EFFECT OF PREPUBERTAL BODY-WEIGHT GAIN AND BREED ON CARCASS COMPOSITION AT PUBERTY IN BEEF HEIFERS

Fourteen prepubertal Angus heifers, all of which reached puberty, and 11 Santa Gertrudis (S G) heifers, eight of which reached puberty, were divided into two treatment groups. There was no breed difference in a ge at puberty for those that reached puberty. Treatment 1 (T1) heifers , fed to gain .5 kg/d, tended (P < .11) to be older than Treatment 2 ( T2) heifers, fed to gain 1 kg/d, at puberty. Body weight and height we re greater (P < .01) in SG than in Angus heifers at puberty. Angus hei fers in T2 deposited more fat over the rump during the 15 wk before pu berty, whereas Tl SG heifers deposited the least amount of fat (P < .0 5). Heifers in T2 were heavier at puberty (P < .05), had faster growin g longissimus muscle areas (P < .05), and deposited more fat over the rib (P < .01) as they approached puberty. The T2 (P < .05) and Angus ( P < .05) rib sections had more dissectible subcutaneous fat than did T l and SG rib sections. Angus heifers had higher marbling scores (P < . 0 5), as well as higher total lipid percentages for seam fat (P < .05) , longissimus muscle (P < .01), other lean tissue (P < .05), and subcu taneous fat (P < .01). Predicted total lipid content for the edible po rtion of the dressed carcass was higher for T2 heifers (P < .09).