Factors affecting in vitro maturation of alpaca (Lama paco) oocytes

Abstract

The present study utilized a 2×2×2 factorial design examining age (old vs. young), follicle size (≥2mm vs. <2mm) and media supplementation (with or without fetal bovine serum [FBS]) to determine factors that might affect in vitro maturation of alpaca oocytes. We hypothesized that oocytes collected from follicles ≥2mm from young alpacas and incubated in maturation media supplemented with FBS would have greater maturation rates than those incubated in any other factorial combination. Oocytes were collected from the ovaries of 11 young alpacas (<10 years old) and 14 old alpacas (>11 years old). Oocytes were classified as morphologically normal oocytes (MNO) and deemed suitable for incubation if ≥3 compact layers of cumulus cells and a homogeneous, evenly granulated cytoplasm were observed. Oocytes from each group of follicle sizes were incubated separately and halves of each group were randomly divided and incubated 24h in chemically defined maturation media with or without 10% FBS. Maturation was defined as the visualization of a polar body at the end of the incubation period. Overall, a greater proportion of MNO were collected from follicles ≥2mm than that obtained from smaller follicles, 55% (136/247) vs. 29.6% (162/547), respectively (P<0.05). A greater proportion of oocytes reached maturation when collected from ≥2mm follicles 36% (49/136) than from <2mm follicles 8% (13/162) (P<0.05). For oocytes obtained from ≥2mm follicles of old alpacas, a greater proportion reached maturation when incubated in media supplemented with FBS than when incubated without FBS; 57.6% (19/33) vs. 18.2% (6/33), respectively (P<0.05).

Effect of FSH and eCG on Alpaca (Vicugna pacos) Oocyte Maturation in vitro

“…In this study, lower oocyte maturation rates (45.3 and 47.3%) were found when using concentrations of 0.25µg.mL -1 of FSH plus 5 or 0IU.mL -1 of eCG. These results suggest that when using low concentrations of gonadotropins, the rates of oocyte maturation decrease, as reported by Leisinger et al (2014), in which 15ng.µL -1 of FSH resulted in a 37.9% maturation rate of alpaca oocytes. In groups without FSH supplemented with any concentration of eCG, maturation percentages were low (8.0 to 11.4%).…”

“…Other investigations used 5% oxygen and 5% CO2 at 38 to 39°C. However, this study utilized 6% oxygen and 6.1% CO2 at 38.5°C, similar to the reports by Leisinger et al (2014), in which 6% CO2 at 38°C was used in the incubation of alpaca oocytes. The in vitro environment used in the maturation of alpaca oocytes is still inadequate, therefore studies are needed to improve in vitro maturation protocols (Ruiz et al 2017).…”

“…Differences between different culture media can be attributed to the composition of media, as well as differences in their ionic concentration (Farag et al 2013). This assumes the composition of media used for the maturation of oocytes in vitro plays an integral role in oocyte development competence (Leisinger et al 2014). Currently, different combinations of gonadotropins are utilized to try and improve in vitro maturation of oocytes; however, it is difficult to determine the dose to be used, especially in cases of combined protocols (Wang et al 2013).…”

“…In vitro embryo production can improve genetic progress (Mutembei et al 2016). However, it is not yet efficient in camelids, as this technology in alpacas progresses slowly when compared to other traditional livestock species (Tibary et al 2005) and development is in the initial stages (Leisinger et al 2014). There are several factors that limit optimal in vitro embryo production (Tibary et al 2005), especially in vitro culture conditions which have not yet been addressed in camelids (Ratto et al 2005).…”

Comparison of Two In vitro Maturation Media in Their Efficiency for Production of Competent Alpaca Oocytes

“…During this process, the oocyte must complete its final growth, and nuclear and cytoplasmic maturation [13]. In vitro maturation in alpacas is commonly carried out by extrapolating culture medium from cattle to alpacas, generating highly varied results [14].…”