Artificial insemination and fixed-time embryo transfer in beef cattle under dry tropical conditions

Gestation percentage was assessed after fixed time embryo transfer (FTET) and artificial insemination (FTAI) programs as a means to evaluate its use to improve reproductive efficiency in beef herds in Tamaulipas, under dry tropic conditions. Two FTET programas were conducted the north part of the state, the first, at the ranch Puesta de Sol (Burgos), where 30 beef crossbred heifers were treated with CIDR plus estradiol benzoate and cipionate for FTET; the second was conducted at the ranch La India (Reynosa), where 95 beef crossbred heifers using the same treatment. Embryos from Beefmaster donors were produced at the Laboratorio FIV of UGRT and transferred fresh, to 23 heifers at Puesta de Sol and 77 heifers at La India, where 8 and 32 gestations were obtained, for 35 and 42%, respectively, for a total gestation rate of 40%. The FTAI program was conducted at the ranch San Isidro (Guémez), where 133 registered Red Brangus (50 cows) and Charolaise (88 cows) were treated with the protocol described for FTET, plus an injection of 330 IU of eCG to nursing cows and cows in poor body condition. A total gestation rate of 41% was obtained, gestation rate was greater for Red Brangus (50%) than for Charolaise (35%) cows; partial gestation rates were 34 and 24% and 23 and 16%, respectively for both programs and breeds. Differences for both FTET and FTAI programs were not significant. Results obtained in this study allow recommending the use of such biotechnological tools to improve reproductive efficiency in beef herds in Tamaulipas.