The objectives were to determine the effects of Saccharomyces cerevisiae fermentation products (SCFP) on free lipopolysaccharide (LPS) in rumen fluid and feces, and on acute phase protein in blood plasma during normal feeding and SARA challenges in lactating dairy cows. Thirty-two Holstein lactating dairy cows fixed with rumen cannulas were assigned to 4 treatments, including control and 3 SCFP treatments: Diamond V Original XPC (XPC, 14 g/d)), NutriTek low concentration (NTL), and NutriTek high concentration (38 g/d, NTH) in a randomized complete block design. Treatments were administered between 4 wk before until 11 wk after calving. During lactation, cows received a total mixed ration containing 50% concentrate, with the exception that during wk 5 and 7 grain-based SARA challenges were conducted by feeding a high concentration diet (70% concentrate, DM basis). The SARA challenges increased the concentrations of LPS in rumen fluid and feces, and the concentrations of serum amyloid A (SAA), haptoglobin (HP) and LPS binding protein (LBP) in blood plasma (Table 1). The SCFP did not affect the concentrations of LPS, HP and LBP. The intercation of SCFP and SARA challange was signifiant (P < 0.05), as the SARA challenges, NTL and NTH reduced (P < 0.01) the increase in SAA. This shows that these SCFP attenuated the inflammatory effect of the SARA challange. Table 1.

Item	SARA				P-value
	Week 4	Week 5	Week 6	Week 7
Rumen LPS (EU/mL)	4,864b	60,255a	5,998b	64,863a	<0.01
Fecal LPS(EU/mL)	9,616b	61,235a	7,603b	63,679a	<0.01
SAA (ug/mL)
Control	26.36c	90.36a	35.40bc	73.28ab	<0.01
XPC	21.33b	89.95a	16.41b	64.12a	<0.01
NTL	31.98ab	58.08a	19.82b	42.07ab	<0.01
NTH	9.44c	50.35ab	18.92bc	24.04bc	<0.01
HP (ug/mL)	71.8bc	171.8a	64.9c	123.0ab	<0.01
LBP (ug/mL)	11.1ab	13.6a	9.4b	10.4b	<0.01

^abcMeans in the same row with different superscripts differ (P<0.05).