"Fertility of dairy cows has been decreasing with a corresponding increase in milk productivity. Synchronization protocols using gonadotropin releasing hormone (GnRH) and prostaglandin F2 alpha (PG) have been designed to synchronize ovulation to allow timed artificial insemination (AI). To tackle challenges of lesser concentration of steroid hormones in higher producing cows, studies focused on increasing steroid hormones to imitate that of heifers have been reported. The objective of this thesis was to assess the effect of increased doses of final GnRH of Ovsynch in dairy cows on the LH peak and CL function [CL size and progesterone (P4) secretion]. Dairy cows (N=70) were enrolled in an Ovsynch protocol. Selected cows (n=24) were divided to receive three different doses of final GnRH (100 vs 200 vs 400 æg) of Ovsynch followed by timed artificial insemination (TAI). The LH peak and P4 per CL volume of the three treatment doses were not significantly different (p > 0.05) except for P4 per CL volume of 200 vs. 400 æg on day 7 (p =0.04). Similarly, in n=6 buffaloes, two doses (100 vs 400 æg) of final GnRH was used in Ovsynch. There was no significant difference in P4 per CL volume (p > 0.3) post treatment between the two treatment doses. Due to unforeseen shortcomings, our data is not adequate to conclude the effect of greater GnRH dose on CL function in cow and buffalo and we suggest further studies on GnRH doses in cow and buffalo synchronization protocols."--Page ii.
Read
