Evaluation of Techniques in Ruminant Nutrition for Sustainable Production

Abstract

The objective of this work was to evaluate four different techniques in ruminant production in order to increase the sustainability of the system.

The first study tested the hypothesis that yeast supplementation during heat-stress inducing environmental conditions may change energy partitioning, nitrogen metabolism, and ruminal parameters in growing ruminants. Additionally, this study used an in vitro model to simulate the lasting effects of elevated environmental conditions and yeast supplementation on the fermentation dynamics of rumen microorganisms. This study did not find any positive or negative impacts of yeast supplementation on energy partitioning and nitrogen metabolism during high climatic condition. The in vitro study showed that previous exposure to high temperatures and humidity as well as yeast supplementation could change the fermentation patterns of rumen microorganisms.

The second study examined the effects of post-incubation handling of in vitro fermentation bottles. This study found differences in pressure, volume, temperature, and methane concentration depending on post-incubation handling method. Additionally, this study concluded that the presence of water vapor may be a source of inflation when comparing in vitro measurements to in vivo measurements of methane. The study proposed a series of equations to remove water vapor from the estimated methane concentrations.

The third study compared volatile fatty acid (VFA) determination protocols using gas chromatography (GC) or high-performance liquid chromatography (HPLC). Both rumen fluid samples and chemical standards were used to determine the predictive adequacy of the two equipment methods. The HPLC method was more precise and accurate when compared to the GC method when using the chemical standards. The GC protocol consistently overpredicted concentrations of VFA in rumen fluid when compared to the results of the HPLC protocol. This study suggests expansion of this investigation to alternate machines and laboratories.

The fourth study developed a lysine-based medium to selectively enumerate Fusobacterium necrophorum from the bovine rumen and compared enumeration efficacy to a previously published selective lactate-based medium. While the modified-lysine medium did not enumerate F. necrophorum as well as the modified-lactate medium, this study provided valuable insight into the dynamics between yeast or virginiamycin supplementation and F. necrophorum. There was an increase of ruminal counts of F. necrophorum with live yeast supplementation and a dose-dependent increase when animals were supplemented with virginiamycin. Fusobacterium varium was also found in notable concentrations in rumen contents. Lastly, this study concluded that the enumerated populations of F. necrophorum are significantly less than the reported concentrations, possibly due to regional differences of sampled animals.