title: Short communication: grain-induced subacute ruminal acidosis is associated with the differential expression of insulin-like growth factor-binding proteins in rumen papillae of lactating dairy cattle.
abstract: The objective of this study was to characterize the mRNA expression of genes involved in the insulin-like growth factor (IGF) axis in the rumen epithelium during grain-induced ruminal acidosis. Eight lactating dairy cattle were randomly assigned to a control (38% concentrate) or a high-grain (HG; 57% concentrate) diet in a randomized study. Dry matter intake, milk production, ruminal pH, and rumen papillae gene expression were measured before treatment allocation (d 0) and on the fourth day of treatment. On d 4, no differences were observed in total feed intake and milk production; however, the cattle fed the HG diet displayed lower ruminal pH (587 ± 130 min/d below 5.6; mean ± SE) compared with cattle receiving the control diet (169 ± 145 min/d below 5.6). No change in the relative mRNA expression of IGF-1, IGF-1 receptor (IGF-1R), and IGF-binding protein 6 (IGFBP6) was detected between treatments. However, the relative expression value of IGF-binding protein 3 (IGFBP3) decreased (0.73 ± 0.07 fold, mean ± SE), whereas IGF-binding protein 5 (IGFBP5) expression increased (1.53 ± 0.20 fold). These results indicate that the IGF axis may play a role in rumen epithelial adaptation to HG diets.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
authors.forename: M A
authors.initials: MA
authors.lastname: Steele
authors.forename: O
authors.initials: O
authors.lastname: Alzahal
authors.forename: M E
authors.initials: ME
authors.lastname: Walpole
authors.forename: B W
authors.initials: BW
authors.lastname: McBride
mesh_terms: D000138:Acidosis / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D000821:Animal Feed; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism* / Q000503:physiopathology; D002523:Edible Grain; D005260:Female; D006863:Hydrogen-Ion Concentration; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism / Q000502:physiology*; D007774:Lactation / Q000378:metabolism / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012417:Rumen / Q000378:metabolism* / Q000502:physiology
chemical_list: D018969:Insulin-Like Growth Factor Binding Proteins