Growth performance and carcass composition in beef heifers undergoing catch-up (compensatory) growth

Fifty-three Hereford crossbred heifers (211 ± 28 (mean ± SD) kg; 197 ± 13 d of age at day 1) were used to study catch-up growth and its effects on carcass composition. Five heifers were slaughtered on day 1; the remaining 48 were randomly penned in groups of six and assigned to treatments as follows: three pens to ad libitum feeding (target gain > 1.0 kg d −1 ); three pens to 2 mo of feed restriction (target gain 0.5 kg d −1 ); followed by realimentation; and two pens to 4 mo of feed restriction (target gain: 2 mo at 0.5 kg d −1 and 2 mo at 0.0 kg d −1 ) followed by realimentation. Animals from one pen were slaughtered from each treatment after 2 mo, after 4 mo, and at a final slaughter weight of about 410 kg. During the final period (4 mo to slaughter), growth rate was greater (P < 0.05) in the 4-mo than in the 2-mo restricted–realimented animals or the ad-libitum-fed animals (1.91 vs. 1.18 vs. 1.02 kg d −1 ), respectively. Feed restriction for 2 mo had no significant effect on the composition of the three-rib cut, but 4 mo of feed restriction was associated with significantly lower and higher (P < 0.05) proportions of fat and bone, respectively, in the three-rib cut. Muscle proportion was not affected by treatment. At the final slaughter weight, no significant differences were found among treatments in the tissue proportions of the three-rib cut. It is concluded that 2 or 4 mo of feed restriction, starting at 6 mo of age, has no permanent effect on a heifer's live weight or body composition.