Joint genetic analysis for dairy cattle performance across countries in sub-Saharan Africa

O Opoola,G Banos,G Simm,M.G.G Chagunda,C.B Banga,J.M.K Ojango,L.M Beffa,R Mrode

doi:10.4314/sajas.v50i4.3

Abstract

This study assessed the feasibility of across-country genetic evaluation of dairy cattle in sub-Saharan Africa where data on livestock production are scarce. Genetic parameters were estimated for the 305-day milk yield in the first lactation and across five lactations, for age at first calving and for interval between first and second calving. Estimated breeding values of individual animals for these traits were calculated. There were records from 2 333, 25 208, and 5 929 Holstein cows in Kenya, South Africa, and Zimbabwe, and 898 and 65134 Jersey cows from Kenya and South Africa. Genetic gain from sire selection within and across countries. was predicted Genetic links between countries were determined from sires with daughters that had records in two or more countries, and from common ancestral sires across seven generations on both the maternal and paternal sides of the pedigree. Each country was treated as a trait in the across-country evaluation. The results showed that genetic variance and heritability were not always estimable within country, but were significantly different from zero in the across-country evaluation. In all three countries, there was greater genetic gain in all traits from an across-country genetic evaluation owing to greater accuracy of selection compared with within country. Kenya stood to benefit most from an across-country evaluation, followed by Zimbabwe, then South Africa. An across-country breeding programme using joint genetic evaluation would be feasible, provided that there were genetic links across countries, and would provide a platform for accelerated genetic progress through selection and germplasm exchange between sub-Saharan African countries.Keywords: across-country genetic evaluation, genetic connectedness, genetic progress

Highlights

Genetic improvement of dairy cattle in sub-Saharan Africa has been driven mainly by the importation of foreign breeds for pure breeding and crossbreeding with indigenous breeds (Chagunda et al, 2015)
The objectives of the study were i) to calculate and compare within- and across-country genetic parameters for production and reproduction traits using data from Kenya, South Africa and Zimbabwe; ii) to estimate and compare the breeding values of individual animals from within- and across-country genetic evaluations; and iii) to quantify the predicted genetic gains from sire selection based on these genetic evaluations
Performance and pedigree data were obtained from key livestock recording organizations in the three countries, namely the Agricultural Research Council (ARC) in Pretoria, South Africa, Kenya Livestock Breeders Association (KLBA), Kenya, and the Livestock Identification Trust (LIT) in Harare, Zimbabwe

Summary

Introduction

Genetic improvement of dairy cattle in sub-Saharan Africa has been driven mainly by the importation of foreign (exotic) breeds for pure breeding and crossbreeding with indigenous breeds (Chagunda et al, 2015). Breeds that are used for dairy production are sourced as live animals or as semen, mainly from USA, Canada, Europe, Australia and New Zealand (Maiwashe et al, 2006). Holstein is the most common exotic breed for milk production in sub-Saharan Africa (Banga, 2009), followed by Jersey, Ayrshire and Guernsey. Most countries of sub-Saharan Africa do not have clear breeding programmes to support dairy production owing to the lack of national livestock performance monitoring databases (Rege et al, 2011; Ojango et al, 2017).

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