Tip of The Day - October 14, 2016

Photo by Tom Semadeni

First Snow

1988 Twinning in Beef Cattle

Paola de Rose, et al.

Embryos were collected non-surgically from donor cows. Recipients were either bred by artificial insemination (AI) and given one transferred embryo or received two embryos. Surgical and non-surgical transfers were performed using fresh and frozen embryos. Over four years, 114 donors yielded 671 embryos of which 351 were useful. A total of 303 embryos were placed in 187 recipients, of which 109 were previously bred using AI. Of 106 pregnancies, 60 produced single calves and 46 produced twins. Calves resulting from the breed and transfer (BT) method were blood typed to determine parentage.

Both total and useful numbers of embryos varied across years. Fresh embryo survival rate was 37% for 1981 and was different from rates in later years which averaged 25%. Fresh exceeded frozen embryo survival but the difference was not significant. There was no difference in embryo survival rates between the BT method and the transfer only (TO) methods. Pregnancy rates differed across years due to differences in transfer methods. Higher pregnancy rate (67%) was associated with the BT method, reflecting the success of AI. Pregnancy rate for the TO method was 43%. The mulptiple pregnancy rate average 24% and did not differ across years. Calf crop percent differed between transfer methods at 94% with BT and 65% with TO. The calf crop percent for BT was considerably better than TO or to first AI service.

Before the beef industry can exploit the potential for increased productivity and profitability associated with biparous cows, an effective, low cost method of inducing twin pregnancies must be perfected. Embryo survival rates must be increased if ET is to play a significant role in twin-induction.

Photo by Tom Semadeni