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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Dairy Forage Research » Research » Publications at this Location » Publication #324064
Title: In vitro ruminal fermentation of treated alfalfa silage using ruminal inocula from high and low feed-efficient lactating cows

Author
item CONTRERAS-GOVEA, FRANCISCO - University Of Wisconsin
item Muck, Richard
item Weimer, Paul
item Hymes Fecht, Ursula

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2016
Publication Date: 7/22/2016
Citation: Contreras-Govea, F.E., Muck, R.E., Weimer, P.J., Hymes Fecht, U.C. 2016. In vitro ruminal fermentation of treated alfalfa silage using ruminal inocula from high and low feed-efficient lactating cows. Journal of Applied Microbiology. 121:333-340.

Interpretive Summary: Feed and feed components for cattle are often assessed for digestibility by incubating them in fluid from the cow’s main stomach (rumen). This measurement of digestibility (in vitro true dry matter digestibility) is useful in formulating rations that better meet cows’ dietary needs. We were interested to determine if the in vitro digestibility of a silage was affected by the cow used as the source of the rumen fluid or by the additive used in making the silage. The silage additive did not affect digestibility as expected. However, rumen fluid from cows that were more efficient at producing milk from their ration produced a higher in vitro true dry matter digestibility than rumen fluid from cows that were less efficient. This result will be of significance to scientists, dairy cattle nutritionists and forage testing professionals as they compare various feedstuffs

Technical Abstract: The objective was to assess the effect of two additives on alfalfa silage and on in vitro ruminal fermentation when using ruminal inocula prepared from high feed-efficient (HE) and low feed-efficient (LE) lactating cows. Second and third cut alfalfa was harvested at 40% bloom stage, treated with control (no additive), Lactobacillus plantarum (LP), or formic acid (Formic), ensiled in 1.0 L minisilos, and fermented for 60 d. Fermented alfalfa was incubated in vitro for 24 h using ruminal inoculum from HE and LE lactating cows. The pH was lower on alfalfa silage treated with LP and Formic and produced lower ammonia-N than did the control. In vitro true dry matter digestibility was higher with ruminal inoculum coming from HE cows than LE cows, but there was not a consistent effect of treated alfalfa on microbial biomass yield and in vitro volatile fatty acids. Overall, the in vitro true dry matter digestibility was numerically greater with ruminal inoculum from higher feed-efficient cows although statistical significance was only demonstrated with the first-cut alfalfa. However, treated alfalfa silage did not show the effect expected on in vitro microbial biomass yield. These results indicate that the feed efficiency of cows used as a source of ruminal inocula may affect in vitro true dry matter digestibility and be a source of variation across in vitro runs.