RESUMEN
The study was designed with the objective of expression analysis of pro-apoptotic BAX and anti-apoptotic BCL-2 genes on lactation performance in Bos indicus and HF crossbred cows during early lactation. BAX/BCL-2 mRNA expression ratio in HF crossbreds showed a steady increase from 30th day to 90th day, but in Deoni cows the ratio exhibited a different pattern, which increased from day 30 to day 60, decreased on day 75, and then increased on day 90. BAX/BCL-2 expression ratio in Deoni and HF crossbreds were lowest on day 30 and highest on day 90. On contrary, the milk yield was highest on day 30 and lowest on day 90 suggesting BCL-2 gene favors milk production and BAX gene oppose milk production. In comparison to HF crossbreds, Deoni cows exhibited highest BAX/BCL-2 ratio at the end of early lactation, indicating Bos indicus cows were more sensitive to apoptosis than HF crossbreds. Comparison of daily milk yield with BAX/BCL-2 mRNA expression ratio revealed significant negative correlation with a correlation coefficient of -0.98 (P < 0.01) and -0.95 (P < 0.05) in Deoni and HF crossbred cows, respectively. Our study provides new insights into understanding the genetic control of mammary apoptosis between Bos indicus and HF crossbreds.