The yield and composition of the milk of Finnish Landrace x Blackface ewes: I. Ewes and lambs maintained indoors

Twenty-two Finnish Landrace x Blackface ewes suckling either single, twin, triplet or quadruplet lambs were maintained indoors during a 12-week lactation period. Milk production was estimated at weekly intervals by hand milking following oxytocin administration. Milk was collected from each ewe in four similar volumetric portions which were retained in order of withdrawal and analysed for major constituents. Weighted volumes of milk from each of the four portions were bulked to give a single sample for analysis. Estimated mean total milk production over a 12-week period from parturition was 134, 205, 212 and 218kg for single-, twin-,triplet- and quadruplet-suckled ewes respectively. Most of the difference in total yield between multiple-suckled groups of ewes occurred during the first 3 weeks of lactation, and the data indicate that the number of lambs born, or the total weight of concepta, influences the initial quantity of milk available to the lambs. Regression analysis showed significant evidence for difference between the linear components of the regression of milk yield, fat, protein, lactose and Gross Energy on the stage of lactation for all suckling groups. The concentration of all constituents other than lactose and ash was higher in colostral milk, but was significantly higher only in respect of fat, protein and Gross Energy. Substantial differences found between suckling groups in respect of fat and protein content of the milks indicate an influence on these constituents due to the number of lambs suckled. The mean growth rates of the triplet- and quadruplet-suckled groups of lambs were each significantly lower than each of the single- and twin-suckled groups. The food intake of the ewes in relation to shape of lactation curves and consequent lamb growth is discussed.