Genetic improvement of small ruminants in low-input, smallholder production systems: Technical and infrastructural issues☆
Introduction
Small ruminants (i.e., sheep and goats), especially indigenous breeds, are widespread and important to the subsistence, economic and social livelihoods of a large human population in developing countries (Kosgey, 2004). These animals have lower feed and capital requirements than larger species, making them suited to smallholder producers (Devendra, 2002). They also have shorter generation intervals, higher prolificacy, small size, and are better able to utilize a wide range of feedstuffs, including crop residues that are of little value otherwise (Holst, 1999, Pelant et al., 1999). In Africa and Asia, population of small ruminants is increasing due to their better adaptation to the prevailing conditions and suitability to small-scale farms (FAO, 2004). Despite the large numbers and importance of small ruminants in developing countries, information on sustainable genetic improvement programs under smallholder production circumstances is scarce, especially for the adapted indigenous breeds (Kosgey et al., 2006). Few studies have addressed the technical and infrastructural issues pertaining to sustainable genetic improvement programs in these systems. This paper focuses on these two issues. First, to provide the context, the salient features of low-input, smallholder production systems are highlighted.
Section snippets
Smallholder production systems
Smallholder production systems comprise sedentary farmers, each with small parcels of land, in which they practice mixed (crop and livestock) farming (Kosgey et al., 2006). In the developing world, mixed farming systems are mainly found in the agriculturally medium to high potential areas. In some instances, households live in marginal areas or are landless. The latter have to rely on public or other people's land (Pelant et al., 1999). Approximately 64% of the world's small ruminants are kept
Overview of genetic improvement programs
The main pathways for genetic improvement of livestock are: (i) selection within breeds (populations); (ii) selection between breeds (populations); and (iii) crossbreeding. Crossbreeding could embrace upgrading for breed substitution, formation of synthetics or systematic terminal and rotational crossing. Detailed discussion on the application of these methods have been presented by Ponzoni (1992), Baker and Gray (2004) and Kosgey (2004) and will not be discussed further here.
In designing new
General discussion and conclusions
There is great potential for small ruminants to contribute more to the livelihoods of people in low-input, smallholder production systems. To achieve that, efficient and sustainable genetic improvement programs are required to boost output and profitability, and meet the peoples’ needs for the animal products. Yet the over-riding conclusion of this review is that genetic improvement is but one component of what has to be an integrated approach to enhancing the productivity of small ruminants,
Acknowledgements
We gratefully acknowledge the International Livestock Research Institute (ILRI, Nairobi, Kenya) and Egerton University (Njoro, Kenya) for provision of facilities and support.
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This paper is part of the special issue entitled “The Outlook of Quantitative and Molecular Genetics Applications in Improving Sheep and Goats” guest edited by David Notter, R. Leyden Baker and Noelle Cockett.