title: Effects of twinning on dystocia, calf survival, calf growth, carcass traits, and cow productivity.
abstract: This paper reports results from a long-term experiment with a primary objective to increase twinning rate in cattle at the Roman L. Hruska U.S. Meat Animal Research Center. Survival of singles was 13% higher (P < .01) than that of twins at birth, and the difference in survival in favor of singles was of similar magnitude at 72 h (12.9%, P < .01), 150 d (14.8%, P < .01), and 200 d (15.2%, P < .01). Survival of calves with no dystocia was higher than survival of calves with dystocia: 8.6% (P < .01) at birth, 10.8% (P < .01) at 72 h, 12% (P < .01) at 150 d, and 12.2% (P < .01) at 200 d. The effect of dystocia on survival was greater (P < .01) in twins than in singles at birth and at 72 h. Least squares means for dystocia were 20.4% in singles compared with 42.2% in twins. Most of the dystocia in singles resulted from a traction requirement (84.7%) of normal presentations, whereas most of the dystocia in twins (77.8%) resulted from malpresentations, with 59.2% of the malpresentations accompanied with a requirement for traction. Survival in singles ranged from 10.7% to 15.3% greater than in twins at different ages when there was no requirement for assistance in either singles or twins. Calves born as singles were 8.8 kg heavier (P < .01) at birth and 28 kg heavier (P < .01) at 200 d than calves born and reared as twins. Calf weight produced per cow calving was 53.1%, 54.7%, and 58.4% greater (P < .01) at birth, 150 d, and 200 d, respectively, in cows producing twins than in cows producing singles. Cows producing twins had 65.2% more (P < .01) live calves at 200 d than cows producing singles. Single male calves gained 74 g more per day than twin males from birth to 200 d, 45 g more (P < .01) per day from 200 d to slaughter and 57 g more (P < .01) per day from birth to slaughter. Differences between twin and single males in carcass traits were small. A sample of steers from the Twinning Project gained significantly faster and produced significantly more desirable carcasses than a sample of steers from a high performance reference population. Freemartins did not differ (P < .05) from normal females in growth traits, but freemartins had higher (P < .05) scores for marbling with a higher percentage (P < .05) of USDA Choice or better quality grade carcasses and lower estimated percentage retail product.
authors.affiliation: Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Gregory
authors.forename: S E
authors.initials: SE
authors.lastname: Echternkamp
authors.forename: L V
authors.initials: LV
authors.lastname: Cundiff
mesh_terms: D000704:Analysis of Variance; D000822:Animal Husbandry; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000502:physiology*; D001724:Birth Weight / Q000502:physiology; D001823:Body Composition / Q000502:physiology*; D001947:Breeding / Q000379:methods; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D004420:Dystocia / Q000503:physiopathology / Q000662:veterinary*; D005260:Female; D005298:Fertility / Q000502:physiology*; D005328:Fetal Viability; D005611:Freemartinism / Q000503:physiopathology; D008297:Male; D008423:Maternal Age; D008460:Meat / Q000592:standards; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple / Q000502:physiology*; D012098:Reproduction; D012621:Seasons; D014427:Twins; D014481:United States; D016885:United States Department of Agriculture; D015430:Weight Gain / Q000502:physiology