Effect of hormonal therapies at breeding on plasma progesterone profile and fertility in repeat breeding holstein friesian cows

Twenty four repeat breeding HF cows with more than three infertile cycles were divided at random in 4 groups each of 6 animals with a view to study the relative efficacies of different hormonal therapies over control at breeding (GnRH 0.02 mg; LH/hCG 1500 IU; Progesterone 500 mg; all i/m) towards improving their reproductive efficiency together with the weekly profile of plasma progesterone, total protein, total cholesterol, triglycerides from the day of treatment up to 7 weeks post-treatment. The conception rates obtained within two cycles following 3 treatments were 66.66, 83.33 and 50.00%, respectively, with an overall mean of 66.66% (12/18) against 33.33% (2/6) in control untreated cows (P < 0.01). In GnRH, LH and progesterone treated and control groups, the pooled mean plasma progesterone concentrations averaged 3.42 ± 0.38, 5.19 ± 0.52, 4.03 ± 0.49 and 3.38 ± 0.41 ng/ml (P < 0.05), respectively, with an overall mean of 4.00 ± 0.23 ng/ml. The value in hCG treated cows was significantly (P < 0.05) higher as compared to control group. The mean P₄ levels in conceived and non-conceived groups were 5.68 ± 0.35 and 2.59 ± 0.23 ng/ml (P < 0.01). The overall weekly-pooled mean progesterone profile recorded from 0 to 7^th week post-oestrus/insemination was at basal level on day of oestrus, which increased significantly (P < 0.05) by 7^th day post-oestrus, fluctuated insignificantly till 7^th week with the peak value on 5^th week post-oestrus. The progesterone concentration in conceived group remained more or less at constant high level till 7^th week post-insemination, while in non-conceiving cows it showed peaks on 2^nd and 5^th week with drops on 3^rd and 6^th week. The progesterone level on day ‘7’ post-insemination was relatively lower in non-conceived cows as compared to conceived ones (2.99 ± 0.47 vs 4.78 ± 0.85 ng/ml), suggesting luteal deficiency.