Effect of repeated collection on semen characteristics of alpacas

Semen characteristics of alpacas were studied after repeated collections. Twelve adult males were divided into three groups of four each for semen collection once, twice, or three times every other day. The duration of copulation; volume of ejaculate; pH; motility; sperm concentration (number of sperm/milliliter semen); total number of sperm per ejaculate; and percentages of live, normal, and abnormal spermatozoa were analyzed by regression analysis. Semen color and consistency were analyzed by the chi-square test. Between the first, second, and third ejaculations, there were differences (p < 0.05) in sperm concentration; percentages of normal spermatozoa and abnormal spermatozoa; sperm with abnormal heads and abnormal tails; and consistency (viscous, viscous, and semi-viscous). There were no differences (p > 0.05) in ejaculated volume, percentage of live spermatozoa, pH, percentage of cytoplasmic droplets, and duration of copulation. Some males from which semen was collected on the three-mating schedule ejaculated only seminal plasma during the second and third copulation starting on Day 10 of the study. There were differences between males (p < 0.05) for most of the characteristics studied. In sum, frequency of mating affected some semen characteristics that may be important determinants of the fertility of male alpacas.