Viabilidade do sêmen de ovinos Morada Nova branca conservado em tris-gema nas épocas seca e chuvosa

Abstract

The aim of this study was to determine if there is a difference in semen viability and biochemical characteristics of blood and seminal plasma, between dry and rainy seasons. The experiment was carried out at the Animal Reproduction Studies Laboratory of the Department of Animal Science - UFC. Five sheep of the breed Morada Nova variety Branca were used, housed in individual bays, managed under intensive conditions and fed according to the animal category and species. The seminal diluents used were TRIS and TRIS-egg yolk. Samples of semen and blood were collected weekly during rainy and dry seasons. Two ejaculates of the same animal were obtained, with the purpose of acquiring a larger volume of semen. The seminal samples obtained were evaluated for volume (ml) and sperm concentration (x109sptz / ml) and then divided into two aliquots: (i) The first aliquot, immediately centrifuged to obtain seminal plasma and analyzed for concentrations of (ii) The second aliquot, diluted in the TRIS and TRIS-yolk diluent at a final concentration of 400x106 sptz / mL. After dilution, a 300 μl sample of semen was submitted to the thermoresistance test (TTR) for subjective evaluation of motility and vigor. The remainder of the diluted semen was cooled for 24 h and again submitted to TTR, for subjective evaluation of motility and vigor. Semen smears from the fresh and preserved samples were performed at the end of the TTR for knowledge of possible morphological changes. The smears were stained with blue bromophenol solution and 200 cells analyzed on each slide. Blood samples were analyzed for total protein, albumin, globulin, beta hydroxybutyrate and glucose concentrations. The data obtained were analyzed by the statistical program SAS 9.1. The results of this experiment suggest that there was no significant difference for the majority of semen viability parameters between the dry and rainy periods, with better volume values in the dry period, due in part to the greater adaptability of these sheep of the variety Morada New to aridity conditions in northeastern Brazil. Regarding blood characteristics, the glucose and globulin parameters were obtained, showing better results in the dry period.