Comparative Evaluation of Embryo Quality and Developmental Competence in Nguni, Bonsmara, and Boran Cattle Breeds Under Smallholder Farming Conditions in South Africa

The objective of this study was to assess the developmental competence and quality of embryos produced by Bonsmara, Nguni, and Boran cattle in a smallholder production environment using in vivo and in vitro techniques. This was a 3 x 2 factorial experiment in a completely ran-domized design, with breed (3 breeds) and embryo production tech-nique (2 methods) as factors. In vivo embryos were produced by ad-ministering hormones to experimental cows, while in vitro embryos were developed through ovum pickup and ovarian follicle aspiration. Embryo developmental competence was evaluated based on cell divi-sion stages, while embryo quality was assessed morphologically fol-lowing the standards of the International Embryo Transfer Society. The effects of breed and embryo production technique on developmental competence and quality were analysed using a linear fixed-effects model with the General Linear Models procedure in SAS software. Results showed that in vivo blastocyst development on day 8 was sig-nificantly (P< 0.05) higher in Bonsmara and Nguni cattle compared to Boran. However, no significant breed effects were observed on embryo developmental competence at any stage when using the in vitro tech-nique. Bonsmara cattle produced a significantly higher number of poor-quality (Grade III) embryos compared to Nguni and Boran. Addi-tionally, both flushing and ovum pickup methods yielded a significantly (P< 0.05) higher number of blastocysts and excellent-quality (Grade I) embryos compared to ovarian follicle aspiration. Overall, the study demonstrated that the in vivo method of embryo production is superior to the in vitro method in promoting blastocyst development in Bonsmara, Boran, and Nguni breeds.