Effects of Age and Season on in vivo Embryo Production of Friesian Holstein Cows

Embryo transfer is one of the leading technologies that is now being applied in an effort to increase the population and productivity of dairy cattle in Indonesia. Several factors may affect embryo production including age and season. In this study, the effects of age and season on in vivo embryo production were evaluated on Friesian Holstein (FH) cows. A total of 74 embryo production records from 10 FH cows aged 25-120 months were included in this study. The age of FH cows was divided into four categories, namely 25-48, 49-72, 73-96 and 97-120 months. The factor of season was divided into two categories, namely rainy (October-April) and dry (May-September). The variables observed were the number of corpus luteum, total embryo/ova, transferable embryo, degenerative cells, and nonfertilized oocytes. The results showed that the corpus luteum, total embryo/ova, and degenerative cells were not affected by age. However, the age significantly affected transferable embryos and nonfertilized oocytes, with the optimum range of age 49-72 months for transferable embryos. On the other hand, the season had no significant effect on all embryo production parameters. It could be concluded that age is a significant determinant for in vivo embryo production of FH cows. Meanwhile, the different seasons do not alter embryo production, which indicates that embryo collection can be performed throughout the year.