This article considers causes of variability in male sexual performance and identifies management techniques that can be used to improve the reproductive success and efficacy of our captive animal populations.

Male sexual behavior.

Effect of undegradable protein supply on testicular size, spermiogram parameters and sexual behavior of mature Assaf rams.

Clinical evaluation of reproductive ability of rams

The purpose of this study was to compare the sexual performance of rams that differed in age (maturation) and sexual experience. Twenty-four ram lambs (8 mo of age) and 21 rams (20 mo of age) were individually exposed to four females in hormonally induced estrus for 30 min on five occasions, 7 d apart. Half (12) the ram lambs and nine of the yearlings were sexually naive at the start of testing (had been denied access to females since weaning); the remaining males were sexually experienced. The sexual performance of the virgin rams was poorer during the initial exposure to females than in subsequent tests, whereas the sexual behavior of the sexually experienced males did not change over the days of testing. Sexually naive ram lambs and rams exhibited an improvement in sexual performance between Tests 1 and 2; during Test 3 to 5 the sexual performance (ejaculations per test) of sexually naive and experienced rams was similar. The only effects of age (maturation) on sexual performance during the last three test days were a higher frequency of mounts without ejaculation plus mount attempts (P less than .03) and a greater number of mount interactions per ejaculation (P less than .02) by ram lambs. In conclusion, one or two relatively brief exposures to estrous females can bring the sexual performance of virgin rams up to levels comparable to that of experienced males. Also, ram lambs in good condition exhibit acceptable levels of sexual performance.

Sexual performance of rams as determined by maturation and sexual experience.

Artificial selection of rams for sexual performance and its effect on the sexual behavior and fecundity of male and female progeny.

The serving activity of seven rams in one 20-minute pen mating test followed by two one-hour pen mating tests was recorded. The mating performance of each ram during a single-sire flock mating was subsequently monitored. Mean number of services in the two one-hour pen tests gave the best prediction of the number of ewes inseminated during flock mating (r = 0.88, P < 0.01). The number of services in the 20-minute test gave a poor prediction of the number of ewes inseminated (r = 0.30). The total number of services during the first 20-minutes of the two one-hour tests (2x20-minute tally), the number of services during the 20-minute test and the first 20 minutes of the first one-hour test (2 x 20-minute tally) and the number of services during the 20-minute test and the first 20 minutes of the two one-hour tests (3x20-minute tally) were only moderately correlated with number of ewes inseminated (r = 0.67, r = 0.47 and r = 0.64, respectively). These results explain why other workers, using combinations of 20-minute tests, have failed to demonstrate a relationship between pen mating tests and flock fertility. The results further show that a measure of the serving activity of rams in pens can be used to identify rams that are capable of mating large numbers of ewes, and that the development of a commercially applicable test is worthwhile.

RJ Kilgour

Papers

The relation between mating activity of rams in pens and subsequent flock mating performance.