Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract only
Publication Acceptance Date: 3/12/2007
Publication Date: 7/8/2007
Citation: Muck, R.E., Contreras, F.E., Mertens, D.R. 2007. Silage Inoculant Effects on In Vitro Rumen Fermentation. Joint Meeting of the ADSA, AMSA, ASAS and PSA. Journal of Animal Science 85(Supplement 1):284. Interpretive Summary:
Technical Abstract: Four inoculants, B (Lactobacillus plantarum and Enterococcus faecium), C (Lactobacillus plantarum), D (Lactobacillus pentosus), E (Lactococcus lactis), were compared with an uninoculated treatment (A) on alfalfa (38% DM, AS), corn (36% DM, CS), and brown midrib corn (33% DM, BMR) silages. All inoculants were applied at 10^5 CFU/g forage. Four 1-L jars were ensiled of each treatment. Silages were analyzed for fermentation characteristics. Additionally, 100 g from each silo were wet ground (2 to 5 mm) and frozen (-20 C) until used for in vitro incubations. Two in vitro rumen fermentations were conducted per each treatment and crop. For each run, 1.0 g wet-ground silage from each silo was placed in a 160 mL serum bottle. Buffer (17 mL) and inoculum (12 mL) were added to each bottle. The bottles were sealed with butyl rubber stoppers and crimps and incubated at 39 C. Gas pressure was measured at 3, 6, 9, 24, and 48 h. At 9 and 48 h each treatment was analyzed for microbial biomass yield (MBY) and volatile fatty acids (VFA). Silage pH and lactic acid concentration were not affected by treatment across three trials. Silage pH was higher on AS (4.60) than CS (3.84) and BMR (3.89). Lactic acid concentration was similar between AS (74 g/kg DM) and BMR (73), but greater than CS (45). At 9 h incubation, gas and VFA production were different among crops (P < 0.05) but not among treatments (P > 0.05). However, MBY differed across treatment and crop. MBY in CS was similar to AS and greater than BMR (39.5, 39.3 and 32.7 mg/100 mg truly digested (TD) respectively). Among inoculants, C, D, and E (37.9, 39.0, and 38.0 mg/100 mg TD respectively) were similar and greater than A and B (35.4 and 35.5 mg/100 mg TD respectively). Similar trends in MBY were observed at 48 hr incubation. We conclude that the biggest impact of silage microbial inoculants on in vitro rumen fermentation was increasing microbial biomass yield, but this effect was not equal across all microbial inoculants.