Abstract:
Small ruminants (i.e., sheep and goats) are widespread in the tropics and are
important to the subsistence, economic and social livelihoods of a large human
population in these areas. The aim of this thesis was to identify the breeding
objectives for tropical small ruminants, and to develop appropriate breeding
strategies for their improvement. The results indicated that breed substitution and
crossbreeding programmes involving temperate breeds are rarely successful due to
incompatibility of the genotypes with the farmers’ breeding objectives and the
production systems. Within-breed selection programmes utilizing indigenous breeds
are likely to be more sustainable than breed substitution and crossbreeding. In
addition,
they
help
to
maintain
biodiversity.
Indigenous
genotypes
were
predominantly found among pastoral/extensive farmers and mixed crosses among
smallholders. In general farmers perceived crosses less favourably than indigenous
breeds for a range of traits. The effect was studied of including intangible benefits in
the calculation of economic values of breeding goal traits. It resulted in increased
values of traits related to longevity. Litter size and lambing frequency were more
important traits in smallholder and pastoral production. 12-month live weight also
featured prominently in pastoral production. Constraints to small ruminant
productivity included low levels of management, disease and parasite challenge,
inadequate feed and poor marketing. Nucleus breeding schemes are recommended
to optimize the limited available resources. However, ‘interactive cycling screening’
schemes would be more practical under village settings as the farmers are actively
involved in genetic improvement, and minimal recording is required in the commercial
flocks. A single nucleus could serve both the smallholder and pastoral production. In
conclusion, it is prudent to examine the production system holistically, and involve
the producer at every stage in the planning and operation of a breeding programme,
integrating traditional knowledge, practices, behaviour and values.
