Influence of reproductive season and testicular volume on seminal parameters of alpacas (Vicugna pacos)

Abstract

The male alpaca plays an important role in the reproductive process and, consequently, in genetic improvement. South American camelids (SACs) have a well-defined reproductive season, particularly in the Andean region. The objective was to evaluate the influence of reproductive and non-reproductive seasons, as well as testicular volume, on seminal parameters in alpacas. Nine healthy male alpacas, over 4 years old, were selected for this experiment. Semen samples were taken every two days using an artificial vagina incorporated into a dummy. The collected were in the reproductive (November to April) and non-reproductive (May to October) seasons, from breeders with testicular volumes that range between 63–70 cm3 and 83–94 cm3. The total number of ejaculates collected was 72 per season, with 8 samples collected from each male. Macroscopic aspects such as color, volume (ml), thread formation (cm) and foam (cm) were evaluated, in addition to microscopic aspects such as sperm motility (%), viability (%) concentration (sperm/ml) and total number of sperm. The results were analyzed with the Mann–Whitney non-parametric test, using the R 3.4.3 software, considering P < 0.05 as the significance level. A decrease in thread formation was observed in semen collected during the reproductive season compared to the non-reproductive season (P < 0.05). On the other hand, sperm motility and viability in semen collected during the reproductive period was higher (p < 0.05). Regarding testicular volume, alpacas with larger testicular volume had greater ejaculate volume, sperm concentration and total number of sperm (p < 0.05). Based on these results, it is possible to conclude that the semen of alpaca breeders is influenced by the season, and that testicular volume can predict their reproductive capacity, being a parameter to be considered when selecting the best breeding male.