This study was conducted to characterize the morphology and morphometry of follicles containing multiple oocytes (MOFs) and determine the association with the FecGE mutation in Santa Inês ewes. Based on the genotypes, 65 ewes were characterized as being homozygous wild-type (n = 25; FecG+/+), heterozygous mutant (n = 27, FecG+/E), and homozygous mutant (n = 13, FecGE/E). The variables evaluated were follicle developmental stage, number of oocytes per follicle, morphology, and morphometry of MOFs. The FecGE mutation did not affect the frequency of MOFs (P > 0.05) (3.0 % in FecG+/+; 3.3 % in FecG+/E; and 3.5 % in FecGE/E). The greater viability (P < 0.05) of MOFs was identified in transitory stage of the FecGE/E (95.0 %) and FecG+/E (90.9 %) when compared to the FecG+/+ genotype (73.3 %). Furthermore, the morphology of transitory follicles with two oocytes was the variable and when evaluated was the most reliable determinant for predicting which ewes had an FecGE mutation. In conclusion, the FecGE mutation did not affect the frequency of MOFs. The ewes with FecGE mutation had a greater frequency of morphologically normal MOFs in the transitory stage. Furthermore, the ewes with the FecGE mutation had a greater likelihood of having MOFs containing two morphologically normal oocytes.
Keywords: GDF-9; Multioocyte; Mutation; Ovine; Prolificacy.
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