In Situ Digestibility and Nutritive Value of Inoculated Cool-Season Annual Grass Baleage

Abstract

Baleage provides a method to store high quality forages in less-than-ideal Southern weather patterns. The current study evaluated forage nutritive value, in situ digestibility, and silage inoculation of baleage from four cool-season annual grasses: rye (RY: Secale cereale L.‘Wrens Abruzzi’), triticale (TR: ˟ Triticosecale Wittmack ‘NCPT01-1433’), wheat (WT: Triticum aestivum L.‘SRW8340 croplan’), annual ryegrass (AR: Lolium multiflorum Lam. ‘Jumbo’). Baleage was randomly selected as not inoculated or inoculated using a silage inoculant containing Lactobacillus buchneri, L. plantarum, and Enterococcus faecium that was applied after wilting to 50% moisture content. The forages were then ensiled in laboratory mini silos for 296 ± 1 days. Forage nutrient values were evaluated by near infrared reflectance spectrometry (NIRS), additionally, dry matter disappearance and neutral detergent fiber (NDF) were evaluated using the in situ method using two ruminally-fistulated beef heifers. Among baleage treatments, WT was the most valuable as a stored forage. Wheat contained the greatest crude protein, non-fiber carbohydrates, ethanol soluble carbohydrates, water soluble carbohydrates, total digestible nutrients, net energy lactation, net energy maintenance, net energy gain, and metabolizable energy (P < 0.0001). In addition, WT was lowest in acid detergent fiber (ADF), NDF, and lignin (P < 0.0001). In contrast, RY was the least valuable as a conserved forage. Rye was greatest in ADF, NDF, lignin, and the least in total digestible nutrients, net energy lactation, net energy maintenance, net energy gain, and metabolizable energy than the other forages (P < 0.0001). Inoculation status did have a significant effect in that, inoculated forages were greater in pH (P = 0.0038), ash (P= 0.0106), magnesium (P = 0.0047), and calcium (P = 0.0003) concentrations than non-inoculated forages. Non-inoculated forages had a greater effect on TDN (P = 0.0356), ESC (P= 0.0004), WSC (P < 0.0001), and metabolizable energy (P = 0.0398) than inoculated forages. Inoculated forages post 40 h in situ provided a greater effect on digestion than non-inoculated. In situ results provided RY and TR had a greater (P = 0.0407) potentially digestible fraction while WT had the lowest undegradable fraction (P < 0.0001). Inoculated forages were greater in the potentially digestible fraction (P = 0.0075), and lower in the undegradable residue (P = 0.0136). In conclusion, rye did not show value for livestock or a producer to conserve as baleage. Triticale, AR, and WT show promise to conserve as baleage to provide a highly nutritious stored feedstuff for cattle. Inoculant use needs further research, but the inoculant did provide positive in situ animal digestibility results.