REPRODUCTIVE-PERFORMANCE, CALF GROWTH, AND MILK-PRODUCTION OF FIRST-CALF HEIFERS SIRED BY 7 BREEDS AND RAISED ON DIFFERENT LEVELS OF NUTRITION

We evaluated heifers crossbred from seven breeds of sires (Hereford, A ngus, Belgian Blue, Piedmontese, Brahman, Boran, and Tuli) and three b reeds of dams (Angus, Hereford, and MARK III [four-breed composite]). Heifers were mated to Red Poll sires to calve at 2 yr of age. Heifers were placed in two treatments from weaning to breeding and raised on a high nutrition level(15.8 Meal ME/d) or on 80% of the high nutrition level (12.6 Meal ME/d). Breeds differed in the age of the heifers at p arturition (P = .03). Birth weights of calves differed by maternal gra ndsire (P < .001) but not by heifer treatment (P = .91) or maternal gr andam (P = .19). Heifers differed in their postpartum interval to estr us by sire breed (P .001). Calf age at weaning (P = .02), calf ADG (P < .001), and 205-d weight (P < .001) differed between breeds of matern al grandsires. Milk production from 50 to 200 d of lactation was great est for heifers of Belgian Blue (1,070 +/- 30 kg) and Brahman (1,029 /- 38 kg) sires. Milk production did not differ with treatment group ( P = .84). This study suggests that over a diverse group of breeds, acc elerated rates of gain during the postweaning period within the ranges of this study do not result in increased production efficiency of the cows.