219 Serum levels of interleukin-10 and progesterone post-mating in alpacas (Vicugna pacos)

Interleukin-10 (IL-10) and progesterone (P₄) play crucial roles in gestational maintenance. Interleukin-10 has an immunological function, suppressing inflammatory responses, while P₄ exerts a positive effect on Th2 lymphocytes, responsible for expressing cytokines like IL-10. The aim of this study was to determine the serum levels of IL-10 and progesterone P₄ in alpacas post-mating. Female alpacas (n = 10) aged 6 to 8 years were evaluated using ultrasound to determine follicles ≥7 mm in size. Subsequently, they were mated with fertile males (n = 7) for all the female alpacas for a minimum mating time of ≥15 minutes. Blood samples were collected at Days 0, 12, 15, 18, 21, 24, 27, and 30 post-mating, with Day 0 corresponding to the mating day. Samples were centrifuged to obtain serum, which was stored at −70°C until analysis. Male receptivity testing was performed on Days 15 and 18 post-mating, while pregnancy determination was done via ultrasound on Days 21, 24, 27, and 30 post-mating. The female alpacas were divided into three groups: G1 (n = 4): pregnant alpacas at Day 30; G2 (n = 2): alpacas with rejection of the male at Day 18 and confirmed on Day 21 for ultrasound as alpacas with embryonic death, and G3 (n = 4): empty alpacas. The IL-10 levels were determined using a competitive bovine ELISA kit, and progesterone was measured using a RIA kit for the 8 days of evaluation. Data were analysed using the R statistical program, and median comparisons were conducted using Kruskal–Wallis for IL-10 and P₄ profiles. Additionally, Spearman correlation coefficient test was applied to evaluate the relationship between P₄ and IL-10 in the 3 groups of female alpacas on the different days evaluated. The results for IL-10 (pg mL⁻¹) were G1 (23 ± 7.02), G2 (20.29 ± 1.76) and G3 (6.76 ± 3.62) and in P₄ (ng mL⁻¹) were G1 (5 ± 0.43), G2 (3.34 ± 0.49) and G3 (0.76 ± 0.06), with significant differences in IL-10 levels between alpacas in G1 and G3 (P < 0.05) and between G2 and G3 (P < 0.05). Significant differences in progesterone (P₄) were observed between G1 and G3 (P < 0.05) and between G2 and G3 (P < 0.05), with a nonlinear correlation (r = 0.35) between IL-10 and progesterone. These findings suggest that IL-10 may be associated with the maintenance of pregnancy in alpacas.