LEVEL OF TESTOSTERONE IN BLOOD PLASMA OF SELECTED RAMS

Following importation of temperate Australian breeds of sheep into Malaysia, it was demonstrated that there was variability in libido and semen productivity. Consequently, a study was conducted to determine the concentration of testosterone and relate it with libido and semen production. A total of 10 rams each of Dorset Horn, Cross of Merino with Border Leicester, Siamese Long Tail, Suffolk and local Malin were used to study the composition of testosterone in the blood plasma of these breeds. The study showed that there was significant difference between the testosterone level of different breeds in Spring and Summer but not in Autumn and Winter. The difference was pronounced in August and January. A significant difference (p > 0.05) was recorded in the testosterone levels of the different breeds during the day where Malin had better libido compared to the other breeds. There was no significant difference between the testosterone levels of the different breeds at night. The testosterone level of Suffolk, however, was elevated throughout the night (2.00 ng/ml and over) which resulted in better libido at night compared to the other breeds.