부산대학교 도서관

Fifteen spring-born Angus (AN) and 25 Brangus (BN) weanling heifers were used in a 2 × 5 factorial arrangement of treatments to evaluate the effects of breed and postweaning winter diet on heifer growth and development Dietary treatments were warm-season perennial grass hay (H), ammoniated H (AH), H plus .68 kg/d cottonseed meal (HP), H plus .45 kg/d cottonseed meal plus 1.37 kg/d ground corn (HPE) and HPE plus 200 mg/d monensin (HPEM). Mean initial weight and age for the 107-d feed trial were 207 kg and 270 d. Brangus had .06 kg greater (P< .05) ADG than AN during the trial. Although digestible DM intake (DDMT) relative to body weight was greater (P< .10) for AN than for BN, ADG:DDMI was greater (P< .05) for BN than for AN. Heifers fed H and AH lost weight, but heifers fed AH had 50% (P< .05) less daily weight loss than those fed H. Daily gain increased (P< .05) incrementally in response to sequential supplement additions of cottonseed meal (AH vs HP; -.10 vs .17 kg), ground com (HP vs HPE; .17 vs .29 kg) and monensin (HPE vs HPEM; .29 vs .39 kg). Hay DM intake relative to body weight and DDMI were increased (P< .01) by ammoniation. Intake did not differ between HPE and HPEM. Diet affected age at puberty (P < .05), which decreased with increased dietary components. Weight differences among diet groups following the winter feed trial were largely eliminated prior to breeding. Nevertheless, H- and AH-fed heifers collectively weighed less (P < .01) prior to breeding than did heifers of supplemented diet groups. Reproductive development tended to be adversely affected by weight loss during the postweaning period.