Characterization of energetically efficient and inefficient beef cows.

摘要: Dry matter intake and BW data from 14 mature, nonpregnant, nonlactating Angus cows that were individually fed through two consecutive 70- to 80-d periods (maintenance ad libitum) used predict ADG (ADG = -.512 + .213 DMI - .0017 BW, R2 .95). This equation then was identify feed efficiency types among these cows. Cows identified as average type (A) if within one SE of predicted ADG, efficient (E) or inefficient (I) exceeded above below, respectively, its ADG. Four, four, six grouped I, A, E types, respectively. During the maintenance period, DM ME similar (P greater than .10) across all three types. But during libitum voluntary intakes I less .05) those A Average daily gains feeding Daily required for highest, intermediate, lowest (180.2, 154.6, 135.1 kcal/kg BW.75, respectively). Inefficient tended have fat deposited more protein (137.9 vs 77.2 46.2 g/d, Concurrent with higher accretion rates, liver weights heavier (8.58 7.79 7.68 kg, characterized by energy requirements maintenance. Their high may partially explain their requirements.