Buffaloes (Bubalus bubalis) sperm cooling face to different extenders and evaluation of sperm in casa motility

The objective of this experiment was to test the in vitro efficacy of different extenders: TES and TRIS (Brito, 2014) with LDL (low density lipoproteins) concentrations of 10 and 5% on sperm longevity of buffalo in the cooling process at 5oC. We used 3 ejaculates from 4 male Murrah buffaloes, used to semen collection with artificial vagina. After collection, each sample was subjected to analysis of the physical and morphological characteristics of semen (CBRA, 2013). Immediately after collection, each ejaculate was split into four aliquots, each sample being diluted in extensors to obtain 50x106 SPTZ/mL. The filling was performed in 0.5mL straws, packed in a plastic bag (chupchup) containing metal balls on the bottom and attached to the edge of a glass container, submerged in a container with water at 27°C. The flask was placed in an environment at 5°C, obtaining a cooling curve of 0.25oC/minute. The semen straws were kept in active cooling (counter refrigerator) at 5°C and sequentially evaluated, reheating the contents at 37°C 30 seconds before the evaluation of sperm motility (total and progressive), using the computerized system (CASA), in times of 12, 24, 48, 72 and 96 hours, with the evaluations of T0 being made subjectively. Data were analyzed by Anova (split plot) and t test (P < 0.05), using the Assistat software 7.7 beta (2016). The average total motility (%) found after cooling regarding the extensor TES 10%, TES 5%, TRIS 10% and TRIS 5% were 68.0a, 66.6b, 63.9c, 63.7c; and for times 12, 24, 48, 72 and 96 hours 91.3a, 81.8b, 70.5c, 55.9d and 28.4e, respectively. The averages of progressive motility (%) were 44.2a, 43.2a, 41.5b 41.9b regarding the extenders mentioned above; and the times were 68.4a, 53.5b, 42.4c, 30.9d and 18.1e respectively. Interactions between extender and storage times were not significant for the variables studied. It is concluded that the TES 10% LDL was the best extender in the in vitro preservation of sperm during cooling. The results allow to incorporate the use of semen cooled up to 48 hours, as a management option in the fertilization of buffalo females, to reduce costs and improve reproductive efficiency of TAI programs. However, the research should be continued in order to identify suitable extenders for a greater efficiency of this technique.