Use of distinct cryoprotectant solutions in extenders for frozen ram semen

Em ovinos, as baixas taxas de prenhez obtidas com insemina????o artificial com s??men congelado inviabilizam o seu uso como rotina. Provocando o processo de criopreserva????o les??es nos espermatoz??ides, o desenvolvimento de diluentes que incluam crioprotetores de excel??ncia se justifica. Este trabalho testou a inclus??o da lipoprote??na de baixa densidade (LDL) e da trealose em diluentes para congelamento de s??men ovino, a partir da avalia????o de par??metros de qualidade seminal p??s-descongelamento. No primeiro experimento, foram comparados 3 tratamentos: Tris com 20% de gema de ovo e 5% de glicerol (T1); Tris com 100 mM de trealose (T2); e T1 com 50 mM de trealose (T3). A motilidade n??o diferiu entre os tratamentos (P > 0,05), mas o T2 apresentou maior propor????o de gametas com membranas ??ntegras (P < 0,05). No segundo experimento, foram comparados 4 tratamentos: Tris com 20% de gema de ovo (T1); T1 com 5% de glicerol (T2); T1 com 100 mM de trealose (T3); e T1 com 100 mM de trealose e 5% de glicerol (T4). A motilidade e a integridade da membrana esperm??tica do T2, T3 e T4 foram superiores a do T1 (P > 0,05), mas a integridade do acrossoma n??o diferiu (P > 0,05) em todos os tratamentos. No terceiro experimento, foram comparados 4 tratamentos: Tris com 20% de gema de ovo e 110 mM de trealose (T1); Tris com 8% de LDL, incluindo 5% de glicerol (T2); Tris com 8% de LDL, incluindo 110 mM de trealose (T3); Tris com 8% de LDL, incluindo 110 mM de trealose e 5% de glicerol (T4). A motilidade dos espermatoz??ides para o T2 e para o T3 foram superiores aos demais tratamentos (P < 0,05), mas, com rela????o ?? integridade de membrana, n??o houve diferen??a entre os tratamentos com LDL (P > 0,05). A integridade do acrossoma n??o diferiu entre os tratamentos (P > 0,05). Portanto, o uso de LDL e trealose como crioprotetores foi associado com melhorias na motilidade e na integridade da membrana esperm??tica, no s??men ovino, ap??s o descongelamento.The low pregnancy rates obtained with artificial insemination using frozen ram semen make its routine use unfeasible. As the cryopreservation process causes injuries in the sperm cells, the development of extenders that include state-of-the art cryoprotectant solutions is justified. This study tested the inclusion of low density lipoprotein (LDL) and trehalose in extenders for freezing ram semen, by evaluating parameters of post-thawing semen quality. In the first experiment, 3 treatments were compared: Tris including 20% egg yolk and 5% glycerol (T1); Tris including 10 mM trehalose (T2); and T1 including 50 mM trehalose (T3). Sperm motility did not differ across treatments (P > 0.05), but T2 presented higher proportion of sperm cells having membrane integrity (P < 0.05). In the second experiment, 4 treatments were compared: Tris including 20% egg yolk (T1); T1 including 5% glycerol (T2); T1 including 100 mM trehalose (T3); and t1 including 100 mM trehalose and 5% glycerol (T4). Sperm motility and membrane integrity were higher for T2, T3 and T4 than for T1 (P < 0.05), but acrossome integrity did not differ among treatments (P > 0.05). In the third experiment, four treatments were compared: Tris including 20% egg yolk and 100 mM trehalose; and T1 with the replacement of egg yolk by LDL including 5% glycerol (T2); 100 mM trehalose (T3); and 100 mM trehalose and 5% glycerol (T4). Sperm motility and membrane integrity were higher for T2 and T3 than for the other treatments (P < 0.05), but there was no further difference among the LDL treatments (P > 0.05). Acrossome integrity did not differ across treatments (P > 0.05). Therefore, the inclusion of LDL and trehalose as cryoprotectants in extenders for frozen ram semen was associated with improvement in post-thawing sperm motility and membrane integrity