Effect of silage additives on in vitro forage digestion and performance of cattle fed four different silages

Abstract

Temperate corn silage is often produced, but increased land utilization may occur if heat and drought resistant alternative forages are ensiled during late summer and autumn for use as primary feeds for growing beef and dairy cattle. Our objectives were to determine the effects of inoculant and additive treatments on chemical composition and fermentation characteristics of temperate corn (CS), pearl millet (PM), tropical corn (TC), and sorghum (S) silages; and, the effects of silage type and inoculant treatment on intake, gain and digestibility of the silages fed to growing beef cattle. All silages were low in DM, and inoculants did not uniformly improve fermentation or digestibility of silages. Extremely low concentrations of lactic and malic acids were observed for PM compared with other silages. Chemical and fermentation data indicated that addition of corn grain at ensiling improved fermentation on TC, PM and S silages. In vivo digestibility was highest for CS and lowest for PM; however, when the four silages with Sun-Cure inoculant were supplemented with energy and protein similar OM, ADF and NDF digestion of total mixed diets was observed. Feedlot results indicated that cattle had lower DM intake (P < 0.07) and lower daily gains (P < 0.01) on PM compared with CS when fed silages with energy and protein supplements. Inoculation with Sun-Cure did not improve cattle performance. Results indicate that PM silages are lowest in digestibility, and that substantial amounts of energy supplementation may be required to elevate cattle performance to comparable levels with CS.