Number Of Completed Matings Research Articles

Sexual stimulation in male sheep and goats

Previous research has shown that the sexual performance of male goats is enhanced by viewing the mating activities of other males prior to being placed with sexually receptive females. This same experience has no effect on the sexual performance of male sheep. In the present experiment, 14 male goats and 17 rams were individually allowed to sniff and nuzzle the anogenital region of an estrous female and engage in premating behaviors, but not mount for 20 min immediately prior to the administration of 30-min sexual performance tests. A female-absent control treatment was administered to these same animals prior to sexual performance tests. In the sexual stimulation treatments, male goats were more sexually active than rams ( P<0.001 for all variables). However, sexual stimulation did not affect the subsequent sexual performance of either species ( P>0.20 for all variables). Male goats and sheep did not differ ( P>0.05) in number of completed matings (services) but male goats exhibited more mounts without ejaculation ( P<0.001) and more mounts per service ( P<0.001) than rams. These results are discussed in terms of the reproductive advantage of sexual stimulation to male ungulates in the context of male–male competition vs. the absence of male competitors.

Sexual Behavior of Rams as Influenced by the Degree of Restraining Estrous Ewes and by the Additional Presence of Anestrous Ewes

The purpose of this study was to determine whether the sexual performance of rams in serving capacity tests was influenced by the degree of restraining estrous ewes (in stanchions, tethered or unrestrained) and the additional presence of nonreceptive (anestrous) ewes. Twelve rams, previously identified as low-level sexual performers, were exposed individually for 15-min periods to four estrous ewes presented in each of six conditions: in stanchions, tethered and unrestrained, with and without four unrestrained anestrous ewes present. The degree of restraining estrous ewes influenced ram behavior. Rams investigated unrestrained and tethered estrous ewes more times than ewes in stanchions (P < .01 and P < .05, respectively). The frequency and duration of ram courtship behaviors also were greater when the ewes were unrestrained or tethered than when they were in stanchions (all P < .01). Rams tended to mount unrestrained ewes more times than ewes in stanchions (P < .10); however, serving capacity (number of completed matings per unit of time) was not influenced by the degree of restraining estrous ewes. The presence of anestrous ewes reduced the frequency and time spent investigating and the number of ejaculations with estrous ewes (all P < .01) and increased the latency to first ejaculation (P < .01). When estrous ewes were given more freedom to move about, rams investigated and courted estrous ewes more and anestrous ewes less (all interactions were significant). In conducting sexual performance tests with rams, only ewes observed to be in standing estrus should be present in the testing pen.

The Influence of Daylength, Body Weight, and Age on the Reproductive Ability of Broiler Breeder Cockerels

June-hatched broiler breeder cockerels of two strains were evaluated for reproductive performance in mating pens from 22 to 48 weeks of age. Two light programs with maximum daily daylengths of 15.5 or 16.5 hr were studied.An increase in the light day to 16.5 hr did not significantly affect the male reproductive traits except in number of completed matings and percent packed sperm volume (PSV). The males on 16.5 hr of light had significantly fewer completed matings than did the males on 15.5 hr. Strain 1 males on 16.5 hr produced significantly more spermatozoa at 35 and 40 weeks of age than males on 15.5 hr of light. Male body weights of both strains were significantly lower at 30 weeks of age on the longer daylength. Body weights of cockerels in all treatment groups increased with aging. The range in male body weight markedly influenced the percentage of producing cockerels with aging. During the late egg cycle, the number of producing males increased as body weight increased.The overall mean age of peak in the percentage of males in semen production was 44 weeks of age, which was 7 weeks later than peak egg production. Hatchability was significantly lower for male Strain 2, which had a higher percent PSV and a higher number of attempted matings than did Strain 1.Body weight was significantly correlated with male vent feather-wear at all ages and with the percentage of producing males at 48 weeks of age. The percentage of producing males was correlated with vent feather-wear, evert score, semen volume, and PSV.These results emphasize the importance of body weight selection for optimum breeding flock performance.

Mating frequency in male chickens: long-term selection

Twenty-three generations of bidirectional selection in male chickens (Gallus domesticus) for number of completed matings resulted in widely diverse mating behavior in the high and low lines. Selection caused a steady increase in cumulative number of completed matings (CNCMs) of the high line with a realized heritability of 0.18±0.02. In contrast, selection for decreased CNCMs caused many males to pass a threshold below which they would not mate naturally. Changes in male mating behavior were not accompanied by changes in mating behavior of females.

Response to bidirectional and reverse selection for mating behavior in Japanese quailCoturnix coturnix japonica

Reported is a genetic analysis of mating behavior in male Japanese quail. Data were obtained from replicated experiments involving 12 generations of divergent selection for high and low cumulative number of completed matings (CNCM). No trait measured in the randombred control population changed significantly over time. Asymmetrical responses between the divergent lines were observed during various phases of selection. Reversed selection showed that additive genetic variance remains in the high lines. Small and unimportant were drift and error variances. Genetic and phenotypic relationships between CNCM and body weight were small but positive, while those between CNCM and relative aggressiveness were positive and intermediate. Also positive and intermediate were the correlations between CNCM and cloacal gland size.

INTERRELATIONSHIP OF COMB LOCI AND MATING BEHAVIOR IN CHICKENS

Qualitative and quantitative data obtained from lines of chickens divergently selected for male mating ability and from the unselected randombred control population were used to evaluate the relationship of comb type alleles and mating behavior. An apparent antagonistic relationship was found between the rose (R) allele and low cumulative number of completed matings in the low mating line, while the opposite association was found for the pea (P) allele. No association was found between alleles of the rose and pea loci and mating ability in the high mating or control lines. An antagonistic relationship was indicated between the rough (He+) allele and a high cumulative number of matings. These results support the hypothesis that two genetical systems interact to influence the mating frequency of male chickens and further suggest that alleles of the rose, rough, and pea loci should not be used as marker genes to estimate genetic drift in random mating populations maintained by natural matings.