EFEITO DOS MEIOS DILUÍDORES MMC (MÍNIMA CONTAMINAÇÃO) E LGM (LACTOSE-GEMA MODIFICADO) NA VIABILIDADE DO SÊMEN DE CÃES CONSERVADO POR 24 HORAS EM EQUITAINER®.

The aim of this study was to compare the viability of canine semen after dilution in Minimum Contamination Medium (MMC) and Modified Lactose-Egg yolk extender (LGM) and incubation at 4 oC for 12 and 24 hours. Thirteen ejaculates were collected from 5 adult dogs by digital manipulation. Macroscopic and microscopic characteristics were assessed right after collection. Semen was divided to be diluted (1:3) in MMC and LGM and subsequently chilled in Equitainer®. Seminal parameters of motility and spermatic morphology, membrane integrity (hyposmotic test), spermatic viability and spontaneous acrosome reaction (Trypan-blue Giemsa stain) were evaluated in fresh and chilled semen after 12 and 24 hours of incubation at 4 oC.  No difference between extenders was identified in semen conservation after 12 hours. After 24 hours just spermatic motility was different (p>0.05). But, after both periods of conservation, semen diluted in LGM maintained most of the characteristics verified in the fresh semen. The mean of true and false acrosome reaction did not exceed 2% in both semen extenders, which demonstrates no influence of media component and incubation period on these phenomena at 4 oC. In conclusion, these results indicate that both extenders can be used in canine semen conservation at 4 oC in conteiner during 12 hours without significant changes in semen characteristics. KEYWORDS: Dogs, sperm, cooling.