Role of Open Nucleus Breeding Systems in Livestock Genetic Improvement: A Review

The Open Nucleus Breeding System (ONBS) is a genetic improvement strategy that integrates elite breeding stock within a nucleus herd and facilitates two-way gene flow with base populations, thereby enhancing genetic gain while maintaining diversity. It differs from Closed Nucleus Breeding System (CNBS) by allowing the incorporation of outstanding animals from base herds into the nucleus, which broadens the genetic base, reduces the risk of inbreeding, and improves adaptability to local production environment. ONBS is suitable for both smallholder and large-scale operations. Integration with technologies like Multiple Ovulation and Embryo Transfer (MOET) further improves genetic progress by reducing generation interval and increasing the number of offsprings from valuable females. Community based breeding programs (CBBPs) when combined with ONBS enhance farmer participation, cost effectiveness, and sustainability. Collectively, ONBS and its adaptations provide a viable pathway for livestock improvement.