90 Comparing Methods of Raising Twin Beef Calves

Abstract Twinning has shown promise as a means of increasing reproductive efficiency in beef cattle. The objective of this study was to compare the performance of 1) twin calves raised by their dam (twin born-twin raised; TT); 2) twin calves where one calf was grafted to another cow that lost her calf and one calf was left with their dam (twin born-single raised; TS); and 3) single born calves that were raised by their dams (single born-single raised; S). To achieve twinning, sixty-three Angus-cross cows were estrus synchronized and artificially inseminated. Seven days later, an embryo was placed into the uterine horn contralateral to the corpus luteum. Fourteen twin pairs and 11 singleton calves were produced from the described technique. Three natural twin pairs were added to the study. Birth order was recorded for twin calves (1=first calf; 2=second calf). Birth weights (BW) and blood samples for measuring serum total protein, IgG1, and IgM were collected 24 h post-calving. Calves were weighed at approximately six months of age, and a 200-d adjusted weight was calculated using the following equation: [(ADG x 200 d) + BW=A200dW]. Calf behavior data collected included interval to standing and first nursing, duration of dam nursing, and duration of non-dam nursing. Single calves had greater (P < 0.001) BW compared to TT and TS. Adjusted 200-d weights were greater (P < 0.05) for S compared to TS. There was a positive correlation between BW and A200dW (r=.32; P < 0.05). Behavior data did not differ among raising methods. Twin-single calves had lower (P < 0.05) serum IgG1 concentrations compared to S calves. Twin-Twin calves had a combined A200dW of 185 kg more than single born-single raised calves.