Effectiveness of tes-tris or tris association with low density lipoprotein on in vitro longevity of refrigerated buffalo semen

ABSTRACT This study investigated in vitro the efficacy of four different extenders (TES-TRIS and TRIS with LDL low-density lipoprotein at concentrations of 10 or 5%) on the longevity of buffalo sperm in the refrigeration process at 5ºC. Sperm motility was assessed every 24 hours up to 72 hours of incubation using computer assisted sperm analysis and sperm membrane integrity was examined by the hypoosmotic test (HOST) at T1, T24, T48 and T72 hours. Eleven buffaloes (1 ejaculate per buffalo) of the Murrah breed were used, ranging in age from 4 to 5 years. Immediately after collection, each ejaculate was fractionated into 4 aliquots, and each aliquot was diluted in one of four diluents to obtain 50x106SPTZ/mL. The samples were packed in 0.5mL straws and refrigerated (-0.25°C/min) to 5°C and maintained at this temperature until evaluation. Prior to evaluation the samples were heated at 37°C for 30 seconds. The statistical package used for analysis was STATA 12.0 "Statistical Analysis Software" and means were compared by the Friedman test (P<0.05). The results of sperm kinetics and HOST indicate that the TRIS diluent with 10% LDL could be a promising alternative for semen refrigeration at 5ºC, to be used in conventional and fixed time artificial insemination.