Glycerol inhibition of ruminal lipolysis in vitro.
Supplemental glycerol inhibits rumen lipolysis, a prerequisite for rumen biohydrogenation, which is responsible for the saturation of dietary fatty acids consumed by ruminant animals. Feeding excess glycerol, however, adversely affects dry matter digestibility. To more clearly define the effect of supplemental glycerol on rumen lipolysis, mixed populations of ruminal bacteria were incubated with 6 or 20% glycerol (vol/vol). After 48-h anaerobic incubation of mixed culture rumen fluid, rates of free fatty acid production (nmol/mL per h) for the 6 and 20% glycerol-supplemented samples were decreased by 80 and 86%, respectively, compared with rates from nonsupplemented control cultures (12.4±1.0; mean ± SE). Conversely, assay of the prominent ruminal lipase-producing bacteria Anaerovibrio lipolyticus 5S, Butyrivibrio fibrisolvens 49, and Propionibacterium species avidum and acnes revealed no effect of 2 or 10% (vol/vol) added glycerol on lipolytic activity by these organisms. Supplementing glycerol at 6% on a vol/vol basis, equivalent to supplementing glycerol at approximately 8 to 15% of diet dry matter, effectively reduced lipolysis. However, the mechanism of glycerol inhibition of ruminal lipolysis remains to be demonstrated.
Department of Animal Science, Texas A&M University, College Station 77843.
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Edwards
United States Department of Agriculture/Agricultural Research Service, Southern Plains Agricultural Research Center, Food & Feed Safety Research Unit, 2881 F&B Road, College Station, TX 77845. Electronic address: Robin.Anderson@ars.usda.gov.
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Anderson
Department of Animal Science, Texas A&M University, College Station 77843.
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Miller
Department of Animal Science, Texas A&M University, College Station 77843.
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Taylor
Department of Animal Science, Texas A&M University, College Station 77843.
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Hardin
Department of Animal Science, Texas A&M University, College Station 77843.
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Smith
United States Department of Agriculture/Agricultural Research Service, Southern Plains Agricultural Research Center, Food & Feed Safety Research Unit, 2881 F&B Road, College Station, TX 77845.
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Krueger
United States Department of Agriculture/Agricultural Research Service, Southern Plains Agricultural Research Center, Food & Feed Safety Research Unit, 2881 F&B Road, College Station, TX 77845.
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Nisbet
D000818:Animals; D001826:Body Fluids / Q000378:metabolism; D045856:Butyrivibrio / Q000378:metabolism; D002417:Cattle; D005990:Glycerol / Q000494:pharmacology*; D066298:In Vitro Techniques; D008066:Lipolysis / Q000187:drug effects*; D011424:Propionibacterium / Q000378:metabolism; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology
D005990:Glycerol