Reproductive Characteristics and Introduction of Artificial Insemination in Desert Sheep

Abstract

Two hundred Hamari rams and 80 Watish were examined to determine the most typical features of the reproductive tract; five age groups were included from < 1 year of age to 4 years. In addition to parameters normally used in selecting rams for breeding such as condition score and scrotal circumference, scrotal skin thickness was estimated and also the extent of any split in the scrotum between the testes. The presence of thongs used for contraception known as Kunan, evidence of its previous application, or its absence was noted. From these records normal standards were deduced and recommendations were made which would assist at the time of selecting stud males of those two breeds. Differences among seasons for characteristics in Hamari rams were not marked in this survey. Ewes and rams representing good quality of Hamari and Watish breeds were then purchased. In the 4 rams, semen was first evaluated using electroejaculation. Two rams, one of each breed, were subsequently trained to ejaculate into an artificial vagina (A.V), with the two methods of collection were compared. Semen quality was made using the A.V and in addition ejaculates obtained by good for the most part but concentration of spermatozoa per ml was consistently better when an A.V was used. On the female side, average length of the oestrous cycle was calculated and also duration of oestrus. Oestrous cycle length was longer than published references by 1 day at 17.6 days. When twice daily observations of onset oestrus were made the difference between morning and afternoon onsets was small. Artificial insemination was applied to two groups of ewes in which oestrus had been hormonally synchronized with intra-vaginal sponges. One group (10 ewes) each received 0.25 ml fresh concentrated semen and the other group (7 ewes) received the same volume of semen but diluted with 0.25 ml saline solution. A third group (12 ewes) was hand mated as controls. Results of the inseminations were judged on a non-return to oestrus basis. Ewes were daily tested with the teaser ram from about 25 days after mating until completion of the first third of normal gestation in the hand mated group, and until at least half way through gestation in the inseminated groups. A.I. with concentrated semen gave a 90% conception rate; with diluted semen 57.1% and hand mated controls were 91.6%. A.I. was successfully accomplished in this pilot study but further work is required before it can be extensively used, for the improvement of Sudanese Desert sheep.