Tim Barnes, OSU Extension Educator, Marion County
To achieve maximal fertility, rams should be physically examined for reproductive fitness to detect abnormalities that may affect breeding performance. A breeding soundness examination can be completed before breeding season. The scrotum and its contents as well as the penis and prepuce must be carefully examined. The size and symmetry of both testes and epididymides should be assessed, and both testes should be firmly palpated for consistency and resilience. Semen can be collected and evaluated to check potential sires, particularly in ram lambs. All screening procedures should be done 2-3 weeks before mating to allow management changes if a ram needs to be replaced in the breeding program.
Supplementary feeding of the ram can be started 6 weeks prior to breeding season. High protein rations can increase both testicular size and number of cells in the germinal layers of the testicle, resulting in increased sperm production.
Mating activity may be monitored by using a breeding harness on the ram and changing the color of the crayon color every 14-17 days. When fewer than expected ewes are marked, poor ram libido, insufficient number of rams to breed the flock, or anestrus is suspected. When ewes are serially marked with different colors, conception failure or early embryonic death is possible.
The ram to ewe ratio varies with breed and whether synchronization or induction of estrus has been practiced. For ram effect, the ration should be 1:20; for estrus synchronization, 1:10 to 1:15 (in season); and estrus induction (out of season), 1:15 to 1:17.
Length of ram exposure during the breeding season should be limited to two or three cycles so the lambing period will be shorter and this will optimize lambing management. Excellent fertility can be achieved with a breeding exposure of 35-42 days. Poor fertility indicates an issue with the ram management. Flock movement should be avoided at mating, but normal handling should not affect mating. Because younger ewes have a shorter, less intense estrous period, they are better mated separately from older ewes with experience rams.