A review of the effects of molasses treatment of unwilted grass at ensiling on silage fermentation, digestibility and intake, and on animal performance

The published literature on the effects of molasses as a silage additive to unwilted grass was reviewed. The aspects considered include silage fermentation, additive and ensiling losses, digestibility and intake, and performance of lactating dairy cows and of growing and finishing beef cattle. The effects of formic acid, when used in the same studies as molasses, were also reviewed. Relative to untreated silage, treatment with molasses improved (P < 0.001) silage preservation and increased (P < 0.01) intake but did not significantly alter digestibility or animal performance. In direct comparisons of formic acid, molasses and no additive, additive treatment improved (P < 0.01) silage preservation and increased (P < 0.05) intake but did not significantly alter silage digestibility. In these same comparisons, formic acid increased (P < 0.01) animal performance whereas molasses had no effect. Compared with molasses, formic acid improved silage preservation, by decreasing (P < 0.01) pH and ammonia N concentration, and improved (P < 0.01) animal performance. There was no relationship between rate of molasses applied and silage fermentation characteristics, intake, digestibility or animal performance. It is concluded that the addition of molasses to unwilted herbage at ensiling improved silage fermentation and increased intake but had no effect on animal performance. Formic-acid treatment improved silage fermentation and intake and increased animal performance.