Fat distribution in steer carcasses of different breeds and crosses. 1. Distribution between depots

Abstract

SUMMARY: Dissection data from 643 carcasses of castrated male cattle (steers) of 15 breed-type × feeding system groups were used to examine the distribution of total fat (TF) between subcutaneous (SF), intermuscular (IF), kidney knob and channel (KKCF) and cod fat depots. The breed-type groups, which were from cereal or grass/cereal feeding systems, included Ayrshire, Simmental × Ayrshire, British Friesian and Friesian crosses with Aberdeen Angus, Hereford, Limousin, Charolais, South Devon and Simmental. Means for percentage TF in side ranged from 21·4 to 36·2 with a pooled within group SD of 3·87.The growth of each depot relative to TF was examined using the allometric equation. Significant but not large differences existed between groups for the growth coefficients of SF and IF while the coefficients for KKCF differed widely among groups. The coefficient for SF was greater than that for IF in every group (pooled within-group b values±SE were 1·20±·02 and 0·87±0·01 respectively).At constant TF weight, carcasses from Ayrshire and Ayrshire crosses tended to contain less SF and more IF+KKC F than those from Friesian and beef breed × Friesian. Important differences in distribution were recorded between the various beef breed × Friesian groups. The proportion of SF was lower for cattle fed on grass/cereal diets than for cattle of the same breed type fed on cereal diets.The differences in fat distribution led to substantial bias for some groups when the percentages of IF and TF in the side were predicted from percentage SF. The bias was less when both KKCF and SF were used as predictors.