DIFFERENCES IN SEXUAL ACTIVITY BETWEEN RONDERIB AFRIKANER AND MERINO RAMS
P R King, W A Coetzer*, P A Schlebusch, E Roux, A P Pretorius & B R King
Grootfontein College of Agriculture, Middelburg Cape, 5900
*Department of Human and Animal Physiology, University of Stellenbosch,
Results on the effect of Ronderib Afrikaner rams on reproduction in Merino ewes over a 7 year period indicate that the lambing percentage of Merino ewes mated to Ronderib Afrikaner rams is higher than that of Merino ewes mated to Merino rams. This elevated lambing percentage is brought about by a higher ovulation rate (19% on average) in the Ronderib Afrikaner mated Merino ewes. In an attempt to find an explanation for this phenomenon, a study was done on the sexual activity of the Ronderib Afrikaner and Merino ram. Two groups of 15 Merino ewes each were synchronized with progesterone sponges. When all ewes displayed oestrus a Ronderib Afrikaner ram was placed with one group while a Merino ram was placed with the other for a 1 hour period. Ten Ronderib Afrikaner and 10 Merino rams were used in the study and each ram was observed 3 or 4 times. The number of times each ram mated successfully as well as the unsuccessful mating attempts were recorded. The Merino rams mated 1.26 ± 1.36 times on average per hour while the Ronderib Afrikaner rams mated 1.80 ± 1.79 times per hour (P>0.05). The unsuccessful mating attempts per hour for the Merino rams were 6.8 ± 5.35 compared to the 15.09 ± 11.62 for the Ronderib Afrikaner rams (P<0.01). From these results it would seem that the Ronderib Afrikaner rams are more active among the ewes than the Merino rams.
Proceedings 31st SASAP congress