Effects of dietary forage and calf starter on ruminal pH and transcriptomic adaptation of the rumen epithelium in Holstein calves during the weaning transition.
We investigated the relationship between ruminal pH and transcriptomic adaptation of the rumen epithelium (RE) of calves fed calf starter with and without forage during the weaning transition. Holstein calves were assigned to groups fed calf starter either with forage (HAY group, n = 3) or without forage (CON group, n = 4). Ruminal pH was measured continuously, and rumen fluid and epithelium were collected 3 wk after weaning. mRNA expression profiles of the RE were examined by one-color microarray. Differentially expressed genes (DEGs) were investigated using the Ingenuity Pathway Analysis (IPA). Mean and maximum ruminal pH were significantly (P < 0.05) higher, and the duration of pH < 5.8 during 1 day was significantly (P < 0.05) shorter, in the HAY group. The proportion of ruminal acetate and the acetate-to-propionate ratio were significantly (P < 0.05) lower in the CON group. DEGs encoding transcription regulators (SREBP1), insulin-like growth factor binding proteins (IGFBP7 and CTGF), ketogenic enzymes (HMGCL, BDH1, and BDH2), and a transporter (SLC16A3) were identified (P < 0.05) between the two groups. A growth factor (TGFB1) and signaling pathway (EGF and EGFR) were activated as upstream regulators. These results suggest that dietary forage alleviates ruminal acidosis, and the decrease in ruminal pH may damage the RE, leading to changes in gene expression to repair the damage. Furthermore, rumen development may be regulated by growth factor (TGFB1) and signaling pathways (EGF and IGFBP) for adaptation to feeding on calf starter with and without forage during the weaning transition.
United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
Yo-Han
YH
Kim
United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
Noriyuki
N
Toji
United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.|Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan; and.
Keiichiro
K
Kizaki
National Institute of Livestock and Grassland Science, Tsukuba, Ibaraki, Japan.
Shiro
S
Kushibiki
Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan; and.
Toshihiro
T
Ichijo
United Graduate School of Veterinary Science, Gifu University, Gifu, Japan; sshigeru@iwate-u.ac.jp.|Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan; and.
Shigeru
S
Sato
D000222:Adaptation, Physiological / Q000235:genetics*; D000821:Animal Feed; D000818:Animals; D002417:Cattle; D002784:Cholesterol / Q000096:biosynthesis; D004032:Diet; D004848:Epithelium / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005786:Gene Expression Regulation; D006863:Hydrogen-Ion Concentration; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D012417:Rumen / Q000378:metabolism*; D059467:Transcriptome / Q000235:genetics*; D014886:Weaning
D005232:Fatty Acids, Volatile; D012333:RNA, Messenger; D002784:Cholesterol
calf weaning; forage; microarray; rumen epithelium; ruminal pH