author(s)
AP Singh, VK Bhatt, Alok Kumar Singh and Pooja Singh

abstract
The experiment was conducted on 24 post partum crossbred cows at private dairy farm and divided into three treatment (TG) and control (C) group (6 each) were monitored for serum progesterone on 14^th,24^th,27^th,38^th, 41^st and 42^nd of post partum following GnRH and PGf₂α and in combination treatment TG-1 (GnRH - PGf₂α), TG-2 (GnRH –N.S), TG-3 (N.S - PGf₂α) and control (N.S – N.S) on day 14^th and 24^th with fixed timed artificial insemination by injecting PGf₂α on day 38^th in all the groups(except control) and reveals that mean serum concentration progestrone in TG-I,TG-II,TG-III and control1.74 ± 0.11, 1.72 ± 0.10, 1.70±0.09, 2.74±0.04 ng/ml. 4 in TG-I, 2 in TG-II,3 out of 6 treated cows in TG-III showed <1ng/ml progesterone concentration on day 41^st and 42^nd indicating that these animals exhibited oestrus and cyclity during the period of Fixed timed AI. Whereas none of the animals in control group showed <1ng/ml progesterone concentration on day 41^st and 42^nd indicating that these animals did not exhibit oestrus and cyclity during the period of Fixed timed AI. The data of mean serum progesterone concentration were also compared between and within treatment and control groups using Analysis of variance. There was a significant difference in serum progesterone concentration within and between the groups (P ≤ 0.01).