A influência da idade na resistência à refrigeração do sêmen de garanhões

Abstract

This work evaluates the resistance to cooling of the semen of stallions of different ages for this, 5 animals were separated into two groups: young animals (2 stallions up to 8 years old) and elderly animals (3 stallions from 12 years old). Two seminal collections were performed per animal. Soon after collection, the semen was diluted in skimmed milk-based extender (Botusemen®) at a concentration of 25 to 50 million spermatozoa/mL. Evaluations of total motility (%) and vigor (1-5), in optical light microscopy, and plasma membrane integrity (% damaged plasma membrane – MPL), using the eosin-nigrosin technique, were performed in two moments: immediately after harvesting (MOT 1, VIG 1, MPL 1) and after 6 hours of refrigeration in a passive transport isothermal box (Botuflex®) at 15°C (MOT 2, VIG 2, MPL 2). In addition, analyzes of concentration (in a Neubauer chamber) and sperm morphology (phase contrast microscopy) were also performed in all ejaculates. The collected data were compared using the Statistical Analyzes Systems program (SAS version 9.4; SAS Institute, Inc., Cary, NC, USA) and previously checked for normality of the residues using the Shapiro-Wilk test. Normal or transformed data were submitted to the analysis of variance test (ANOVA), followed by the observation of differences between groups, when significant, by the T test (PROC TTEST). The results were presented as mean and standard deviation. For all comparisons, a statistical significance level of 5% (p≤0.05) and a statistical trend level of 10% (0.05 < p < 0.1) were used. MOT1 showed values of 52.5 (±32.78) in young animals and 31(±20.12) in elderly animals. The MOT 2 was 41.25 (±33.75) in young animals and 18.00 (±13.50) in old animals. The VIG 1 was 2.75 (±1.5) for young stallions and 2.20 (± 0.84) for old stallions. The VIG2 was 2.5 (±1.29) for the young and 1.4 (±0.54) for the elderly. MPL1 showed 44.62 (±11.27) in young stallions and 36.6 (±16.44) in old stallions. After refrigeration, MPL2 values were 47.25 (±10.52) and 36 (±14.5) in young and elderly, respectively. There was no statistical difference in the results of sufficient sperm concentration and morphology between the groups, with exception for motility and membrane integrity that had differences between the groups and without relevance in the standard deviation, due to the number of animals it is suggested that if the experiment is done on a larger scale, possibly, a difference in resistance to cooling at different ages is evidenced, opening the possibility of future studies.