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Journal of Agronomy
  Year: 2007 | Volume: 6 | Issue: 1 | Page No.: 61-67
DOI: 10.3923/ja.2007.61.67
 
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Growth Model Adjustment of Local Goat Population under Pastoral Conditions in Tunisian Arid Zone

S. Najari , A. Gaddoun , M. Ben Hamouda , M. Djemali and G. Khaldi

Abstract:
Kids weights recorded from eight indigenous goatherds raised under arid pastoral conditions were used to characterise kid’s growth curve. Among twelve tested non-linear models, Gompertz function permitted the best kids growth curve fitting by its convergence rapidity and estimation accuracy. Models iterative behaviour were tested by the iterations number, the Coefficient of Determination (CD) and the Residuals Means Squares (RMS). Convergence was reached after 9 iterations at a CD equal to 67%. Indigenous kids weighed 2.41 kg at birth and reached 16.18 kg in 8 months of age with a wide individual variation. Kid’s growth showed stagnation at the summer beginning, due to climate stress and forage scarcity. During the first 4 months of age, the daily weight gain reached 102 g/day as a maximum average and then, decreased to less than 25 g/day. About 80% of asymptotic weight was reached since the 4 months of kid’s age. Kid’s early separation from pastoral herds was recommended to reduce land degradation and to allow better reproduction performances. The indigenous kid’s growth process illustrates the adaptation of the population with the arid environment under natural harsh conditions. Small body size and low weights mean fewer requirements and may permit to reach rapidly the physiological maturity needed to start the reproduction process despite of the constraining arid conditions.
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How to cite this article:

S. Najari , A. Gaddoun , M. Ben Hamouda , M. Djemali and G. Khaldi , 2007. Growth Model Adjustment of Local Goat Population under Pastoral Conditions in Tunisian Arid Zone . Journal of Agronomy, 6: 61-67.

DOI: 10.3923/ja.2007.61.67

URL: https://scialert.net/abstract/?doi=ja.2007.61.67

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