|Gregory, Keith - FORMER ARS EMPLOYEE|
Submitted to: Journal of Animal Science
Publication Type: Review Article
Publication Acceptance Date: January 25, 2002
Publication Date: March 1, 2002
Citation: Echternkamp, S.E., Gregory, K.E. 2002. Reproductive, growth, feedlot, and carcass traits of twin versus single births in cattle. Journal of Animal Science. 80 (E Supplement 2):E64-E73. Technical Abstract: Annual frequency of fraternal twins increased 3.1% per year to 50 to 55% in a selected herd of cattle at the U. S. Meat Animal Research Center. Because twin ovulations are the first prerequisite for fraternal twins, breeding value for twinning was predicted by repeated measures of ovulation rate in yearling heifers and of twinning rate in selected females. Gestation length was shorter (276.1 vs 283.1 d; P < 0.01) and birth weight was smaller (37.2 vs 47.2 kg; P < 0.01) for twin vs single calves, respectively; total birth weight was increased 53.1% for twins. Respective 200-d weaning weights were 232 vs 259 kg (P < 0.01). Number of calves weaned per cow calving was 0.89 for singles, 1.52 for twins, and 1.80 for triplets (P < 0.01); total weaning weight was increased 48.1% for twin and 66.8% for triplet births. Single-born male calves gained 74 g more per d than twin-born males from birth to 200 d, and 45 g more per d from 200 d to oslaughter. Differences in carcass traits between twin and single steers were small. Freemartins, 96% of females born co-twin to a male, did not differ from intact twin females in growth traits, but freemartin carcasses had greater (P < 0.05) scores for marbling and USDA quality grade. Efficiency constraints to twin births were increased (P < 0.01) incidence of retained placentas (27.9% vs 1.9%), dystocia (46.9% vs 20.6%) and perinatal calf mortality (14.1% vs 3.6%). Dystocia of twins resulted primarily from malpresentation of one or both calves. Fertility was reduced 11.6% (P < 0.01) after a twin birth and 7.3% (P < 0.05) after a retained placenta, but the effect of twinning on fertility varied (P < 0.01) among years and seasons. Collectively, twinning increased productivity at weaning by 54.2 kg (or 28.3%) per cow exposed at breeding.