165 THE EFFECT OF INDIGENOUS CHICKEN EGG YOLK SOURCES AND TEMPERATURES ON SHORT-TERM PRESERVATION OF SOUTH AFRICAN INDIGENOUS GOAT SEMEN

Abstract

Egg yolk is a common constituent of semen extender and protects sperm against cold shock. Besides its protective characteristic, chicken egg yolk is mostly included in extenders for semen preservation due to its abundant availability. The aim of the study was to compare egg yolk sources from different indigenous chicken egg yolk sources and storage temperatures on short-term preservation of South African indigenous goat semen. Semen was collected from 8 South African indigenous goats with artificial vagina during the breeding season (autumn). From each of the 8 goats, 6 replicates were done. Semen samples were randomly allocated into 4 treatment groups of Tris-based extenders containing 20% of egg yolk from White Leghorn as a control, Ovambo, Potchefstroom Koekoek, and Venda chicken breeds. The extended semen samples were stored at 5 or 25°C for 48 h. Semen samples were evaluated for sperm motility using computer-aided sperm analysis sperm viability and morphology with fluorescence microscope at 0, 3, 24, and 48 h. Data was analysed with ANOVA using Stata® version 12 (StataCorp, College Station, TX, USA) statistical software to test the differences between the treatments. The total, progressive, and rapid sperm motility rates were higher in freshly collected semen (90.6, 42.7, and 33.0%, respectively) compared with treatment groups. Semen extended with Tris without egg yolk had higher total sperm motility rate at both 5°C (48.1; 51.1%) and 25°C (43.3; 53.3%) temperatures for 48 h. Semen extended with egg yolk from different egg yolk sources had no sperm motility from 24 h when stored at 25°C. Semen extended with Tris without egg yolk (48.1%) had higher sperm motility than Ovambo, Potchefstroom Koekoek, Venda, and White Leghorn (3.7, 0, 0, and 0.4%, respectively) when stored at 5°C for 48 h. However, sperm motility declined when storage increased. In conclusion, addition of egg yolk had no effect on preserving goat semen. However, Tris-based extender without addition of egg yolk preserved semen for longer period than semen extended with egg yolk regardless of egg yolk origin or chicken breed.