The effect of the foaling season on lactation length and milk production of jennets

The effects of the foaling season and the lactation phase on the milk productive variables were investigated on 34 pluriparous jennets fed with hay, concentrate and pasture. From the 21st post-foaling day, the jennets were manually milked without the foal, one time a day, after 5 hours from the foal' separation. Every 3 weeks, the individual milk yields were recorded and individual milk samples were collected and analyzed. The foaling season influenced the jennets' length of lactation (P<0.001). In general, the jennets foaled in spring and in summer showed longer lacta- tions, in relation to the climatic conditions in which the animals evolved the different lactation stages. However, the total milk produced in the lactation did not show differences, because of the jennets foaled in summer, with the lowest daily milk yield, showed the longest lactations. The foaling season influenced the fat (P<=0.05), the protein (P<=0.001) and the lactose contents (P<=0.001), as the somatic cell score (SCS) (P<=0.001). The daily milk yield of the jennets foaled in spring, in summer and in win- ter showed an evident peak in the first lactation phases, differ- ently of the jennets foaled in autumn. After the aforementioned times, the daily milk yield decreased until the end of the lacta- tion. The fat trend would seem influenced by the forage availabil- ity. In agreement with the normal lactation tendency, a higher protein content were found in the first lactation phases, decreas- ing during the lactation. The lactose content increased apprecia- bly until the 150th day and after decreased. If one milking in a day is adopted, it would seem convenient to milk the jennets until 8- 9 months post foaling.