Compensatory Growth Responses of Fattening Steers Following Various Low Energy Intake Regimes on Hay or Irrigated Pasture

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Abstract
Weanling beef steers were used to investigate the influence of various levels of energy intake produced by various types of roughage during the growing phase on subsequent compensatory growth responses in the feedlot. Body composition, feed intake on pasture, and total feed requirements were measured. The design consisted of three major periods. Period 1 had three experimental treatments: high, medium and low energy intakes. Steers from the medium and low energy intake groups were each randomized to four energy intake treatments in period 2. Period 3 followed with all steers receiving a high energy ration. Representative steers were slaughtered prior to the start of the experiment and at the end of each period, and body composition was determined. Compensatory growth was demonstrated in each period following a low energy intake period, even though the animals were realimented at different planes of nutrition. Not only did compensatory growth response occur in terms of empty body weight gain or caloric gain, but the carcass characteristics, fat content, back-fat thickness, marbling score and rib-eye area were enhanced. When a liberal to low energy intake of 124 days on pasture intervened before realimentation, there was no significant compensatory growth response. Improvement in partial efficiency of feed utilization and feed capacity were shown to be responsible for compensatory growth. The lowest total net energy requirement was for steers given the high energy intake after weaning, followed by those realimented on the high energy intake subsequent to low or medium energy intakes after weaning. Steers given a fattening ration following a low, medium, or liberal energy intake did not differ in total net energy requirements (restricted plus realimented periods), even though varying lengths of time were required to reach equal final empty body energy. Apparently compensatory growth was responsible. Copyright © 1965. American Society of Animal Science . Copyright 1965 by American Society of Animal Science