title: Effects of DL-malate on in vitro forage fiber digestion by mixed ruminal microorganisms.
abstract: The objective of this study was to evaluate the effects of 0, 4, 8, and 12 mM DL-malate on the in vitro mixed ruminal microorganism fermentation of alfalfa hay and Coastal bermudagrass hay. When alfalfa hay was the substrate, 4 and 8 mM DL-malate numerically increased propionate concentration, and 12 mM DL-malate increased (P < 0.10) propionate. All three concentrations of DL-malate decreased (P < 0.05) the acetate:propionate ratio. In Coastal bermudagrass hay fermentations, all three DL-malate concentrations increased (P < 0.05) propionate and decreased (P < 0.05) the acetate:propionate ratio, while 4 and 12 mM DL-malate numerically increased in vitro dry matter disappearance. When mixed ruminal microorganisms were incubated with 6.25 mM DL-lactic acid and alfalfa hay, 8 and 12 mM DL-malate increased (P < 0.05) final pH, and 12 mM DL-malate increased (P < 0.10) propionate and decreased (P < 0.10) the acetate:propionate ratio. DL-Malate treatment had little effect on in vitro dry matter disappearance. Addition of 8 and 12 mM DL-malate to Coastal bermudagrass hay plus DL-lactic acid fermentations increased (P < 0.05) final pH, and 8 mM DL-malate increased (P < 0.10) in vitro dry matter disappearance. Even though DL-malate treatment consistently increased final pH values in fermentations that included DL-lactic acid, there was not a corresponding increase in in vitro dry matter disappearance of either alfalfa hay or Coastal bermudagrass hay in the 48-h batch culture incubations.
authors.affiliation: Department of Animal and Dairy Science, 312 Rhodes Center for Animal and Dairy Science, The University of Georgia, Athens, GA 30602-2771, USA. scottm@uga.edu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Martin
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000382:microbiology; D031744:Cynodon / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D019344:Lactic Acid / Q000378:metabolism / Q000494:pharmacology; D008293:Malates / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D000455:Medicago sativa / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D012417:Rumen / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D020357:Selenomonas / Q000187:drug effects / Q000378:metabolism*
chemical_list: D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D008293:Malates; D019344:Lactic Acid; D006859:Hydrogen; C030298:malic acid; D008697:Methane