Nutritional Management Affects Feedlot Performance, Carcass Characteristics and the Relationships of Intramuscular Fat, Subcutaneous Fat, and Feed Efficiency of Normal and Early -Weaned Heifers

Abstract

Effects of age at feedlot entry and breed on the relationships of 12 th rib fat, marbling score and feed efficiency were evaluated using ultrasound technology. The data suggested that early weaning heifers and finishing them as calves resulted in more efficient gains (P ≤ 0.01) at any given marbling score and higher marbling scores at any given subcutaneous fat thickness (P ≤ 0.05) when compared to heifers grazed on pasture and finished as two-year-olds. When compared to heifers grazed on pasture and finished as yearlings, heifers finished as calves gained more efficiently at any given fat thickness (P ≤ 0.01) and deposited intramuscular fat at a faster (P ≤ 0.01) rate relative to subcutaneous fat. As two-year-olds, Angus heifers tended to gain more efficiently (P ≤ 0.10) at any given fat thickness than Wagyu two-year-olds. However, Wagyu two-year-olds had higher marbling scores at any given subcutaneous fat thickness (P ≤ 0.01). As calves, breed did not affect these relationships. Limit-feeding strategies and ultrasound imaging may serve as management tools in improve feed efficiency and carcass quality.