Effectiveness of superovulation in heifers.
The aim of the study was to estimate the effectiveness of superovulation in heifers. Using multiple analysis statistically, examinations were carried out on 238 superovulated heifers, 11-56 months of age, of the Angus, Black-and-White × Holstein, Hereford, Charolais, Limousin and Piedmont breeds. The mean number of corpus luteum (NCL), total ova and embryos (TOE), total embryos (TE), menryos suitable for transfer (TRE) were respectively 7.52, 5.3, 4.05 and 3.08. Heifers superovulated with Foltropin-V had more TRE than those receiving Ovagen or Stimufol (3.49 to 2.89 and 3.19; P<0.05). The higher number of collections the higher NCL (P<0.01), TOE (P<0.001), TE (P<0.00005), TRE (P<0.001) and DEG (P<0.01). An important influence on superovulation results was the herd of origin of the cows. More NCL was ascertained in summer (P<0.05), nevertheless in atumn a higher number of degenerated embryos was noted. The breed of heifers only had an influence on the number of corpus luteum. Heifers of the Limousin and Black-and-White × Holstein breed had more corpus luteum than Piedmont. The higher the share of the blood of Holstein was in the blood of Black-and-White heifers, the higher was the number of embryos (P<0.001), embryos suitable for transfer (P<0.001) and degenerated embryos (P<0.001). There was no effect of the age of the heifers or bulls on effectiveness of superovulation, the number of embryos and embryos suitable for transfer, however bulls had a marginal influence on the proportion of TRE/TE (P<0.06).