99 Effect of application of seminal plasma on Day 0, 5, or 7 postmating on pregnancy rate and embryonic survival in alpacas (Lama pacos)

Abstract

Alpacas, similar to other camelids, are classified as induced ovulators, as an external stimulus is required for the occurrence of ovulation. A protein identified as β-nerve growth factor, present in the seminal plasma (SP), has the capacity to induce ovulation and corpus luteum formation. Alpacas exhibit poor reproductive efficiency, with birth rates below 50% due in part to high embryo mortality before 35 days post-mating. A study was carried out to evaluate the effect of the application of SP on Day 0, 5, or 7 post-mating on pregnancy rate and embryo survival, defined as the difference in the numbers of pregnant females between Day 35 and 25. Nonpregnant adult alpaca females (n=124) between 5 to 6 years old were evaluated by transrectal ultrasonography to determine presence of a follicle ≥7mm, and then 2 days later to confirm permanence of the follicle. Alpacas were then bred by natural mating and assigned randomly to 1 of 4 treatments: 1mL of SP IM at mating; 1mL of SP IM Day 5 post-mating; 1mL of SP IM Day 7 post-mating; and control. Semen was collected from adults male and ejaculates were diluted 1:1 with PBS and then centrifuged for 30min at 3000 rpm. Supernatant was separated and a drop evaluated to determine absence of spermatozoa and SP-free sperm was stored at −20°C. Twenty adult males with optimal reproductive performance were used for mating with females assigned to the different treatments. Animals were evaluated by ultrasound with an Aloka SSD 500 (Aloka, Tokyo, Japan) and 5.0-MHz linear transducer on Day 25 and 35 to determine pregnancy rate and embryonic survival. Data were analysed by chi-square. Results are present in Table 1. The results differ from our initial hypothesis and a possible explanations may be that additional application of SP IM could saturate receptors and block the action of the seminal plasma present in the ejaculate of males. Table 1.Pregnancy rate and embryonic survival in alpacas with application of seminal plasma on Day 0, 5, or 7 Study was supported by project no. 405-PNICP-PIAP-UNMSM.