title: Effects of dietary neutral detergent fiber and starch ratio on rumen epithelial cell morphological structure and gene expression in dairy cows.
abstract: This study was designed to investigate the effect of dietary neutral detergent fiber to starch ratio on rumen epithelial morphological structure and gene expression. Eight primiparous dairy cows including 4 ruminally fistulated cows were assigned to 4 total mixed rations with neutral detergent fiber to starch ratios of 0.86, 1.18, 1.63, and 2.34 in a replicated 4 × 4 Latin square design. The duration of each period was 21 d including 14 d for adaptation and 7 d for sampling. Rumen epithelial papillae were collected from the ruminally fistulated cows for morphological structure examination and mRNA expression analysis using quantitative real-time PCR of several genes related to volatile fatty acid absorption and metabolism, and cellular growth. Increasing dietary neutral detergent fiber to starch ratio resulted in a linear increase in the thickness of the stratum spinosum and basale. In contrast, expression of HMGCS2 (encoding the rate-limiting enzyme in the synthesis of ketone bodies) decreased linearly, whereas the expression of MCT2 (encoding a transporter of volatile fatty acid) increased linearly with increasing dietary neutral detergent fiber to starch ratio. As dietary neutral detergent fiber to starch ratio increased, expression of IGFBP5 (a gene related to the growth of rumen epithelial papillae) decreased, whereas IGFBP6 expression increased. Both of these IGFBP genes are regulated by short-chain fatty acids. Overall, the data indicate that dietary neutral detergent fiber to starch ratio can alter the thickness of the rumen epithelial papillae partly through changes in expression of genes associated with regulating volatile fatty acid absorption, metabolism, and cell growth.
authors.affiliation: State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; Chinese Academy of Agricultural Sciences-World Agroforestry Centre (CAAS-ICRAF) Joint Laboratory on Agroforestry and Sustainable Animal Husbandry, World Agroforestry Centre, East and Central Asia, Beijing 100193, China.
authors.forename: L
authors.initials: L
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; Chinese Academy of Agricultural Sciences-World Agroforestry Centre (CAAS-ICRAF) Joint Laboratory on Agroforestry and Sustainable Animal Husbandry, World Agroforestry Centre, East and Central Asia, Beijing 100193, China.
authors.forename: M
authors.initials: M
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; Chinese Academy of Agricultural Sciences-World Agroforestry Centre (CAAS-ICRAF) Joint Laboratory on Agroforestry and Sustainable Animal Husbandry, World Agroforestry Centre, East and Central Asia, Beijing 100193, China.
authors.forename: L S
authors.initials: LS
authors.lastname: Zhao
authors.affiliation: Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
authors.forename: J C
authors.initials: JC
authors.lastname: Xu
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
authors.forename: J J
authors.initials: JJ
authors.lastname: Loor
authors.affiliation: State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; Chinese Academy of Agricultural Sciences-World Agroforestry Centre (CAAS-ICRAF) Joint Laboratory on Agroforestry and Sustainable Animal Husbandry, World Agroforestry Centre, East and Central Asia, Beijing 100193, China; Hunan Co-Innovation Center of Animal Production Safety (CICAPS), Changsha 410128, China. Electronic address: budengpan@126.com.
authors.forename: D P
authors.initials: DP
authors.lastname: Bu
mesh_terms: D000818:Animals; D002417:Cattle; D003902:Detergents; D004032:Diet / Q000662:veterinary; D004043:Dietary Fiber / Q000378:metabolism; D004063:Digestion; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D005285:Fermentation; D007774:Lactation; D008892:Milk / Q000737:chemistry; D012417:Rumen / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*
chemical_list: D003902:Detergents; D004043:Dietary Fiber; D013213:Starch
keywords: dairy cow; gene expression; neutral detergent fiber to starch ratio; rumen morphological