A sustainable increase in livestock production would require selection for improved feed efficiency, but the mechanisms underlying this trait and explaining its large individual variation dairy ruminants remain unclear. This study was conducted lactating ewes to test hypothesis that rumen biohydrogenation (BH) differ between high- low-efficiency animals, these differences be reflected fatty aci...

Development of Methodology and Characterization of Ruminal Lipase-Producing Bacteria In Vitro. (May 2011) Holly Danielle Edwards, B.S., Iowa State University Co-Chairs of Advisory Committee: Dr. Rhonda K. Miller Dr. T. Matthew Taylor Hydrolysis of dietary lipids to free fatty acids (FFA) is a prerequisite for ruminal biohydrogenation, a bacterially mediated process that extensively saturates un...

This study evaluated the effects of tannins on ruminal biohydrogenation (BH) due to shifts in the ruminal microbial environment in sheep. Thirteen lambs (45 days of age) were assigned to two dietary treatments: seven lambs were fed a barley-based concentrate (control group) while the other six lambs received the same concentrate with supplemental quebracho tannins (9.57% of dry matter). At 122 ...

Following the isolation, cultivation and characterization of the rumen bacterium Anaerovibrio lipolyticus in the 1960s, it has been recognized as one of the major species involved in lipid hydrolysis in ruminant animals. However, there has been limited characterization of the lipases from the bacterium, despite the importance of understanding lipolysis and its impact on subsequent biohydrogenat...

High fat ingredients are commonplace in diets fed to dairy cattle and include commercial fat supplements designed for convenient transport and mixing, oilseeds such as cottonseed or soybeans, or byproducts such as distillers grains, tallow, or food processing wastes. additional fat remain focused today, as in the past, on minimizing problems with intake, rumen function, and digestibility. All o...

From a genomic analysis of rumen butyrivibrios (Butyrivibrio and Pseudobutyrivibrio sp.), we have re-evaluated the contribution of electron transport phosphorylation (ETP) to ATP formation in this group. This group is unique in that most (76%) genomes were predicted to possess genes for both Ech and Rnf transmembrane ion pumps. These pumps act in concert with the NifJ and Bcd-Etf to form a elec...

Studies on microbial biohydrogenation of fatty acids in the rumen are of importance as this process lowers the availability of nutritionally beneficial unsaturated fatty acids for incorporation into meat and milk but also might result in the accumulation of biologically active intermediates. The impact was studied of adsorption of 22:6n-3 (DHA) to particulate material on its disappearance durin...

Ruminant milk fat is of unique composition among terrestrial mammals, due to its great diversity of component fatty acids. The diversity arises from the eVects of ruminal biohydrogenation on dietary unsaturated fatty acids and the range of fatty acids synthesized de novo in the mammary gland. Forty to sixty per cent of milk fatty acids are long-chain (predominantly C18) fatty acids derived from...