Semen quality and bacteriological profile of semen collected by three methods and fertility in Huacaya alpacas (Vicugna pacos) inseminated with fresh postcopulatory semen.

Alpacas (Vicugna pacos) are South American camelids adapted to the high-altitude Andean ecosystem of Peru, above 4,000 m. In this study, semen quality, bacteriological profiles of the prepuce, vagina, and semen collected by postcopulation (PC), artificial vagina (AV), and electroejaculation (EE) methods, and fertility were evaluated in Huacaya alpacas inseminated with fresh PC semen at different times after ovulation induction. A total of 150 Huacaya alpacas (45 males and 105 females) between 4 and 8 years of age were used. Macroscopic and microscopic semen quality parameters, semen bacteriological profiles, and quantitative determination of bacterial load (colony-forming units [CFU]/μL) were evaluated. For these 3 study variables, 30 males were used; these animals were distributed in 3 methods (10 for each method): PC, AV, and EE. In addition, 10 females were included in the postcopulatory method. A total of 10 males and 10 females were used for the bacteriological profile (prepuce and vaginal, respectively). For the fertility test, 80 females (20 for each insemination time) and 5 males (semen donors) were used. Moreover, five females were used for postcopulatory semen collection. Donor semen obtained by the PC method showed significantly higher values for motility (69.1 ± 2.3%), viability (82.8 ± 1.3%), HOST positivity (77.9 ± 1.3%), acrosomal integrity (85.2 ± 1.3%), and seminal volume (2.9 ± 1.8 mL) than those obtained by the AV and EE methods. In contrast, higher viscosity was recorded for AV semen, followed by EE and PC. Regardless of the collection method, the bacteria isolated from the prepuce, vagina, and semen were Streptococcus sp., Staphylococcus sp., Escherichia coli, Nocardia sp., Bacillus sp., and Micrococcus sp. Fertility rates of 45, 50, 35, and 30% were obtained in alpacas inseminated at 24, 26, 28, and 30 h postinduction, respectively, with significant differences between 26 h and the later time points. These results demonstrate significant differences in semen quality parameters and bacterial profiles among collection methods and indicate that 26 h postovulatory induction is the optimal time for artificial insemination with fresh PC semen.