Department of Agriculture, College of Agricultural Sciences and Natural Resources, Texas A&M University - Commerce, Commerce, TX, USA.
Department of Animal Science, University of Tennessee Institute of Agriculture, University of Tennessee, Knoxville, TN, USA.
BMC Res Notes. 2023 Aug 18;16(1):177. doi: 10.1186/s13104-023-06444-6.
Blood chemistry may provide indicators to greater feed efficient cattle. As a side objective to previous research, 17 Angus heifers approximately two years old underwent a feed efficiency trial to determine residual feed intake (RFI) and identify variation in blood chemistry in beef cattle divergent in feed efficiency. Heifers were categorized as high- or low-RFI based ± 0.25 standard deviations around mean RFI. Blood samples were analyzed using an i-STAT handheld blood analyzer to measure sodium, potassium, glucose, blood urea nitrogen (BUN), creatinine, hematocrit, and hemoglobin. BUN was greater in high-RFI heifers (µ = 8.7 mg/dL) contrasted to low-RFI heifers (µ = 6.5 mg/dL; P = 0.01), whereas glucose was greater in low-RFI heifers (µ = 78.1 mg/dL) contrasted to high-RFI heifers (µ = 82.0 mg/dL; P = 0.05). No other blood chemistry parameters differed by RFI. The greater abundance of BUN in high-RFI heifers may indicate inefficient utilization of protein or mobilization of tissue protein for non-protein use. Greater blood glucose concentrations in low-RFI heifers may indicate greater utilization of energy precursors, such as volatile fatty acids, or metabolites. These data suggest there are readily measurable indicators of physiological variation in nutrient utilization; however, this warrants additional studies to explore.
血液化学可以为更具饲料效率的牛提供指标。作为之前研究的一个次要目标，17 头大约两岁的安格斯小母牛进行了饲料效率试验，以确定剩余饲料摄入量 (RFI) 并确定在饲料效率上存在差异的肉牛血液化学中的变化。小母牛根据平均 RFI 的 ± 0.25 个标准差被归类为高或低 RFI。使用 i-STAT 手持式血液分析仪分析血液样本，以测量钠、钾、葡萄糖、血尿素氮 (BUN)、肌酐、红细胞压积和血红蛋白。高 RFI 小母牛的 BUN 较高（µ = 8.7 mg/dL），与低 RFI 小母牛（µ = 6.5 mg/dL；P = 0.01）相比，而低 RFI 小母牛的葡萄糖较高（µ = 78.1 mg/dL），与高 RFI 小母牛（µ = 82.0 mg/dL；P = 0.05）相比。RFI 没有其他血液化学参数不同。高 RFI 小母牛中 BUN 的丰度较高可能表明蛋白质利用效率低下或组织蛋白质动员用于非蛋白质用途。低 RFI 小母牛中血液葡萄糖浓度较高可能表明更多地利用了能量前体，如挥发性脂肪酸或代谢物。这些数据表明存在易于测量的营养利用生理变化指标；然而，这需要进一步的研究来探讨。
