J Anim Sci. 2017 Nov;95(11):5012-5019. doi: 10.2527/jas2017.1783.
The objectives of this experiment were to determine the association of circulating cortisol, lactate, and glucose at, and prior to, weaning with ADG and incidences of bovine respiratory disease (BRD) in beef cattle. A blood sample was collected approximately 3 wk prior to weaning and at weaning from genetically diverse steers and heifers ( = 451). Cattle were weighed periodically throughout the study and ADG was calculated for the preweaning period (152 ± 15 d), the receiving period (45 d postweaning), the finishing period (200 d), and total postweaning ADG. Incidences of BRD were recorded and analyzed as a binary trait. Lung lesions were recorded at slaughter. Preweaning serum cortisol concentrations were positively associated ( = 0.040) with receiving ADG and explained 0.74% of the variance of receiving ADG. Preweaning glucose concentrations were positively associated ( < 0.001) with preweaning ADG and negatively associated with receiving ( = 0.003), finishing ( = 0.008), and total postweaning ADG ( = 0.002) and explained 2.0% of the variance in total postweaning ADG. Variation in preweaning serum glucose concentrations could be indicative of variation in milk consumption, and therefore indicate calves receiving less milk grow slower prior to weaning, but experience compensatory gain postweaning. Cattle that were diagnosed with BRD ( = 130) grew slower during the receiving phase ( = 0.004), but total postweaning ADG was not different from cattle not diagnosed with BRD ( = 0.683). Additionally, cattle that were diagnosed with BRD in the feedlot tended ( = 0.062) to have slightly lower preweaning serum glucose concentrations. Using a logistic regression analysis, none of the serum variables measured at or before weaning were predictive of developing BRD ( > 0.180). Weaning serum glucose concentrations tended to be predictive of the presence of lung lesions at weaning ( = 0.060). These data indicate that glucose measured early in life is associated with growth rate, and could indicate that carbohydrate metabolism could contribute to variation in ADG.
本实验的目的是确定循环皮质醇、乳酸和葡萄糖在断奶时以及断奶前与肉牛的日增重 (ADG) 和牛呼吸道疾病 (BRD) 发生率的关系。大约在断奶前 3 周和断奶时从遗传上不同的公牛和小母牛 ( = 451) 中采集血样。在研究过程中定期对牛进行称重，并计算断奶前 (152 ± 15 d)、接收期 (断奶后 45 d)、育肥期 (200 d) 和总断奶后 ADG 的日增重。记录 BRD 的发病率并作为二元性状进行分析。屠宰时记录肺部病变。断奶前血清皮质醇浓度与接收 ADG 呈正相关 ( = 0.040)，解释了接收 ADG 方差的 0.74%。断奶前血糖浓度与断奶前 ADG 呈正相关 ( < 0.001)，与接收呈负相关 ( = 0.003)、育肥 ( = 0.008) 和总断奶后 ADG ( = 0.002)，解释了总断奶后 ADG 方差的 2.0%。断奶前血清葡萄糖浓度的变化可能表明牛奶消耗的变化，因此表明断奶前接受较少牛奶的小牛生长速度较慢，但在断奶后会出现补偿性增长。被诊断患有 BRD 的牛 ( = 130) 在接收阶段生长速度较慢 ( = 0.004)，但与未被诊断患有 BRD 的牛相比，总断奶后 ADG 没有差异 ( = 0.683)。此外，在育肥场被诊断患有 BRD 的牛在断奶前血清葡萄糖浓度略低 ( = 0.062)。使用逻辑回归分析，断奶时或之前测量的血清变量均不能预测 BRD 的发生 ( > 0.180)。断奶时的血清葡萄糖浓度有预测肺部病变存在的趋势 ( = 0.060)。这些数据表明，生命早期测量的葡萄糖与生长速度相关，并且可能表明碳水化合物代谢可能导致 ADG 的变化。
