title: Output/input differences among nonpregnant, lactating Bos indicus-Bos taurus and Bos taurus-Bos taurus F1 cross cows.
abstract: Nonpregnant F1 crossbred cows, progeny of either Hereford (H) or Angus (A) dams and sired by Brahman (Bm), Sahiwal (Sw), Pinzgauer (Pz), H, or A sires, were fed to maintain initial weight while rearing Charolais (C)-sired progeny for a period of 126 d in drylot commencing at about 48 d postpartum. Cow-calf pairs were assigned to equalize cow age, calf sex, and breed of cow's dam among three replicate pens of approximately 12 pairs each. Cows and calves were weighed every 2 wk and feed intake was adjusted to minimize change in cow weight. Metabolizable energy (ME) consumption for zero cow weight change was estimated by regression. Milk production was estimated by weight-suckle-weigh at 58, 85, 125, and 170 d of lactation. Calf gain (GAIN, kg) relative to cow weight (CWT1, kg) was higher (P less than .01) for calves from Bm-X (139.5/585) and Sw-X (132.2/534) than for calves from Pz-X (127.2/552) and HA-X (116.9/547) cows. Estimated mean daily production of milk was 7.40, 7.15, 7.28, and 6.37 kg for the Bm-X, Sw-X, Pz-X, and HA-X, respectively. Total cow ME intake (TMEcow) for breed groups ranked (P less than .05) with cow size and milk production, and calf creep-feed intake (FMEcalf) was inversely related to estimated milk intake. Proportion of total feed ME (TMEcow+calf) consumed by calves was higher (P less than .05) for HA-X cows (18%) than for the others (14%). Total efficiency of calf gain in weight (GAIN/TMEcow+calf) was 11% greater (P less than .05) for crossbred cows of Bos indicus X Bos taurus (Bm-X, Sw-X) than for Bos taurus X Bos taurus (Pz-X, HA-X) cows (35 vs 32 g/Mcal) in the 126-d lactation period.
authors.affiliation: U.S. Department of Agriculture, Clay Center, NE 68933.
authors.forename: R D
authors.initials: RD
authors.lastname: Green
authors.forename: L V
authors.initials: LV
authors.lastname: Cundiff
authors.forename: G E
authors.initials: GE
authors.lastname: Dickerson
authors.forename: T G
authors.initials: TG
authors.lastname: Jenkins
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000704:Analysis of Variance; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001724:Birth Weight / Q000235:genetics; D001947:Breeding; D002417:Cattle / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D003433:Crosses, Genetic; D004435:Eating; D002149:Energy Intake; D005260:Female; D007774:Lactation / Q000502:physiology*; D009752:Nutritional Status; D015430:Weight Gain