Effects of Genotype-Environment Interaction upon Local Goat Dairy Production in the Tunisian Oases

Dairy data harvested during 16 years in a goat herd composed by local goat, Alpine, Damascus, Murciana and 6 crossed groups was used in the present study. The aim is to establish the effects of genotype-environment interaction upon goat milking potentialities under oasian husbandry conditions. For each goat, total production per lactation (Kg), daily average (kg day 1) and milking period (days) were estimated by Fleischmann method. A GLM Procedure was applied to identify the interactive effects of genotype towards the year and the kidding mode, respectively. Analysis show the milk production per lactation varies differently both with genetic groups and the year of kidding. Among pure breeds the productive behaviour for each group depends largely to the year. For example, the Alpine production varied between 329 kg during 179 days and decreased to 217 kg during the year 1990/1991. The kidding mode effect seems not similar for all genetic groups, especially among crossed genotypes. Results allow to conclude that the oasian environment modulate largely the dairy potentialities of caprine genetic groups. Some genotypes have more regular performances than other subjected to the same conditions. Such interactive effect should be considered to organise genetic improvement program.