The effect of non-genetic factors on the early body weights of Tunisian local goats

It was evaluated in this study the environmental effects on body weights of goat kids from birth to 150 days of age of Tunisian local goat population, on the basis of 1,656 records obtained from the Arid Areas Institute of Medenine, Tunisia, during 2001-2005. Except for birth weight, individual records were adjusted for standard ages (30, 60, 90, 120 and 150 days) using either extrapolation or interpolation on field data. Data were analyzed by GLM procedure and SNK (alpha = 0.05) means comparison test. The kidding year (2001-2005), kidding month (December, January, February, and March), birth type (single and twins), sex (male and female), coat colour of kid and age of dam (2-10 years) were definied as non-genetic factors. Results showed that mean values and standard deviation (SD) of body weight at birth (0), 30, 60, 90, 120 and 150 days of age were 2.57 +/- 0.52 kg, 4.06 +/- 1.16 kg, 6.99 +/- 1.87 kg, 8.90 +/- 2.46 kg, 11.48 +/- 3.35 kg and 13.53 +/- 4.80 kg for male and 2.29 +/- 0.44 kg, 4.76 +/- 1.13 kg, 3.09 +/- 1.33 kg, 8.08 +/- 2.02 kg, 10.24 +/- 2.36 kg and 12.15 +/- 6.54 kg for female. The kidding year, birth type and sex had effect on body weights of Tunisian local kids at all ages. The single and male was always heavier than the twins and the females. The birth month had effect on all body weights except for weight at 30 days of age. The age of dam had effect on body weights from 60 to 150 days of age. However, the coat color had no significant effect on all body weights. Environmental effects estimated in this study are important and need to be taken into account for Tunisian local goat management and breeding improvement under harsh conditions.