A study of the milk yield of three strains of Scottish Blackface ewes in two environments

Milk yields of three strains of Scottish Blackface ewes (Lewis, Lanark and Newton Stewart) were recorded over periods of eight weeks on reseeded pasture and on hill pasture. There were no differences in milk yields between strains in the respective environments, but there were significant differences between environments in all three strains. Relationships between udder width and milk yield were investigated in the Lewis and Newton Stewart strains. Analyses of milk samples (taken by hand) showed there were no significant differences in the contents of fat or solids-not-fat. There was evidence that the percentage of fat and solids-not-fat in all groups tended to decrease initially and then to increase gradually as lactation advanced. Live-weights of the ewes were compared and it was shown that the Lewis ewes were characteristically lighter than either of the other strains. On the reseed all lambs were approximately equal in live-weight and condition. On the hill the Lewis lambs were inferior in weight and condition, and it is suggested this reflected the Lewis strain ewes' grazing preferences for higher ground.