Breeding systems for genetic improvement of dairy goats in smallholder production systems in Kenya

- We model a two-tier nucleus open and closed system.
- Breeding systems differed in the level of use of old or juvenile bucks.
- Use of old bucks realized faster response to selection compared to juvenile bucks.
- Juvenile system could be an alternative when profit maximization is the main focus.
- Response to selection for number of kids weaned and does survival rates were very low.

A deterministic simulation model was used to test the hypothesis that utilization of untested juvenile bucks could be an alternative to old buck strategy in dissemination of superior genetic materials in dairy goats breeding program. We compared the genetic and economic gains realised when the untested juvenile and old bucks were used to disseminate genetic materials in a two-tier closed and open nucleus breeding systems. In the untested juvenile buck strategy, 95 and 70% of nucleus and commercial does, respectively, were mated to the untested juvenile bucks. In the old buck strategy, all the females in the nucleus and 70% of commercial does were mated by old bucks from the nucleus. In the open nucleus system, 20% of the does born in the commercial sector were recruited into the nucleus to produce nucleus does of does. Utilization of untested juvenile bucks realised 5.92 and 7.30% more annual returns and profitability per doe, respectively compared to old buck strategy. The old buck strategy, however, outperformed untested juvenile buck strategy by 23.37 and 14.85% in total annual genetic gain in closed and open nucleus breeding systems, respectively. Comparison between closed and open nucleus breeding systems demonstrated that open nucleus systems are superior to closed nucleus systems both in genetic and economic response. These findings therefore demonstrate that untested juvenile bucks could be an alternative to old buck strategy when economic viability of the breeding program is the main focus. There is, however, need to strike a balance between economic and genetic gains in the breeding program.