Semen evaluation of Murrah buffalo bulls using sperm functional tests

The aim of this experiment was to evaluate membrane integrity, vitality, and mitochondrial cytochemical activity, in frozen semen samples of buffalo bulls and compare those functions with the routine semen evaluation and field fertility. Twenty one frozen semen batches from 2 buffalo bulls were used for AI. For the semen evaluation, after thawing, an aliquot was evaluated for motility and vigor. An aliquot of each batch was used to evaluate the cytochemical activity using the 3-3’ diamino benzidine. Samples were scored in four classes according to the degree of midpiece staining, being class I showing midpiece totally stained, indicating full mitochondrial activity, and class IV showing no staining of the midpiece, indicating no mitochondrial activity. Two other aliquots were used for the hypo-osmotic swelling test (HOST) and the eosin nigrosin staining (VIT), to evaluate membrane integrity and vitality, respectively. Correlations were found between pregnancy rate and vitality and class II and III of the DAB staining (r=0.53, r=-0.39, and r=-0.38, respectively; p=0.05). No correlation was found for pregnancy rate and motility or vigor. Results indicate that functional tests may be an alternative to better predict the fertility of buffalo frozen semen samples