Aim: This experiment was conducted to determine the effect of yeast cell wall (YCW) supplementation on production performances and blood biochemical indices such as liver enzyme activities, energy metabolites, and electrolyte concentrations of dairy cows in different lactation periods (LP). Materials and Methods: Thirty-two lactating Holstein cows were assigned into 2×2 factorial arrangement, in which the factors were the treatment (TM) (control [n=16] vs. YCW [n=16]) and the LP (early lactation [n=14] vs. mid-lactation [n=18]). The cows with day in milk (DIM) 120 (179±5 DIM) were assumed as mid-lactating cows. The YCW (SafMannan; Phileo, Lesaffre Animal Care, France) was used as the dietary supplement (10 g/cow/day) in this experiment. The statistical analysis of the data was performed by the two-way analysis of variance using the general linear model procedure to determine the main effects (TM and LP) and their interaction (TM×LP) on production performances and blood biochemical parameters of experimental cows. Results: No significant effects (p>0.05) of YCW supplementation on production performances and blood biochemical indices of cows in TM groups (control vs. YCW) were observed; however, some obvious effects were detected in LP (early- and mid-lactation). Milk and milk component yield of cows in early lactation were significantly higher (p0.05) with the YCW supplementation. The higher level (p<0.05) of serum albumin was found in mid-lactating cows after YCW supplementation. Before the experiment, the higher (p<0.05) non-esterified fatty acid (NEFA) and NEFA/total cholesterol (T-Cho) ratio, and the lower (p<0.05) calcium (Ca) concentration were observed in early lactating cows comparison with mid-lactating cows; however, there were not different after YCW supplementation. Conclusion: The positive effects of YCW supplementation on milk and milk component yields, energy metabolite, especially NEFA and NEFA/T-Cho ratio and Ca concentration were observed in early lactating cows rather than mid-lactating cows.

The objective of this study was to evaluate effects of butyrate supplementation on plasma concentration of glucagon-like peptide-2 (GLP-2), apparent total-tract digestibility, and responses to a grain challenge of lactating dairy cows fed diets differing in starch content. Eight Holstein cows averaging 58.6 ± 9.96 d in milk (4 primiparous cows fitted with rumen cannula and 4 multiparous intact cows) were blocked by parity and assigned to one of two 4 × 4 Latin squares balanced for carryover effects with a 2 × 2 factorial arrangement of treatments. Treatments were dietary starch content [20.6 vs. 27.5%, respectively, for low starch (LS) and high starch (HS)] and butyrate supplementation (butyrate vs. control) with 21-d periods. Butyrate was provided as Gustor BP70 WS (Norel, S.A., Madrid, Spain), containing 70% sodium butyrate and 30% fatty acid mixture, at 2% of dietary dry matter (providing butyrate at 1.1% of dietary dry matter), and control premix contained 70% wheat bran and 30% fatty acid mixture. Feeds, orts, and fecal samples were collected from d 17 to 19 to determine apparent total-tract nutrient digestibility. Blood and rumen fluid samples were collected on d 19. The baseline of dry matter intake (DMI) was determined as average DMI from d 17 to 19 for each cow, and cows were feed-restricted at 60% of the baseline DMI on d 20, and a grain challenge was conducted by providing steam-flaked corn grain at 0.6% of body weight, on an as-fed basis, in addition to each treatment diet on d 21, and blood and ruminal fluid samples were collected. The interaction of dietary starch content by butyrate supplementation was significant for plasma GLP-2 concentration, being greater for cows fed butyrate with the HS diet than those fed the other 3 diets. Cows fed butyrate increased n-butyrate concentration in the ruminal fluid and tended to increase dry matter and organic matter digestibility compared with the control. During the grain challenge, rumen endotoxin concentration increased over time and was higher for cows fed the HS diets compared with those fed LS diets. However, response variables related to inflammation were not affected by the grain challenge. However, serum haptoglobin, lipopolysaccharide-binding protein, and serum amyloid-A concentrations were greater for cows fed butyrate with the LS diet, but not for those fed the HS diet. These results indicate that butyrate supplementation may increase plasma GLP-2 concentration for cows fed HS diets, and total-tract digestibility regardless of dietary starch content. However, butyrate supplementation did not mitigate inflammation in this study.

This study was designed to examine the effect of yeast cell wall (YCW) supplementation on peripheral leukocyte populations and mRNA expression of cytokines in lactating dairy cows. Fourteen Holstein lactating cows were assigned to 1 of 2 treatments; the control group (n = 7) were fed a total mixed ration without supplementation and cows in the YCW group (n = 7) were fed a total mixed ration supplemented with YCW (SafMannan; Phileo, Lesaffre Animal Care, Lille, France; 10 g/cow per day). Blood samples were collected 3 times during the experimental period [wk 0 (before any treatment), wk 4, and wk 8]. Peripheral leukocyte populations and cytokine mRNA expression of peripheral blood monocular cells were measured using flow cytometry and real-time PCR, respectively. Among the peripheral leukocyte populations, TcR1-N12(+) and CD14(+) T cells increased at wk 4, and CD4(+) T cells and CD8(+) T cells increased at wk 4 and wk 8 with YCW supplementation. The mRNA level of IL8 tended to be increased in the YCW group at wk 4. Expression of IL12A was lower in the YCW group than in the control group before the experiment (wk 0) but no differences were observed at later time points (wk 4 and wk 8). Expression of IL12A decreased in the control group and increased in the YCW group. Expression of CCR2 increased at wk 4, and CCL2 and CCL3 were increased at wk 8 in the YCW group. Thus, YCW supplementation increased the mRNA expression of cytokines in peripheral blood mononuclear cells of lactating dairy cows.