|Nisbet, David - Dave|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/25/2009
Publication Date: 4/20/2009
Citation: Krueger, N.A., Anderson, R.C., Callaway, T.R., Edrington, T.S., Beier, R.C., Shelver, W.L., Nisbet, D.J. 2009. Effects of antibodies and glycerol as potential inhibitors of ruminal lipase activity [abstract]. In: Proceedings of the 2009 Conference on Gastrointestinal Function, April 20-22, Chicago, IL. p. 575. Interpretive Summary:
Technical Abstract: Ruminant-derived foods contain high proportions of saturated fats, a result of ruminal biohydrogenation, which rapidly saturates and thus limits the availability of free unsaturated fatty acids for assimilation. Strategies to enrich ruminant-derived foods with unsaturated fatty acids are desired as these are considered beneficial for good human health. Lipolysis is a pre-requisite for biohydrogenation because saturase enzymes act only on free fatty acids. This study aimed to evaluate the effects of bacteria-specific IgY antibodies and glycerol on rates of free fatty acid (FFA) accumulation during in vitro incubation of mixed rumen microbes. The positive ruminal bacteria Anaerovibrio lipolytica 5S, Butyrivibrio fibrisolvens strain H17C, Clostridium chauvoei, and Propionibacterium acnes were harvested and used for preparation of IgY antibodies. The developed antibodies were tested against the lipolytic activity expressed by mixed populations of rumen bacteria obtained from a cannulated cow receiving a 50% grain, 50% dried distillers grains diet. Additionally, two levels of glycerol were tested for their potential inhibitory effect against ruminal lipolysis by mixed rumen microbes. Antibodies raised against the whole cell preparations reduced (P < 0.05) the rate of FFA accumulation as compared to controls (normalized to 100%), with antibodies raised against P. acnes and C. chauvoei being less effective in reducing the rate of FFA accumulation (73.7% and 73.6% that of controls, respectively) than those raised against A. lipolytica 5S and B. fibrisolvens H17C (50.3% and 51.2% of controls, respectively). Results from in vitro incubations of ruminal contents with glycerol support, but do not yet prove, our hypothesis that glycerol may exhibit endproduct inhibition of lipolysis as evidenced by 48% and 77% reductions (P < 0.05) in rates of FFA accumulation in incubations supplemented with 2% or 20% added glycerol, respectively, as compared to controls (5.06 +/- 0.06 µmol FFA/mL per h). These results provide evidence that inhibiting bacterial fat degradation may promote ruminal passage of total lipid, thereby providing greater proportions of beneficial unsaturated fat for incorporation into beef products.