Table 6.

Summary of studies in periparturient dairy cows investigating the effects of supplemental live yeast or yeast-based products on rumen epithelium, liver, colon, and plasma biomarkers

Nutraceutical	Treatment	Period	Tissue/Cells	Main outcome	Reference
Live yeast	1 × 1010/d/head	From − 21 to 21 d relative to calving	Rumen	Dry cows responded rapidly to live yeast with Greater abundance of TLR4 and IL10 prepartum	[124]
			Colon	Greater abundance of DEFB1
Live yeast	2.5 g/d/head precalving and 10 g/d/head postcalving	From −14 to 70 d relative to calving	Liver	Greater glycogen	[109]
			Plasma	Greater phosphorous concentration
Saccharomices cereviseae fermentation product	19 g/d/head	From 28 to 42 d relative to calving	Rumen	Greater abundance of IGFBP6 In cows fed a high-starch diet increased abundance of BDH2	[122]
	19 g/d/head	From − 28 to 42 d relative to calving	Plasma	Lower haptoglobin at 7 d postpartum	[115]
	19 g/d/head	From −29 to 42 d relative to calving	Liver	Tendency to increase PCK1 mRNA abundance	[114]
			Liver	Decreased cholesterol
			Plasma	Increased cholesterol
	56 or 112 g/d/head	From −4 weeks to 4 weeks relative to calving	Plasma	Higher glucose between partum and + 3 d Higher urea at partum and + 1 d. With the dosage of 112 g/d/head, higher BHB at 3 d postpartum Lower cortisol	[116]

TLR4 toll-like receptor 4, IL10 interleukin 10, DEFB1 β-defensin, IGFBP6 insulin like growth factor binding protein 6, BDH2 3-hydroxybutyrate dehydrogenase 2, PCK1 phosphoenolpyruvate carboxykinase 1, BHB beta-hydroxybutyrate