Restricted feeding management for finishing cattle: Effects on performance, carcass traits, economics, body composition, ruminal fermentation and blood metabolite and hormonal profiles

Scope and method of study. This study consisted of four trials. The first trial (n = 27) examined the effects of two previous intake (ad libitum vs restricted) and two diet types (concentrate vs roughage) on subsequent finishing performance, carcass characteristics and body composition. Trial 2 (n = 144) examined the effects of a 15% feed intake restriction for half the feeding period followed by ad libitum feeding versus ad libitum feeding throughout. Feedlot performance, carcass characteristics and economics were the response variables. Trial 3 (n = 73) examined the effects of a 7.5 and 15% restriction at two different protein levels for 300 lbs of gain followed by ad libitum feeding at a common protein level for the remainder of the feeding period. Performance, carcass traits and body composition and organ weights were the response variables measured. The fourth trial (n = 10) examined the effects of a 15% restriction in feed intake for half the feeding period followed by ad libitum feeding vs ad libitum feeding throughout on feeding behavior, ruminal fermentation and blood hormonal and metabolite profiles.; Findings and conclusions. In trial 1 restricted feeding of a high concentrate diet early in the feeding period tended to produce more efficient gains than cattle fed high roughage diets early or high concentrate diets at ad libitum intakes. Previous intake level had no effect on subsequent intake level or variation in intake. In trial 2 limit feeding improved overall feedlot efficiency and with the exception of slightly lower carcass weights had no adverse effects on any measured carcass traits. Limit fed cattle were more profitable when sold on a live weight basis and ad libitum fed cattle were more profitable when sold on a carcass value system, however, this was solely accounted for by the heavier carcass weights and not carcass merit. In trial 3, similar to the other trials restricting intake for a period of time prior to ad libitum feeding resulted in lower feed intakes, slightly lower overall gains and improved feed efficiencies. The additional protein proved to be of value only at the greater restriction level. Similarly, there were no differences in any of the measured carcass traits. In trial 4, during the limit fed cattle consumed a greater proportion of their daily feed allotment within two hours (90.3 vs 60.8%), but similarly during the ad libitum period. Although neither blood glucose nor insulin was affected by feeding treatment, blood concentrations of both Growth hormone and free fatty acids were reduced when cattle were limit fed. Limit fed animals had a greater proportion of propionate in the rumen during the limit feeding period. (Abstract shortened by UMI.)...