Effect of dilutors and times of equilibrium in the criopreservation of ovino semen (Ovis aries)

Lourdes Ramos Zarate; Abel Rojas Pardo; Zenón Martínez Flores

Abstract

The breeding and production of sheep in Bolivia is important in social and economic aspects, cryopreservation and artificial insemination are reproductive techniques for genetic progress. However, insemination with frozen semen is not satisfactory because of the low fertility rate, which can be prevented with the use of an adequate dilutor. The objective of the research is to evaluate and compare the effect of three seminal diluters in two equilibrium times on ovum sperm motility for cryopreservation. The work was developed in the cryopreservation laboratory of the Experimental Station of Choquenaíra, of the Major San Andrés University, the biological material was three male sheep in reproductive ages of 1.7, 2.7 and 4.5 years of the Corriedale breed. Used diluents were TGY, TRILADYL and CY at equilibrium times of four and eight hours. The effect of age on macroscopic characteristics, mass and sperm motility in the diluted and frozen semen, post-thaw sperm motility for diluents and for equilibrium times was evaluated. The mass motility was 55.55%, 38.89% and 5.55% for Scales 5, 4 and 3 of Herman Swanson. The ages did not influence the individual motility, but they influenced the percentage of dead sperm with 12.67%, 10.00% and 7.50% and percentage of abnormal sperm with 15.80%, 13.00% and 9.70% for the ages of 1.7, 4.5 and 2.7 years. The sperm concentration was 3.14x109 ml^-1, 3.12x109 ml^-1 and 2.86x109 ml^-1 and the sperm motility was 66.50%, 66.33% and 64.50% for 2.7, 4.5 and 1.7 years, the diluters showed a motility of 67.67 % TGY, 65.17% CY and 64.50% TRILADYL with influence of 68.22% in four hours and 63.33% in eight hours of equilibrium times. The age of the sheep to obtain better semen quality is 4.5 years and the TGY dilutor is the best option to obtain greater sperm motility and prevent sperm damage during its cryopreservation process, achieving higher fertility rates at the time of artificial insemination.