Proposed genetic improvement strategies for dairy cattle in Kenya

Abstract

<p>Genotype by environment interactions and heterogeneity of variance may influence the effectiveness of breeding programs in developing countries. This study investigated optimization of dairy cattle breeding programs within Kenya for low, medium and high input and output production systems in the presence of genotype by environment interactions. Multi-trait selection index theory was applied using the SelAction software package to determine the optimum strategy that would maximise genetic gain across the three production systems. The breeding goal was to maximise overall gain for a breeding objective containing three traits: lactation milk yield; lactation fat yield and calving interval. Three selection strategies based on: 1) sire evaluation and selection within the high production systems only (<i>single</i>); 2) independent sire evaluation and selection within each production system (<i>independent</i>) and 3) sire evaluation across all production systems (<i>joint)</i>, were evaluated under scenarios using progeny test information and genomic information. The joint strategy maximised the overall economic gain (1583 Kes) while the single strategy generated the least overall gain (1311 Kes). The dairy industry in Kenya would therefore benefit from implementing production system specific breeding strategies for bull evaluation and selection. In addition, implementing genomic selection could speed up the rate of genetic gain compared to progeny testing due to reductions in generation interval and higher selection accuracy with a moderately large reference population.</p>