Quality of ewe milk as affected by number of lambs and length of suckling

The effects of the number of lambs, length of suckling and diet on milk yield and milk quality parameters were studied on 100 clinically healthy Comisana ewes. A medium energy level diet (MEL) of 0.93 Milk Forage Units (MFU) daily was administered to 40 ewes 6 weeks preceding lambing, while a low energy level diet (LEL) of 0.64 MFU daily was fed to 60 ewes during the same period of time. In both trials, at lambing ewes were divided into 4 groups, related to the number of lambs (single or twin) and to the length of suckling (short or long). In MEL groups, milk, total protein and casein yield were higher (P<0.05) in short suckled ewes, while single lambed ewes had a higher milk fat yield (P<0.01) and fat (P<0.01) and casein content (P<0.05), as well as better (P<0.05) clotting times and rates of clot firmness. In LEL ewes, short suckling resulted in a greater (P<0.05) milk yield, while long suckling improved (P<0.01) milk protein content. The number of lambs and length of suckling affected the Somatic Cell Count (SCC) only in LEL ewes in the first 5 weeks of post-weaning lactation. Twin lambed and long suckled ewes showed higher (P<0.05) SCC values. In both trials, long suckling lowered amino acid utilisation for milk protein synthesis, especially in twin lambed ewes. These results indicate that the number of lambs and length of suckling have a temporary effect on the SCC in ewes only when undernourished in late pregnancy. The effects on nutritional properties and renneting ability of milk persist at least over the first 3 months of post-weaning lactation.