Interactions of unsaturated fat or coconut oil with Rumensin® on milk fat production might be mediated through inhibition of specific protozoal genera
Advisor:Firkins, Jeffrey L.
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Series/Report no.:2007 Edward F. Hayes Graduate Research Forum. 21st
Polyunsaturated fatty acids (PUFA) feeding often decreases protozoal numbers in the rumen. Animal-vegetable fat (AV), a by-product of the food industry, is readily available to provide PUFA in dairy diets. However, the response to AV supplementation on protozoal numbers is not consistent, possibly due to biohydrogenation (BH) of PUFA in the rumen. Long chain saturated FA are less toxic to protozoa; therefore, the BH of PUFA removes their potential inhibitory effects. In contrast, evidence from OSU supports the contention that protozoa are a vehicle for passage of PUFA or other intermediates of BH that do not promote MFD. AV supplementation in combination with Rumensin® (R), an ionophore improving feed efficiency, occasionally spontaneously decreases milk fat yield and percentage. This milk fat depression (MFD) is likely due to the partial BH of PUFA, which favors FA intermediates that are inhibitory to milk fat synthesis. Feeding coconut oil (CO) rich in medium chain fatty acids (MCFA), and therefore low in PUFA, has decreased the abundance of ruminal protozoa in sheep. We hypothesized that, while lowering protozoal populations, diets supplemented with CO in combination with R would not cause MFD as would AV diets combined with R. PUFA or MCFA in combination with R could shift ruminal fermentation and potentially depress fiber degradation, reducing fed intake.
Poster: 2nd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)