Milk and serum progesterone assay for evaluation of reproductive performance of dairy herds in Thailand

Cross-bred dairy cows (n=202) were used to study the milk progesterone profiles 0, 5, 7, 12, 20, 28, 35 and 45 days after artificial insemination. It was found that 57% (115/202) of the cows had a normal oestrous cycle and conceived, but in 13% (15/115) of cows that conceived the embryos died between 28 and 35 days of gestation. A total of 43% (87/202) of the cows did not become pregnant and these could be classified into four groups: 15% (31/202) had normal oestrous cycles; 7% (15/202) were inseminated during the luteal phase, i.e. when progesterone concentrations were elevated; 14% (29/202) had irregular cycles; and 6% (12/202) were acyclic. In another study milk samples were collected every 3 days from 90 cross-bred dairy cows, commencing 15 days after parturition and continuing until each animal had been inseminated. The milk progesterone profiles of each cow were collated with the records of oestrus and insemination. The average post-partum anoestrous periods of primiparous and multiparous cows were 35.0 ± 16.4 and 34.9 ± 14.5 days, respectively. In 68% of the primiparous cows and 65% of the multiparous cows oestrus occurred between days 20 and 40 of the post-partum period. Sequential serum samples from 42 repeat breeder cows and 8 infertile heifers were analysed for progesterone, and their ovaries were examined weekly by rectal palpation. They were treated with either human chorionic gonadotrophin (HCG), pregnant mare serum gonadotrophin (PMSG) or prostaglandin F2α. As a result, 23 cows and 5 heifers re-established oestrous cycles and became pregnant after AI. Progesterone profiles and rectal palpation revealed various causes of infertility, including ovarian cysts, irregular oestrous cycles, inactive ovaries and abnormal oviducts. Fifty-six per cent of repeat breeder cows and infertile heifers responded to hormone treatment in terms of resumed ovarian function. (author). 14 refs, 6 figs, 3 tabs