115%，在42天的预适应期内对先天性和体液免疫反应产生了不同的影响，并提高了生长性能，且不影响屠宰时的胴体特性。
