Production characteristics, management practices and on-farm phenotypic characterisation of indigenous Tswana sheep in four districts of southern Botswana

Abstract

In the framework of collecting information that will aid in development of breeding and conservation strategies and policies intended for the conservation of indigenous Tswana sheep in the Southern part of Botswana, a survey of production system and on-farm phenotypic characterization of indigenous Tswana sheep were undertaken in the Kgatleng, Kweneng, SouthEast and Southern districts. Multi-stage purposive and random sampling were employed as sampling techniques. Detailed structured questionnaires on farmers’ socio-economic parameters, breeding and general management practices on Tswana sheep, field observations of animals, body measurements and secondary data collection were used to produce the data. Data on qualitative characters and quantitative measurements were made on 665 sheep stratified by dentition into four age categories of zero permanent pair of incisors (0PPI), one permanent pair of incisors (1PPI), two permanent pairs of incisors (2PPI) and three or more permanent pairs of incisors (≥3PPI) to represent age ranges of 6-11, 12–24, 25–36 and above 36 months, respectively. Qualitative survey data were analyzed using procedure frequencies of Statistical Package for Social Sciences while quantitative data were analyzed using Statistical Analysis System. Results revealed that the mean average flock sizes for Kgatleng, Kweneng, Southern and South-East were 22.20±3.8, 24.81±3.56, 30.08±3.77 and 23.58±3.77, respectively. Sheep played multifaceted roles for farmers across districts. Amongst the reasons for keeping sheep, Kgatleng and Kweneng district farmers primarily kept sheep for generating cash derived from sales (index= 0.480 and 0.390, respectively) and in the Southern and South-East districts farmers primarily kept sheep for ceremonial (socio-cultural) use (index=0.310 and 0.371, respectively). Competitive superiority of indigenous Tswana rams over their exotic counterparts in terms of survival and reproduction under Botswana environment was the most preferred trait when selecting breeding rams in Kgatleng ( index= 0.290), Kweneng ii (index= 0.301) and South-East ( index= 0.247) while in Southern district breeding rams were mainly selected based on body size (index= 0.372). Castration of rams in Kgatleng, Kweneng and South-East districts was mostly done at 3-6 months while Southern district farmers castrated at a later age of 6-12 months. The dominant coat color pattern on Tswana sheep was plain with most sheep having white dominant and plain white color coats. Most Tswana sheep had a characteristic feature of short fat tail with a straight tip, no wattles, no horns and almost all sheep (98.65%) had horizontal ear orientation. District, sex and age and the age by sex interaction had a significant (P < 0.05) effect on body weight and most linear body measurements. The body weight and most linear body measurements of sheep increased gradually as the sheep advancement in age. Tswana males were generally heavier and superior than females in most linear body measurements. Indigenous Tswana sheep from the Southern district showed superiority in some features of economic importance such as body weight, body length and heart girth over other districts. The overall mean body weight, heart girth, body length, wither height, rump width, ear length, tail length, tail circumference, head length, head width, shoulder width, cannon bone length, cannon bone circumference, neck length, rump length, rump height and scrotum circumference (in males) across districts were 35.93±0.55 kg, 78.31±0.65, 62.17±0.53, 64.51±0.51, 15.98±0.20, 11.43±0.12, 21.67±0.63, 12.54±0.57, 13.15±0.13, 10.00±0.11, 21.79±0.33, 15.19±0.12, 7.51±0.52, 30.38±0.43, 23.56±0.28, 64.44±0.31 and 26.66±0.89 cm, respectively. There were positive and significant correlations observed between body weight and most linear body measurements for both sexes. The highest correlation coefficient was found between body weight and heart girth for both sexes of Tswana sheep. The regression analysis to predict body weight from linear body measurements indicated that body weight prediction could be more iii accurate when more than one independent variable was used. However, from a practical view point, the use of heart girth as a sole predictor for body weight was suggested since heart girth accounted for more variability than other linear body measurements for sexes and also due to its ease of measurement under farmers’ conditions. The prediction of body weight for Tswana sheep was therefore based on the regression equations y= -64.15+1.28x in males 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 which needs to be verified at a molecular level.