Effect of Using Low Doses of PGF2α and GnRH Hormones on Reproduction of Dairy Cows

Abstract

The research aims to improve reproductive performance of repeat breeder or anestrous cows using PGF2 α and GnRH through in intra vulva injection. In this study, 30 Friesian dairy cows were not conceiving for a period ranging from 120 to 250 days after calving. Cows divided into three groups, 10 cows in each group and were subjected to the following protocols. Group1 (G1): was injected with 50 μg GnRH on Day 0 and 5 mg PGF2α on Day 7 then the oestrus cycle was monitored. Group 2 (G2): cows were injected twice 5 mg PGF2α, 11 days apart. Group 3 (G3): was injected with 50 μg GnRH at Day 0, 5 mg PGF2α, at Day 7 and then injected with 50 μg GnRH at day 9 and fixed timed artificial insemination (TAI) was performed 16 to 18 h. The results showed that, exhibited oestrus 100, 90 and 80% in G3, G2 and G1, respectively. Pregnancy rates were significantly highest in G3 and G2 than in G1. The progesterone (P4) concentration on day 24 post-insemination was 10.253, 11.235 and 11.567 ng/ml in pregnant versus were 3.245, 1.985 and 2.036 ng/ml in non- pregnant cows in G1, G2 and G3, respectively. Progesterone concentration at 2nd GnRH or PGF2α injections were significantly lower in pregnant cows than in non-pregnant cows in G1, G2 and G3 groups. The economic evaluation was shown that 2 PGF2α protocols had the cheapest cost (L.E 21/animal) highest pregnant cows.