Effects of feeding level on growth, composition of gain, carcass quality and mature body size in steers at ages up to six years.

Tissue gain and efficiency and carcass characteristics of seventy-eight Angus steers were compared on three feed intake regimens and serially slaughtered at 6 months to 6 years. The regimens were: (A) continuous ad ad libitum feeding, (B) restricted to gain about 0.45 kg daily and (C) restricted as in B until 6 months before slaughter then fed ad libitum. Steers, regardless of feeding regimen, made their greatest gains up to 12 months of age and became less efficient after that time. Steers fed ad libitum had the highest percentage of fat but the lowest percentage of lean and bone when compared with steers fed for restricted gain. Carcasses of the steers fed ad libitum contained more lean and fat at each slaughter age. Average daily gain, feed efficiency and percentage of lean and bone decreased with age; and feed intake, slaughter grade, dressing percent, taste panel desirability and percent of fat tended to increase with age. All steers reached their maximum growth in height at withers, depth of chest and length of body at about 3 years. Steers that were restricted up to 6 months before slaughter showed compensatory growth during their ad libitum feeding period and during the first 12 months of the study; protein and fat were produced most efficiently by this growth. It would appear that it is possible to modify fat deposition by changing feed intake level.