Gohary K, Leslie K E, Ford J, Capel M, LeBlanc S J, Duffield T F
Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
Perry Veterinary Clinic, Perry, NY 14530.
J Dairy Sci. 2015 Jul;98(7):4392-400. doi: 10.3168/jds.2014-8235. Epub 2015 Apr 29.
The effect of administering recombinant bovine somatotropin (rbST) to cows with hyperketonemia during the early postpartum period on health, metabolic parameters, milk production, and early reproductive performance was evaluated in a double-blinded clinical trial. Cows from 8 dairy herds in New York State were tested weekly between 3 and 16d in milk for elevated serum β-hydroxybutyrate. Cows were enrolled in the study when blood β-hydroxybutyrate was ≥1.3mmol/L for the first time. Enrolled cows were randomly assigned to a treatment (n=273) or placebo control (n=270) group. Treated cows were given 325mg of rbST subcutaneously on the day of enrollment and again 14d later. Control cows received the same regimen except the syringe contained only the carrier without somatotropin. After enrollment, blood samples were collected weekly for 4wk and submitted to the laboratory to be analyzed for selected metabolites. Risk ratios for clinical diseases subsequent to treatment were calculated using Poisson regression. Continuous data were analyzed using linear mixed models. Time to first insemination was assessed with survival analysis. In the 42d following the first administration of rbST, incidence risks of displaced abomasum, clinical ketosis, metritis, clinical mastitis, and lameness were not different between treatment groups. Cows treated with rbST had a slightly lower body condition score 28d after enrollment compared with control cows. In the 4wk following enrollment, serum nonesterified fatty acids and aspartate amino-transferase were slightly higher for treated than control cows, respectively. Serum glucose, calcium, haptoglobin, and β-hydroxybutyrate were similar between groups. Treatment had no effect on resolution of hyperketonemia in any of the 4wk after enrollment. Milk production in either of the 2-wk periods after each treatment was not different between treated and control cows. Furthermore, milk production was not different between groups from enrollment to 98d in milk (42.6±0.6 and 42.1±0.7kg/d for treatment and control groups, respectively). Treatment had no effect on time to first insemination (83 and 74d in milk for treatment and control groups, respectively; hazard ratio=0.72) or first insemination pregnancy risk (27 and 29% for treatment and control groups, respectively; risk ratio=0.92). Based on the current results, it is not recommended to use a low dose of rbST as therapy for cows with hyperketonemia.
在一项双盲临床试验中，评估了在产后早期给患有酮血症的奶牛注射重组牛生长激素（rbST）对其健康、代谢参数、产奶量和早期繁殖性能的影响。对纽约州8个奶牛场的奶牛在产奶3至16天期间每周进行一次检测，以检测血清β-羟基丁酸水平是否升高。当血液β-羟基丁酸首次≥1.3mmol/L时，奶牛被纳入研究。纳入的奶牛被随机分为治疗组（n = 273）或安慰剂对照组（n = 270）。治疗组奶牛在入组当天皮下注射325mg rbST，并在14天后再次注射。对照组奶牛接受相同的给药方案，但注射器中仅含有不含生长激素的载体。入组后，每周采集血样，持续4周，并提交实验室分析选定的代谢物。使用泊松回归计算治疗后临床疾病的风险比。连续数据使用线性混合模型进行分析。通过生存分析评估首次授精的时间。在首次注射rbST后的42天内，治疗组和对照组之间真胃移位、临床酮病、子宫炎、临床乳腺炎和跛行的发病风险没有差异。与对照组奶牛相比，治疗组奶牛在入组28天后体况评分略低。在入组后的4周内，治疗组奶牛的血清非酯化脂肪酸和天冬氨酸转氨酶分别略高于对照组奶牛。两组之间的血清葡萄糖、钙、触珠蛋白和β-羟基丁酸相似。治疗对入组后4周内任何一周的酮血症缓解均无影响。每次治疗后两个2周期间的产奶量在治疗组和对照组奶牛之间没有差异。此外，从入组到产奶98天，两组之间的产奶量没有差异（治疗组和对照组分别为42.6±0.6和42.1±0.7kg/d）。治疗对首次授精时间（治疗组和对照组产奶天数分别为83天和74天；风险比 = 0.72）或首次授精妊娠风险（治疗组和对照组分别为27%和29%；风险比 = 0.92）没有影响。基于目前的结果，不建议使用低剂量rbST治疗患有酮血症的奶牛。
