Parâmetros reprodutivos e criopreservação espermática de cervos sambar (Rusa unicolor)

Abstract

The information obtained on the reproductive biology of the sambar deer allows us to advance in conservationist research and contribute to studies on other endangered species of deer. In this context, the objective of this study was to evaluate the body, testicular, and tail biometrics of the epididymis and their correlations with the sperm characteristics of Sambar deer (Rusa unicolor), collected from the epididymis, evaluating the effects of cooling of the testicle epididymis complex at 5 ºC for 24 hours and the efficiency of different diluents in post-thawing sperm viability. Five adult sambar males of the Getúlio Vargas Zoobotanical Park, Salvador Ba. After anesthesia, the animals were ovariectomized and body, testicular, and tail measurements were estimated. The collected testicle-epididymal complexes were subjected to slice and flotation techniques to collect sperm from the epididymis tail in two moments. At first, the left complex was evaluated in nature, while the right one was subjected to a temperature of 5°C for 24 hours. The sperm samples collected from both treatments were diluted and cryopreserved in commercial OptiXcell (OP) medium and medium containing egg Tris-gema plus two cryoprotectors: glycerol (GL) and dimethylacetamide (DMA), in different concentrations, forming five experimental groups: G1 (GLI 3%); G2 (GLI 6%); G3 (OP); G4 (DMA3%) and G5 (DMA6%). The kinetics of sperm in nature, chilled, and after thawing were evaluated subjectively and through the computer-assisted semen analysis - CASA; functional integrity of the plasma membrane, by the hyposmotic test; integrity of the plasma and acrosomal membranes, using epifluorescence probes and mitochondrial activity. The data were evaluated for normality by the Shapiro-Wilk test, for variables that presented normal distribution, the data were submitted to Analysis of Variance, and for the variables that did not present normal distribution, the data were evaluated by the Kruskal Wallis test, adopting a significance level of 5%. The results showed that animals with greater head circumference (CFC), thoracic diameter (DT), withering height (AC), and body weight (PC) also have greater testicular and tail measurements of the epididymis. A positive and significant correlation (P<0.05) also existed between sperm parameters and testicle-epididymal biometrics. These data indicate that biometrics can be used as predictors of the reproductive efficiency of the sambar male and that the epididymal harvest can be an important source of sperm cells for reproduction programs in the species. When evaluating the effect of cooling for 24 h at 5ºC, a difference in the percentage of minor defects (P<0.05) was observed. In the post-thawing parameters, there was a difference in total motility, progressive, vigor, and sperm kinetics evaluated by CASA after thawing for the different experimental groups in both treatments (P<0.05). Inferring that the cooling of the testicle-epididymal complex preserved sperm kinetics and membrane integrity and can be used for assisted reproduction techniques and that diluents based on egg yolk and glycerol are more effective in preserving the viability of sperm, being preferable for sperm cryopreservation protocols of the sambar deer.