Twin or single-bearing ewes may produce insufficient colostrum for their lambs even when grazing lush green pastures. Consequently, a supplement of grain in late pregnancy provides the ewe with a more concentrated diet and can overcome the limitations imposed by roughages alone.
Scientists from Uruguay and Australia tested the hypothesis that short-term feeding of barley just before lambing would be as effective as corn in stimulating early production of colostrum. They believe that it is the starch supplied by both both grains that is the key to stimulating the production of colostrum.
Fourteen days before the expected time of lambing, 35 Corriedale ewes bearing single fetuses and 25 ewes bearing twin fetuses [from a synchronized mating] were allocated to three treatments and fed (1) a basal diet of alfalfa hay to meet their nutrient requirements; (2) the basal diet plus a supplement of whole barley; and (3) the basal diet plus a supplement of cracked corn.
Following injections of oxytocin, milk samples were collected from one teat of each ewe at 0, 1, 3, 6, and 10 hours after lambing. The colostrum was weighed and classified. A 20 ml sample was analyzed for its components. Lambs were allowed to suckle from the other uncovered teat.
Supplementation of the ewes prior to lambing did not affect the birth weight of their lambs. Supplementing ewes before lambing either with whole barley or cracked corn increased the quantity of colostrum accumulated at birth and its subsequent secretion during the following hours.
Supplemented ewes produced between 1.9 to 2.8 times more colostrum at birth than unsupplemented ewes, despite the unsupplemented ewes being fed to meet their estimated metabolizable energy requirements. Supplemented ewes not only produced more colostrum than unsupplemented ewes, but the colostrum they produced was less viscous, thus easier for the lambs to ingest.
In the single-bearing ewes, barley was less effective than corn in increasing the amount of colostrum produced, but it was just as effective in twin-bearing ewes.
Source: Animal. May 2007.