Abstract
This study aimed to phenotypically characterize indigenous Tswana sheep under its natural environment and develop prediction equations for body weight using linear body measurements in Kgatleng, Kweneng, Southern and South-East districts of Botswana. Multistage purposive sampling was used for selection of districts. Data on qualitative characters and quantitative measurements were made on 665 sheep stratified by dentition into four age categories (0PPI, 1PPI, 2PPI and ≥3PPI). Both qualitative and quantitative data were analyzed using Statistical Analysis System. Most Tswana sheep were characterized by plain coat color pattern with white dominating and plain white colors, short-fat tails with a straight tip, horizontal ears, no horns and wattles. District, sex and age had a significant influence on body weight and most linear body measurements. The highest correlation between body weight and heart girth for both sexes indicate that heart girth explained more variation than other measurements thus is the best variable for predicting body weight in both sexes. The best predicted body weight model for males is y=-64.15+1.28x and y=-53.47+1.14x for females where x and y are heart girth and body weight, respectively. This study reveals existence of diversity of sheep genetic resources across districts, indicating their potential response to selection. Key words: Body weight, characterization, morphometric traits, Tswana sheep.
Highlights
Indigenous sheep are widely distributed in the tropics and subtropics due to their unique adaptive features that enable them to fit in a wide variety of environments (Berihulay et al, 2019)
This observation is different in other part of the African continent such as Ethiopia where Hailemariam et al (2018) reported the dominance of black coat colour for Gamogofa sheep which helps in absorption of solar radiation to maintain an optimum body temperature in the cold Gamogofa zone
The fat tail is an adaptive attribute that serves as an energy reserve to enable indigenous Tswana sheep to adapt and survive feed fluctuation periods throughout the year (Ermias et al, 2002)
Summary
Indigenous sheep are widely distributed in the tropics and subtropics due to their unique adaptive features that enable them to fit in a wide variety of environments (Berihulay et al, 2019). In Botswana, the indigenous sheep constitute about 195 000 of the 300 000 national flock (Botswana Statistics, 2016) and is adapted to different geographical regions of the country. Indigenous Tswana Sheep retain certain adaptive features such as drought, heat and disease tolerance (Nsoso et al, 2004b). The major threat facing indigenous Tswana sheep genetic resources is uncontrolled breeding with exotic breeds or breed replacement with exotic breeds carried out in an endeavor to improve the breed to meet current market demands for more mutton
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