Data on 1390 Zebu donors multiple ovulation followed by embryo transfer results were analyzed. The donors came from different regions of Brazil and belonged to Brahman (31), Gir (22), Guzerá (68) and Nelore (411) breeds. The age of donors ranged from 1.5 to 19.5 years old. The first recovery data and consecutive recovery data were submitted to multivariate analysis. The estimated Pearson correlation coefficients were: 0.72 between total recovered structures (ER) and number of viable embryos (EV); 0.66 between ER and total of positive pregnant receptors (PP); 0.53 between ER and number of palpated corpora luteum; 0.89 between EV and PP; 0.33 between EV and CL and 0.30 between PP and CL. Relationships among inbreeding coefficient, age of donors to superovulation, stimulating drug, drug dosage, recovery number and number of executed insemination were also observed. Factor analysis indicated the following factors for consecutive recoveries: factor 1 - factors that reduce superovulation response, factor 2 - superovulation scheme according to characteristics of donors, factor 3 - success of superovulation scheme. For first recovery analysis the following factors were designated: factor 1 - optimum age for superovulation, factor 2 - superovulation scheme according to characteristics of donors, and factor 3 - alternative superovulation scheme. The analysis also indicated the results of superovulation are quite variable and that the age of donors to superovulation, inbreeding coefficient of donors, recovery number, drug dosage and number of inseminations have high effect on the results. The number of viable embryos and the correlation between number of viable embryos and total of positive pregnant receptors can be indicators of MOET success.
Zebu cattle; multiple ovulation; embryo transfer; multivariate analysis
