|Echternkamp, Sherrill -|
|Gregory, Keith - FORMER ARS EMPLOYEE|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 30, 2001
Publication Date: July 1, 2001
Citation: Echternkamp, S.E., Gregory, K.E. 2001. Reproductive, growth, feedlot, and carcass traits of twin versus single births in cattle [abstract]. Journal of Animal Science Supplement. 79 (Supplement 1):207. Technical Abstract: Fraternal twin calves presents a new paradigm in beef cattle management and production and affords an opportunity to increase both reproductive and economic efficiency. Breeding value for twinning was predicted by repeated measures of ovulation rate in yearling heifers and of twinning rate. Twinning rate increased 3% per year to an annual rate of 50 to 55%. Gestation length was shorter (275.6 vs 281.3 d; P<0.01) and birth wt was smaller (38.2 vs 47.0 kg; P<0.01) for twin vs single calves, respectively, but total birth wt (live) was increased 53.1% for twins. Respective weaning wt (200-d wt) were 232 vs 259 kg (P<0.01). Number of calves weaned per cow calving was 0.92 for single vs 1.52 for twin births (P<0.01) or a 58.4% increased total weaning wt for twins. Single male calves gained 74 g more per d than twin males from birth to 200 d, and 45 g more per d from 200 d to slaughter. Carcass traits were similar for twin and single males. Freemartins, 96% of the females born co-twin to a male, did not differ from normal females in growth traits, but freemartins had higher (P<0.05) marbling scores. Constraints of twins were increased (P<0.01) incidence of retained placentae (28.0% vs 1.9%), dystocia (46.9% vs 20.6%) and perinatal calf mortality (16.5% vs 3.5%). Dystocia of twins resulted from malpresentation of one or both calves. Fertility was reduced 11.6% (P<0.01) after a twin birth but varied significantly (P<0.01) among years and seasons. Overall, twinning increased productivity at weaning by 54.2 kg or 28.3% per cow exposed at breeding.