The objective of this study was to evaluate the effect of 2 Saccharomyces cerevisiae fermentation products: Diamond V Original XPC (XPC) and NutriTek (NutriTek) on in vitro VFA production on forage samples from 5 countries in Europe. Eight different forage samples were collected from the 5 countries: Poland [corn silage (CS PL) and legume forage (LF PL)]; Germany [corn silage (CS DE)]; United Kingdom [hybrid rye forage (HRF GB) and perennial rye forage (PRF GB)]; Czech Republic [mixed grasses with fescue (MGF CZ)]; and Netherlands [perennial rye forage (PRF NL) and corn silage (CS NL)]. To each serum bottle, treatments were included based on the recommended feeding rate for XPC (14 g/hd/d) and NutriTek (19 g/hd/d) along with 0.3 g of forage. Each serum bottle was inoculated with 40 mL of a 5% buffered rumen fluid from cows on a diet of 70% forage and 30% concentrate and was incubated for 24 h. Four experiments were performed to generate 10 replicates per treatment and diet. Each forage was analyzed separately using the GLM model of JMP, means were compared using Tukey analysis, and significance was defined as P ≤ 0.05. Percent increases in acetate (A), propionate (P), butyrate (B), and total VFA (T) concentrations are reported in Table 1. Significant treatment effects were observed (indicated with *) in all forage samples tested after 24 h with few exceptions. In conclusion, XPC enhanced in vitro VFA production over Control and Nutritek further enhanced VFA production over XPC on all of the forage samples tested. Results suggest that XPC and NutriTek could enhance ruminal VFA production from these forages of European origin. Table 1. Percent increases of ruminal VFA production by XPC and NutriTek

Forage	XPC over Control					NutriTek over XPC
A	P	B	T	A	P	B	T
CS PL	2.9	17.7*	6.4*	8.1*		6.1*	20.7*	4.8*	11.3*
LF PL	5.8*	7.8*	7.4*	6.6*		2.0	8.6*	4.1*	3.9*
CS DE	1.9	26.8*	3.3	10.4*		9.2*	27.2*	7.5*	16.5*
HRF GB	9.5*	13.3*	7.4*	10.0*		9.0*	18.4*	6.8*	1.6*
PRF GB	11.2*	14.3*	9.1*	12.1*		6.1*	13.1*	4.4*	8.0*
MGF CZ	10.0*	13.3*	11.1*	11.2*		5.6*	14.5*	1.3	7.9*
PRF NL	7.1*	7.0*	7.7*	7.0*		2.4	9.8*	1.8	4.9*
CS NL	2.4	27.3*	9.7*	11.2*		8.4*	31.7*	5.9*	17.2*