title: Effects of different ratios and storage periods of liquid brewer's yeast mixed with cassava pulp on chemical composition, fermentation quality andin vitroruminal fermentation.
abstract: OBJECTIVE
  This study aims to evaluate the chemical composition, fermentation quality andin vitroruminal fermentation of various ratios and storage periods of liquid brewer's yeast (LBY) mixed with cassava pulp (CVP).
  
  
  METHODS
  Four mixtures of fresh LBY and CVP were made (LBY0, LBY10, LBY20, and LBY30 for LBY:CVP at 0:100, 10:90, 20:80, and 30:70, respectively) on a fresh matter basis, in 500 g in plastic bags and stored at 30 to 32°C. After storage, the bags were opened weekly from weeks 0 to 4. Fermentation quality andin vitrogas production (IVGP) were determined, as well as the dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber, acid detergent fiber and acid detergent lignin contents.
  
  
  RESULTS
  The contents of CP and EE increased, whereas all other components decreased, in proportion to LBY inclusion (p<0.01). The DM and OM contents gradually decreased in weeks 3 and 4 (p<0.05), while EE contents were lowest in week 0. The pH, ammonia nitrogen per total nitrogen (NH3-N/TN) and V-score in each mixture and storage period demonstrated superior fermentation quality (pH≤4.2, NH3-N/TN≤12.5%, and V-score>90%). The pH increased and NH3-N/TN decreased, with proportionate increases of LBY, whereas the pH decreased and NH3-N/TN increased, as the storage periods were extended (p<0.01). Although IVGP decreased in proportion to the amount of LBY inclusion (p<0.01),in vitroorganic matter digestibility (IVOMD) was unaffected by the mixture ratios. The highest IVGP and IVOMD were observed in week 0 (p<0.01).
  
  
  CONCLUSIONS
  The inclusion of LBY (as high as 30%) into CVP improves the chemical composition of the mixture, thereby increasing the CP content, while decreasing IVGP, without decreasing fermentation quality and IVOMD. In addition, a preservation period of up to four weeks can guarantee superior fermentation quality in all types of mixtures. Therefore, we recommend limiting the use of CVP as a feed ingredient, given its low nutritional value and improving feed quality with the inclusion of LBY.
authors.affiliation: Khon Kaen Animal Nutrition Research and Development Center, Khon Kaen 40260, Thailand.
authors.forename: Sukanya
authors.initials: S
authors.lastname: Kamphayae
authors.affiliation: Laboratory of Animal Husbandry Resources, Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kumagai
authors.affiliation: Khon Kaen Animal Nutrition Research and Development Center, Khon Kaen 40260, Thailand.
authors.forename: Wanna
authors.initials: W
authors.lastname: Angthong
authors.affiliation: Khon Kaen Animal Nutrition Research and Development Center, Khon Kaen 40260, Thailand.
authors.forename: Ramphrai
authors.initials: R
authors.lastname: Narmseelee
authors.affiliation: Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Nakhon Ratchasima 30000, Thailand.
authors.forename: Smerjai
authors.initials: S
authors.lastname: Bureenok
keywords: Cassava Pulp; Chemical Composition; Fermentation Quality; In vitro Ruminal Fermentation; Liquid Brewer’s Yeast