Regresar

Evaluation of the Reproductive Performance of Cross-Bred Zebu Cattle under Artificial Insemination Through the Use of Progesterone Radioimmunoassay in Venezuela

Abstract:

A survey was carried out to evaluate the reproductive performance of cross-bred zebu cattle under Artificial Insemination through the use of Progesterone-Radioimmunoassay in defatted milk samples taken at the moment of Al, 10 days and 22 days postservice and at pregnancy diagnosis. Six farms in the western region of Venezuela were involved in this work and a total of 600 Al were studied. The calving to first service and to conception interval showed no significative differences between the hand (suckling) and machine milk system (non suckling). However significant differences (P<0.05) were found among farms within the traditional and hand milk system. Comparison of first calving heifers with second or more calving cows were 141.9±6.9; 71.8±4.2 and 154±8.9; 80.8±5.5 days for the calving to first service and calving to conception interval respectively (P<0.05). Season of calving, dry vs rainy, were 115.4±5.2; 98.3±5.5 and 123.8±6.8; 111.1±7.2 for the first service and the conception interval respectively (P<0.05). Predominant Bos indicus cows had shorter intervals (P<0.05) to the first service and to the conception than predominant Bos taurus cows. Predominant breed and parity showed significant differences in overall conception rate analyzed by Chi-square analysis. Correct heat detection was determined by low P4 levels at Al, showing the best farm 95.5% and the worse farm 83.3%. The result of this study identifies a postpartum anestrus problem especially in the first calf heifers with an important effect of season, breed, farm, and heat detection on the reproductive efficiency of farms under Al.