Dietary effects on beef composition: II. Quantity and distribution of fat

Abstract

Studies were conducted on the quantity and distribution of fat in 104 half-sib Angus steers which had received various combinations of hay, corn silage, and corn concentrate. Groups were slaughtered at live weights of 216, 284, 340, 409, and 454 kg. The weights of mesenteric, cod, pelvic, kidney and total excess carcass fat were determined. Four linear measurements of subcutaneous fat, three cross-sectional area measurements of intermuscular fat, and the intramuscular fat in seven muscles were observed. The results showed that the feeding regimes had marked influences on the quantity and location of fat, particularly during the early feeding period (216-340 kg live wt.). Feeding hay during this period generally resulted in less fat deposition than feeding corn silage, but the suppression of intramuscular fat deposition was not evident until the animals were subsequently fed higher energy rations to heavier weights (409 and 454 kg). The results indicated that it may be possible to design dietary regimens that suppress waste fat but allow intramuscular fat to be deposited.The results described above imply that one might influence the deposition of intramuscular fat by proper design of the diet in the early feeding period. Although this possibility exists, it is noted that quantities of chemically extractable fat are not identical with quantities of marbling fat and hence changes in the former may not alter the visible quality of the meat.