MORPHOMETRIC CHARACTERISATION AND IMPROVEMENT OF POTENTIAL GROWTH TRAITS IN WAD SHEEP THROUGH CROSSBREEDING
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Date
2018
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Abstract
The need for larger sheep has compelled both the consumers and sellers in the middle and
Southern parts of Nigeria to frequently opt for giant breeds of sheep from the Northern parts
of the Country. Balami and Uda are the two largest Nigerian breeds of sheep and therefore
have the potentials of improving, through crossbreeding, the body weight of small body-sized
West African Dwarf (WAD) sheep. The objectives of this study were to determine: (i) the
morphometric characteristics of traditionally managed WAD, Balami and Uda sheep; (ii)
reproductive and growth performance of pure and crossbred sheep; (iii) heterosis,
repeatability and heritability of economic traits; and (iv) best morphometric descriptors of
body weight in pure and crossbred WAD, Balami and Uda sheep in Nigeria.
Three experiments were conducted. Experiment 1 compared the morphometric traits of 1017
traditionally managed sheep within North and Central Nigeria. Experiment 2 evaluated the
growth and reproductive performance of pure and crossbred Uda, Balami and WAD Sheep
using an unbalanced design, while Experiment 3 assessed the heritability and repeatability of
growth traits and best morphometric descriptors of pure and crossbred sheep. Data collected
were subjected to Analysis of Variance using a model of Factorial Design (p˂0.05).
The findings of the study were that:
i. traditionally managed Balami sheep was superior to Uda and WAD in all
morphometric traits. Males were superior to females in all morphometric traits.
ii. WAD sheep had the highest conception (80%) and lambing rate for all the parities
(80%);
iii. lambs’ birth weights increased with dams’ age and parity;
iv. crossbred lambs were superior over purebred WAD in all morphometric traits both at
birth and at yearling stages;
v. heterosis for body weight in Uda crossed with WAD was higher than in Balami
crossed with WAD at birth (24.70% and 22.42% respectively) and at weaning (9.25%
and -4.84% respectively);
vi. WAD had higher repeatability for body weights (0.99) and total milk yield than other
breeds; and
vii. WAD sheep group had the most accurate classification (92.4%). The Dendogram plot
showed WAD sheep was closer to Uda than Balami while Uda crossed with WAD
sheep was closer in body weight to the purebred Uda sheep.
The study concluded that genetic resources of Nigerian breeds of sheep could be described
using morphometric traits. Crossbred sheep were superior to the purebred WAD sheep in
morphometric traits, lamb birth and weekly body weights. The study recommended that to
improve weaning weight, Uda sheep should be crossed with WAD sheep. However, to
improve yearling weight, Balami sheep should be crossed with WAD sheep.