Early growth of morphometric traits of local goat population in Tunisian arid zone

Data collected during four years periodic control on 276 indigenous kids was used to study morphometric linear growth of 17 body parts under and zone pastoral conditions. The aim is to establish the kinetic of the kid's stature growing, from birth till five months age and the impact of some non genetic factors as a step of the local goat population characterization. The individual data was used to estimate, by intra or extrapolation, kids' measurements at standard ages: birth, 1, 2, 3, 4 and 5 months of age. These kid's individual performances were statistically analyzed by GLM procedure as quantitative traits. A means comparison test (SNK α = 5%), was applied to identify homogenous group for each environmental factor, such as year and kidding month. Results show that local goat population is characterized by a small size since the birth. Indeed, the height with-at-withers do not exceed 30 cin at birth and 51 cm at the 5 months age. Besides, an average 83% of kid is reached during the 5 first month of life. Since early summer, the kids' growth stagnates in relation to the environmental condition effects. GLM analysis showed that the kid's body parts vary enormously according to environmental factors acting on the range lands resources availability. The factors years and months of birth illustrate signifying impacts (p<0.01) on all kids' morphometric traits. Indeed, the remarkable inter and intra annual irregularity of the and climatic conditions largely influences the rangelands resources affecting, thus, kids and goat mother's performances. The expression of kids' genome during the growth period seems to be dependent on resources and kids requirements. The performances variability becomes considerable only after 2 month age. Such aspects supplement the characterization of the population and help to the establishment of practical selection criteria for mobile goat herds.