Relationships between residual feed intake and feedlot performance, profitability, and carcass traits in Brahman cattle

ABSTRACT The present study aimed to evaluate the feedlot performance, profitability and carcass traits of Brahman bulls classified according to the residual feed intake (RFI). Twenty-four bulls (19-month old, 370±34kg live weight) were housed in individual pens for 54 days and had the daily feed intake (observed dry matter intake, DMIobs; DMI % live weight, LW) and average daily gain (ADG) measured. Ultrasound carcass evaluations were performed at the initial and final weighings, when measurements were taken of Longissimus dorsi area, ratio, Longissimus and Biceps femoris fat thickness. The animals were ranked and divided into high (>+0.5 standard deviation; SD), medium (between ±0.5 SD from the mean), and low (0.05). Low-RFI animals showed lower weight gain cost and higher daily profit (P<0.05). Carcass traits were similar between groups, regardless of evaluation date (P>0.05). Selection for RFI lead to animals with lower feed intake without affecting weight gain or carcass traits, thereby providing increased profitability for beef cattle farming.

摘要：本研究旨在评估按剩余采食量（residual feed intake, RFI）分级的婆罗门公牛（Brahman bulls）的育肥性能、养殖效益与胴体性状。选取24头19月龄、活体重为370±34kg的婆罗门公牛，采用单栏饲养模式饲养54天，测定其每日采食量[实测干物质采食量（observed dry matter intake, DMI_obs）、采食量占活体重百分比（DMI % LW）]及平均日增重（average daily gain, ADG）。在试验初始与终末称重时，通过超声扫描开展胴体性状测定，检测指标包括背最长肌面积、背膘厚比值、背最长肌与股二头肌脂肪厚度。按剩余采食量将试验牛分为高剩余采食量组（>均值+0.5标准差，SD）、中剩余采食量组（介于均值±0.5标准差区间内）与低剩余采食量组（0.05）。结果显示，低剩余采食量组公牛的增重成本更低、日收益更高（P<0.05）；各组间胴体性状无显著差异，且不受测定时间的影响（P>0.05）。针对剩余采食量进行选育，可在不影响增重效果与胴体性状的前提下降低采食量，从而提升肉牛养殖业的经济效益。