RESEARCHES REGARDING THE EFFECT OF PGF2α ADMINISTRATION INTERVAL ON COWS ESTROUS SYNCHRONIZATION

To improve reproductive efficiency of a dairy farm hormonal treatments for estrus synchronization are used. These allow heat and A.I. grouping to a specific time interval. In our experiments, we studied the estrous and A.I. grouping after the utilization of three hormonal synchronization programs. The protocols consisted of a single administration of PgF2a, to females with known estrous cycle and AI at 5 days interval, the other two protocols, applied to females with unknown estrous cycle, consisted of two doses of PgF2a, administered at 11 or 14 days interval respectively, and heat detection after the second dose administration. There were no significant differences (p>0.05), between the heat manifestation rates, to cows which were stimulated with two doses of PgF2a, at 11 days interval (85.7%), comparing to cows stimulated with two doses of PgF2a at 14 days interval (88.2%). Significant differences (p<0.05) were observed between the heat manifestation rates of cows to which was administrated a single dose of PgF2a (67.1%) and heat manifestation rates at females to which were administrated two doses of PgF2a (85.7-88.2%)