The effect of hormonal stimulation on the follicle population in the ovaries of ewes during estrus and anestrus

In the oestral and anoestral periods, 129 ewes of the Slovak Merino breed were treated with different doses of the stimulants PMSG, PGF2 alpha, HCG, SG and FSH after synchronization by means of Ageline tampons. In the anoestral period, PMSG doses of 750 and 1000 i. u. were found to increase the number of tertiary follicles from 12.3 to 17.2 and 18.6, whereas the dose of 1500 i. u. was found to reduce this number from 18.6 to 13.5. PGF2 alpha increases the average number of tertiary follicles from 12.3 to 22.2 and when it is combined with 750 i. u. PMSG, the increase is to 29.3 tertiary follicles. At higher PMSG doses the ratio of atretic (A) to non-atretic (N) tertiary follicles rose and the number of ovulations increased from 2.5 to 4.0. After synchronization with Ageline and administration of PMSG at the doses of 750 and 1000 i. u., the number of tertiary follicles increased from 16.0 to 18.4 and the number of ovulations from 3.1 to 5.7; the number of atretic tertiary follicles showed no change. In the oestral period, the dose of 1000 i. u. PMSG administered after PGF2 alpha reduced the number of tertiary follicles from 18.9 to 14.5 and increased the number of ovulation from 1.6 to 2.6; an increase was also recorded in the number of atretic tertiary follicles.(ABSTRACT TRUNCATED AT 250 WORDS)