title: Differences among breed crosses of cattle in the conversion of food energy to calf weight during the preweaning interval.
abstract: The objective of this study was to determine whether F1 cows that differ in genetic potential for weight at maturity and milk yield vary in the conversion of food energy to calf weight gain. Food intakes and weight change data were recorded by pen for cows and calves from approximately 45 d postpartum. Cows assigned to the study were 7- to 9-yr-old F1s produced by top-crossing Angus, Hereford, Brown Swiss, Chianina, Gelbvieh; Maine Anjou, and Red Poll sires to either Angus or Hereford dams. Calves were sired by Simmentals. Experimental units were pens (10 to 12 cow/calf pairs); pen was replicated within breed of sire in each of 2 yr (n = 24). Calf weight gain and energy consumed by the dams differed among the F1s, as did the ratio of calf weight gain to energy consumed by the calf and cow. Angus or Hereford (35.8), Red Poll (35.7), or Maine Anjou (35.6) F1s produced more calf weight per unit of energy consumed (g/Mcal) by the cow and calf than Chianina (33.1) or Gelbvieh (33.7) F1 females; Brown Swiss cows were intermediate (34.3). Differences in food conversion efficiency exist among breed crosses. These differences seem to be associated with breed cross differences in genetic potential for milk yield and mature weight; an exception to this trend was the Maine Anjou.
authors.affiliation: USDA, Roman L. Hruska U.S. Meat Anim. Res. Center, Clay Center, NE 68933-0166.
authors.forename: T G
authors.initials: TG
authors.lastname: Jenkins
authors.forename: L V
authors.initials: LV
authors.lastname: Cundiff
authors.forename: C L
authors.initials: CL
authors.lastname: Ferrell
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001724:Birth Weight; D001947:Breeding; D002417:Cattle / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003433:Crosses, Genetic; D004435:Eating; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D007774:Lactation / Q000235:genetics / Q000502:physiology*; D012044:Regression Analysis; D015430:Weight Gain