Influence of frame size and body condition score on performance of Brahmancattle

The effects of frame size (FS) and body condition score (BCS) on performanc e of Brahman cows were evaluated using records collected from 1984 to 1994 at the Subtropical Agricultural Research Station, Brooksville, Florida. Age at puberty (AP), calving rate (CR), calving date (CD), survival rate (SR), weaning rate (WR), birth weight (BWT), weaning weight (WWT), preweaning AD G, and kilograms of calf produced per cow exposed (PPC) were obtained from first- (n = 215), second- (n = 130), and third or greater-parity (n = 267) dams. Based on hip height at 18 mo of age, heifers were assigned to three F S groups: small (115 to 126 cm), medium (127 to 133 cm), or large (134 to 1 45 cm). Small and medium FS heifers attained puberty at younger (P < .05) a ges (633.2 +/- 12.3 and 626.4 +/- 12.0 d) than large FS heifers (672.3 +/- 17.1 d). Calving rate in large FS second-parity dams was 27% less (P < .05) than in small and medium FS dams. In third or greater-parity dams, CR was greater (P < .05) for small FS cows than for medium and large FS cows. Acro ss the three parity groups, CR improved with increasing BCS. Except for the first-parity dame, animals with better fall BCS calved earlier (P < .05). In first-parity dams, SR was less (P < .01) in large (47.9 +/- 11.0%) than in small (80.7 +/- 5.2%) and medium (83.4 +/- 4.7%) FS groups. Weaning rate s of large FS first- and second-parity dams were less (P < .05) than those of small and medium FS dams. Second-parity dams with BCS 3 had lower (P < . 05) WR than dams with BCS 4 and 5. Within first- and third or greater-parit y dame, BWT of calves born to small FS cows were the lightest, and those bo rn to large FS dams were the heaviest; those born to medium FS dams were in termediate (P < .05). In second-parity darns, BWT of calves of large FS dam s were greater (P < .05) than those of small and medium FS dams, In first-p arity dams, calves weaned by small FS cows had lower (P < .05) WWT than tho se weaned by higher FS cows. In the third or greater-parity group, large FS dams weaned heavier calves (P < .05) than other dams. In all parity groups of dams, calves out of large FS cows had greater ADG (P < .05) than those from small and medium FS cows. In first-parity dams, PPC was comparable bet ween small and medium FS dams, but both tended to be greater (P < .10) than PPC of large FS dams. Small and medium FS females reached puberty at an ea rlier age, calved earlier, and had greater calving, survival, and weaning r ates, as well as greater kilograms of calf produced per cow exposed than th e large FS females. As the large FS cows matured, they seemed to have overc ome the negative effects imposed by FS that were observed at younger ages. Their performance traits were generally all comparable to those of smaller cows once they had reached maturity.