title: Reproductive performance, calf growth, and milk production of first-calf heifers sired by seven breeds and raised on different levels of nutrition.
abstract: We evaluated heifers crossbred from seven breeds of sires (Hereford, Angus, Belgian Blue, Piedmontese, Brahman, Boran, and Tuli) and three breeds of dams (Angus, Hereford, and MARC 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 Mcal ME/d) or on 80% of the high nutrition level (12.6 Mcal ME/d). Breeds differed in the age of the heifers at parturition (P = .03). Birth weights of calves differed by maternal grandsire (P < .001) but not by heifer treatment (P = .91) or maternal grandam (P = .19). Heifers differed in their postpartum interval to estrus 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 maternal grandsires. Milk production from 50 to 200 d of lactation was greatest 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, accelerated rates of gain during the postweaning period within the ranges of this study do not result in increased production efficiency of the cows.
authors.affiliation: USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933, USA.
authors.forename: H C
authors.initials: HC
authors.lastname: Freetly
authors.forename: L V
authors.initials: LV
authors.lastname: Cundiff
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001724:Birth Weight / Q000235:genetics / Q000502:physiology; D001947:Breeding; D002417:Cattle / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003433:Crosses, Genetic; D002149:Energy Intake; D004971:Estrus / Q000235:genetics / Q000502:physiology; D005260:Female; D005298:Fertility / Q000235:genetics / Q000502:physiology; D007774:Lactation / Q000235:genetics / Q000502:physiology*; D016018:Least-Squares Analysis; D008297:Male; D011897:Random Allocation; D012098:Reproduction / Q000235:genetics / Q000502:physiology*; D012741:Sexual Maturation / Q000235:genetics / Q000502:physiology; D014886:Weaning; D015430:Weight Gain / Q000235:genetics / Q000502:physiology