Abstract
Compensatory gain in cattle was studied to determine if age, previous rate of gain or size were factors of importance. A factorial experiment was conducted with growing diet regimen (control vs restricted), age [spring-born (older) vs fall-born (younger)] and breed (Angus vs Charolais) as the factors. During a growing phase, the two diets, (control = dehydrated alfalfa pellets; restricted = cubed grass-alfalfa hay, cottonseed hulls and soybean meal) were fed to both the older and younger steers of each breed to provide groups of similar age but different weights (growing regimen within age) and groups of similar weights but different ages (older-restricted vs younger-controls) at the time at which the steers were switched to a high concentrate diet. Interactions of breed with age and previous growing regimen diet on digestibility of some nutrients in the finishing diet were evident. During the growing phase, control steers averaged .72 kg/d gain, whereas the restricted steers averaged .25 kg/d. The older-restricted steers compensated (P<.05) from 30 to 120 d after the beginning of the feedlot phase compared with older-control steers. Rates of gain of younger steers were intermediate to those of the older steers throughout the finish phase and were not influenced by growing diet, except on d 30. Rate of gain during the growing phase was negatively correlated (P<.05) with rate of gain during the finishing phase (60 to 120 d). Within breed, weight at the beginning of the feedlot phase also was negatively correlated with gain during the finishing phase. Skeletal growth was reduced (P<.05) by the restricted diet during the growing phase, and small compensation (P>.05) was observed during the finishing phase. Feed/gain for restricted steers was slightly lower (P>.05) than control steers. Younger steers were more efficient (P<.05) overall in converting dry matter to gain, due to the relatively shorter growing phase when compared with the older steers. These data indicate that both previous gain and weight upon realimentation are influential on compensatory growth. Copyright © 1986. American Society of Animal Science. Copyright 1986 by American Society of Animal Science.