Nutrient Losses, Quality, and Feeding Values of Wilted and Direct-cut Orchardgrass Stored in Bunker and Tower Silos

l~irst-cutting orchardgrass was preserved as: 1. Wilted silage stored in a tower silo.2. Direct-cut, sodium metabisulfite-treated silage, stored in a tower silo.3. Direct-cut sodium metabisulfite-treated silage, stored in a bunker silo.These silages were prepared in each of two successive years and all silages were sealed with weighted plastic covers.The silages were compared on the basis of storage losses, storage temperatures, chemical quality, feeding trials, and digestion trials.An expression of silage feeding value which eombines dry matter intake rate and TDN content has been proposed.Tower storage of wilted forage and bunker storage of the direct-cut forage were about equally efficient in preserving feed nutrients.Tower storage of direct-cut forage was consistently less efficient, primarily because of higher seepage losses.All silages were of good chemical quality and of about equally high feeding value.The wilted silage, however, contained more butyric acid in both years and was consumed by dairy cattle in significantly greater amounts one year.The bunker silo, as used in this experiment, was a more suitable storage structure for direct-cut orchardgrass than a tower silo.However, when forages were stored in tower silos, the wilting method was generally more satisfactory than direct-cutting emubined with sodium metabisulfite treatment.Difficulties in obtaining well-preserved and palatable silages from direct-cut, high-moisture hay crops have been repeatedly although not consistently observed.Mitigation of these problems by wilting the crop, as demonstrated by Woodward and Shepherd (11), has been reported by the Vermont and Ohio workers (8, 9), as well as by numerous other investigators.Wilting is now one of the generally accepted ensiling procedures.Improved preservation and/or increased palatability by the use of sodium metabisulfite applied to the unwilted silage has also proven beneficial under some conditions (1, 2, 5).Although both of these procedures have produced some beneficial effects, few direct comparisons between the two methods have been reported.A direct comparison of this type, reported by Cowan et al. (2), indicated a marked advantage of bisulfite treatment over wilting for the dry matter preservation of pre-bloom and full-bloom alfalfa, but no advantage for 1/10-bloom alfalfa.However, these results may not provide a practical comparison of methods, since the silages were made in 4-by 8-ft.silos, and dry matter losses of up to 35% were observed in the wilted silage.Other investigations (10, 11), using farm-sized silos, have reported losses of about one-third this amount from wilted silage.