Assessment of the main factors affecting goat milk yield and composition in the North West region of Tunisia

This study aimed to assess the main factors affecting goat milk yield and composition from the Northwest region of Tunisia. A survey and a sampling campaign were conducted over four months (February-May, 2018), within 112 farms in 3 regions. Individual daily milk yield (DMY) was registered and milk samples were taken in duplicate to be analysed for fat (FC), protein (PC), solid not fat (SNF), density and lactose contents. Results showed that the Alpine breed allowed the highest DMY and PC, and the Damasquine presented the highest FC. The third lactation allowed the highest DMY (0.95 Lday-1) and FC (6.68%), however the highest PC, SNF and density are recorded for primiparous. Concerning the birth weight of kids, DMY increased significantly with the weight of the kids at birth, and it resulted in a significant effect on the FC. The assessment of the region effect showed that the highest DMY was obtained in the region of Jendouba and Ghardimaou. For milk composition, when breed effect was eliminated and focused only on the local breed, we found the highest FC in Sedjnen/Nefza. The analysis of the goat feeding allowed identifying 5 types of rations. Also, statistical analysis showed that the highest DMY resulted from the rations T4 and T5 (averaged 1.06 Lday-1). No effect of ration type on FC and density was found. Concerning PC, SNF and lactose, the ration effect had no significant effect, but a trend of highest values was noted for T3. It was concluded that dairy performances were low, focusing only on the local goat population. However, the produced milk is of good quality regarding the determined chemical composition. Indeed, there is a negative correlation between milk production and the chemical composition of milk. Substantial improvements are potentially possible through actions (improvement of the quality of the ration, milk hygiene, milk collection pattern, training of breeders, etc) to develop a value chain in the region and improve farmer incomes.