Influence of hydrolyzed soybean meal on glycogen production by mixed ruminal microbes

Authors: Hall, Mary Beth; Sullivan, Michael

Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Increasing the supply of degradable protein can alter products formed by mixed ruminal microbes, decreasing glycogen and increasing microbial nitrogen. The objective of this study was to evaluate the effect of supplementing supernatant (SUP) from enzymatically hydrolyzed soybean meal (SBM) on glycogen production by mixed ruminal microbes. SBM (20% solids with distilled water; dH2O) with (+e) or without (-e) ENZECO Protease BL was incubated with continuous mixing for 1 h at 60°C. SUP was isolated by centrifugation at 15,000 x g for 10 min at 5°C. SUP N mg/mL were -e: 5.87 and +e: 13.31. Replicate in vitro fermentations (3) were performed with Goering-Van Soest medium without tryptone. Each tube contained 20 mL medium, 1 mL reducing solution, 79.5 mg glucose in 0.5 mL, 1 mL of tryptone solution or 0.2, 0.4, or 0.6 mL of SUP brought to 1 mL with dH2O, and 5 mL of strained rumen fluid. Increasing SUP delivered N mg/tube of 1.17, 2.35, and 3.52 for -e, 2.66, 5.32, and 7.99 for +e, and 2.66 or 5.32 for tryptone. -e gave insight to the impact of SUP carbohydrate addition from SBM. Tubes harvested at 3 h of fermentation were analyzed for microbial glycogen. Data were analyzed as a randomized complete block design with run as a random variable. Gel electrophoresis showed the pattern of proteins in -e was similar to that in solubilized SBM; for +e, higher molecular weight proteins present in SBM were reduced and more lower molecular weight proteins were apparent. Glycogen amount was greater with -e (15.2 mg) than +e (13.6 mg; Effects: protease, P<0.01; supernatant dose, P=0.76; interaction, P=0.20; SED 0.68) with a tendency for a quadratic effect of SUP dose (P=0.08). Comparison of +e and tryptone at the 2 common levels of N gave glycogen values of 13.8 mg for +e and 11.6 mg for tryptone (P<0.01) with no effects of N dose (P=0.17) or the interaction (P=0.97; SED = 0.56). Lower glycogen values for +e vs. -e and for tryptone vs. +e indicate reduced storage of glycogen with +e and tryptone, describing potentially more efficient fermentations, ostensibly due to relatively greater amounts of more immediately available degradable protein and peptides. Keywords: fermentation, protein, glycogen