Effect of ensiling time and hybrid type on fermentation profile, nitrogen fractions, and ruminal in vitro starch and neutral detergent fiber digestibility in whole-plant corn silage

Abstract

ABSTRACT The objective of this study was to evaluate the effect of ensiling time and hybrid type on fermentation profile, N fractions, and ruminal in vitro starch (ivSD; 7 h) and NDF (ivNDFD; 30 h) digestibility in whole-plant corn silage (WPCS). Samples from 8 hybrids [4 leafy (LFY) and 4 brown midrib (BMR)] were collected at harvest, vacuum-sealed in plastic bags, and ensiled for 0, 30, 120 and 240 d. Starch and DM concentration were unaffected (P > 0.10) by ensiling time or hybrid type. Ethanol concentration and pH were greater (P = 0.01) for LFY than BMR, but lactate and acetate did not differ (P > 0.10). Soluble-CP concentrations tended (P = 0.09) to be greater for LFY than BMR, but ammonia-N and ivSD concentrations were unaffected (P > 0.10) by hybrid type. Measurements of lactate, acetate, and total VFA concentrations were greater (P 0.10) by ensiling time. Positive relationships between ivSD and ammonia-N or soluble CP were observed (P = 0.001). Fermentation profile, ammonia-N, soluble CP, and ivSD were greatly influenced by ensiling time but minimally by hybrid type. The ivNDFD was affected by hybrid type but not ensiling time. Ammonia-N and soluble CP were good indicators of ivSD in whole-plant corn silage.