Repeated matings with individual ewes by rams differing in sexual performance

Area of Science:

• Animal Science
• Reproductive Biology
• Behavioral Ecology

Background:

• Understanding ram sexual performance is crucial for efficient sheep breeding programs.
• Serving capacity, defined by ejaculation rate, influences mating behavior and reproductive success.

Purpose of the Study:

• To investigate the relationship between ram sexual performance levels and mating patterns with individual ewes.
• To determine if high-performing (HP) rams, characterized by rapid ejaculation, differ in mating incidence with individual ewes compared to low-performing (LP) rams.

Main Methods:

• Twenty-four sexually mature rams were individually exposed to 10 estrous ewes over three separate occasions.
• Sexual performance was assessed by ejaculation rate (serving capacity).
• Mating incidence, including repeated matings with individual ewes and the number of different ewes mated, was recorded.

Main Results:

• HP rams achieved six ejaculations in a shorter time and mated fewer times with individual ewes compared to LP rams (P < .01).
• Consequently, HP rams tended to mate with a greater number of different ewes than LP rams (P < .06).
• The time to achieve six ejaculations was inversely correlated with the number of unique ewes mated (P < .03).

Conclusions:

• Rams with higher ejaculation rates (HP rams) are more effective in covering a larger number of ewes.
• Utilizing rams with rapid ejaculation rates is advantageous for breeding large groups of ewes, whether naturally cycling or synchronized.
• This study supports the selection of rams with superior serving capacity for enhanced breeding efficiency in sheep production systems.