Ratoon Cropping Forage Sorghum for Silage: Yield, Fermentation, and Nutrition

Two field experiments were conducted on Lexington silt loam soil (fine‐silty, mixed, thermic Typic Paleudalf) to identify a harvest regime that would improve the nutritive value of ensiled whole‐plant sorghum [ Sorghum bicolor (L.) Moench] while maintaining silage yield. In a 1‐yr preliminary study, first‐cut sorghum was harvested at mid‐vegetative, late‐vegetative, boot, bloom, and hard‐dough stages of maturity. Regrowth was harvested in late August. In a 2‐yr experiment, yield, ensiling losses, intake, and in vivo apparent digestibility of vegetative sorghum (initial and ratoon cute wilted 24 h) were compared with direct cut hard‐dough‐stage sorghum. Forages were stored in 1.8‐Mg‐capacity (fresh wt.) experimental silos and, upon opening, were fed to lambs ( Ovis aries }. Results from the preliminary experiment indicated that dry matter (DM) yield of first‐cut sorghum was greatest at the hard‐dough stage; however, nutritional value was greatest for the mid‐vegetative stage. Maximum yield for the combined harvests was obtained when first harvest was made at boot stage. The 2‐yr experiment average DM yields were 7.3 Mg ha −1 for combined initial (mid‐vegetative stage) and ratoon crops, compared with 6.7 Mg ha −1 for the single hard‐dough‐stage harvest. Ensiling fosses did not differ with harvest regime. Vegetative sorghum was more digestible than sorghum harvested at the hard‐dough stage (670 vs. 570 g kg −1 ). These studies suggest that sorghum harvested twice per season (with wilting) will produce a higher quality silage than a single hard‐dough stage cutting, without yield reduction