S. Akbari - Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Islamic Republic of Iran.
S. Ansari Mahyari - Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Islamic Republic of Iran.
A. H. Mahdavi - Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Islamic Republic of Iran.
A. Zahmatkesh - Department of Genomics and Genetic Engineering, Razi Vaccine and Serum Research Institute (RVSRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj ۳۱۹۷۶-۱۹۷۵۱, Islamic Republic of Iran.
E. Dehnavi - Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Islamic Republic of Iran.

This study was designed to investigate the effects of physical forms and hay contents of diets on gene expression of insulin-like growth factor (IGF) I and II in rumen epithelium of Holstein calves. Twelve male calves were assigned to ۴ treatments: ground (GR), texturized (TX), pellet (PL), and ground+۱۰% forage (GF). Calves were weaned on day ۵۰ of age and then slaughtered on day ۷۰ after birth. Rumen epithelial tissue samples were immediately collected for quantification of mRNA abundance. Results indicated that only IGF I expression was influenced by the dietary treatments. A significant (p<۰.۰۵) correlation between IGF I expression and each of histological parameters denoted as length of rumen villi and diameter of keratinocyte layer was observed. No significant correlation between IGF II expression and rumen histological parameters was found (p>۰.۰۵). Regarding the results, higher IGF I expression in PL and TX treatments despite the low growth rate might be due to the challenging condition of developing rumen in calves. In fact, the rumen tissue attempted to maintain rumen pH at least by induction of a higher IGF I expression.

IGF I, IGF II, Keratinocyte layer, Rumen villi, Holstein calves., لایه کراتینوسایت, پرز, گوساله های هلشتاین