Effect of nutritional status on the ovarian follicular population, yield and quality of oocytes in the Ngaoundere gudali zebu (Bos indicus)

Abstract

Aim: The aim of this study was to investigate the effect of nutritional status of the Gudali cows slaughtered at the Ngaoundere abattoir on follicular population, quality, and oocytes yield. Materials and Methods: Blood and ovaries were collected from 81 cows aged 6.35±0.24 years (3-12 years old), with a body condition score (BCS) of 2.93±0.09 (1-5). In each ovary, the follicle were counted and classified as small (<3mm), medium (3-8mm) and large (>8mm) using an electronic caliper. Oocytes were collected by slicing technique and classified according to the homogeneity of the cytoplasm and layers of granulosa into four groups: I, II, III, and IV. The nutritional status of the animals was determined by quantification of serum glucose, total cholesterol, total protein, albumin, globulins, urea, and phosphorus level. Results: Of the total 162 ovaries harvested, 2916 follicles were counted on the ovarian surface with an average population of 36.00±2.17follicles/cow. According to a size distribution, 16.67±1.54 (46.3%), 18.83±1.27 (52.3%), and 0.51±0.07 (1.4%), respectively for small (<3mm), medium (3-8mm), and large (>8mm) were recorded. About 1,929 oocytes were obtained, with an average recovered of 23.81±1.53oocytes/cow. Depending on the quality, 7.79±0.55 (32.7%), 6.04±0.41 (25.3%), 4.89±0.44 (20.6%), and 5.10±0.54 (21.4%) oocytes qualities I, II, III, and IV were obtained respectively; with an average cultivable oocyte recovered of 13.83±0.89 (58%). Cows with BCS > 3 and a high albumin and phosphorus level showed a highest number of follicles and oocytes able for in vitro maturation. Conclusion: These results indicated that nutrition remains an important factor for the in vitro production of the good embryo and the BCS is a useful tool for the selection of females' oocytes donors.