Developmental changes in beef steers as influenced by fattening, age and type of ration

Abstract

1. The effect of fattening, age and the ratio of concentrates to roughage in a ration on the development of beef steers was investigated. The specific purpose was to study developmental patterns during the short-term fattening of beef steers of different ages in order to ascertain to what extent beef steers improved in the proportions of the various body parts, offals, organs and tissues.2. The experimental material consisted of 104 beef steers of three age-groups, namely, ± 8, ± 20 and ± 32 months old, fed on rations differing in the ratio of concentrates to roughage and 36 control steers of the same age-groups, slaughtered at the start of the experiment.3. When the weights of the parts of the carcasses were expressed as a percentage of the carcass weight, it was found that with the exception of a few parts, the percentage which the parts constituted of the carcass remained remarkably constant in the various groups. The effect of age in both the fattened and unfattened groups was comparatively small, whilst the effect of fattening was of slightly greater magnitude. The effect of the ration concentration per se was negligible.4. The parts where fat was deposited formed a significantly (P < 0·01) larger percentage of the carcass of the fattened than of the unfattened steers (kidney and channel fat, thin flank and cod, brisket, plate and neck).5. The shoulder, chuck and buttock and rump, formed a significantly (P < 0·01) lower percentage of the carcasses of the fattened than of the unfattened steers.