[Superovulation after administration of PMSG in cows of various breeds]

Abstract

Superovulation response was studied to i. m. administration of 2500 and 3000 i. u. of PMSG (special product Folligon, Intervet Co.) in 67 breeding cows of the Black-Pied Lowland. Slovak Pied and Slovak Pinzgau breeds within the 9th to 12th days of their sexual cycles. The time which had elapsed from these cows' last calving ranged from 50 to 150 days and the number of their prior calvings ranged from one to ten. The best superovulation effect was obtained after the administration of 2500 i. u. PMSG in the Pinzgau breed: these cows had, on the average, 13.20 +/- 2.36 corpora lutea without non-ovulated follicles. At the PMSG dose increased to 3000 i. u., the number of yellow bodies rose to 18.11 +/- 1.12 and that of non-ovulated follicles to 3.46 +/- 0.46. In the Slovak Pied breed the average number of yellow bodies obtained after administration of 2500 i. u. PMSG was 11.74 +/- 1.27 and that of non-ovulated follicles was 0.44 +/- 0.02. At the PMSG dose of 3000 i. u., the number of yellow bodies increased to 15.49 +/- 1.62 and that of non-ovulated follicles increased up to 5.12 +/- 0.81. In the Black-Pied Lowland breed the lowest response was obtained: the i. m. administration of 2500 i. u. PMSG resulted in the formation of 9.5 +/- 0.84 yellow bodies and 1.16 +/- 0.26 non-ovulated follicles, and at the dose of 3000 i. u. the respective numbers were 13.41 +/- 0.89 and 3.07 +/- 0.39. Comparing the superovulation effect in dependence on age, the response of the cows of the Black-Pied Lowland and Slovak Pinzgau breeds to PMSG administration increases until the age of nine years (from 9.79 and 13.6 yellow bodies, respectively, on the average for the first five years to 12.71 and 17.99, respectively, in the ninth year); in the Slovak Pinzgau breed it decreases from 15.83, recorded in the first five years, to 8.28 +/- 1.68 in the ninth year. The number of non-ovulated follicles grows with age in the Slovak Pinzgau breed from 3.46 +/- 0.46 in the first five years to 3.64 between five and nine years of age and up to 4.44 +/- 0.52 after the ninth year, in the Slovak Pied breed from 0.79 to 4.21 +/- 0.38, and in the Black-Pied Lowland breed from 2.69 to 3.20 +/- 0.22 between the fifth and ninth year.