Abstract #W257

# W257
Hepatic mRNA expression of genes related to somatotropic axis and metabolism of dairy cows treated with recombinant bovine somatotropin during the periparturient period.
Paula R. B. Silva*1, Wanda Weber1, Brian Crooker1, Ricardo C. Chebel1,2, 1University of Minnesota, St Paul, MN, 2University of Florida, Gainesville, FL.

Objectives were to determine the effects recombinant bovine somatotropin (rbST) treatment during the peripartum period on hepatic mRNA expression of genes related to inflammation and immune response. Holstein cows were assigned randomly to receive no treatment (control; n = 10), 87.5 mg (rbST87.5; n = 12), or 125 mg (rbST125; n = 10) of rbST every 7 d from −21 to 21 d relative to calving. Liver biopsies were collected −21, −7, and 7 d relative to calving. Twenty 4 genes were assessed by direct molecular counts using NanoString technology. Continuous data were analyzed by ANOVA. Gene expression on d −21 was used as a covariate for analyses of mRNA expression on d −7. No differences in mRNA expression were observed among treatments on d −21 for all the genes except SOCS3, which had lower (P ≤ 0.05) mRNA expression in control cows compared with rbST87.5 cows. On d −7, expression of mRNA for ANGPTL4 and SCARB1 was higher (P ≤ 0.05) in rbST87.5 and rbST125 cows than control. Cows in the rbST87.5 treatment had (P ≤ 0.05) higher mRNA expression for HP, ICAM1, SOCS2 and XBP1 on d −7 than control cows. Control cows had (P ≤ 0.05) higher mRNA expression for HIF1A than rbST125 cows on d −7. On d 7, control cows had (P ≤ 0.05) higher mRNA expression for CXCL1, IL1RN, MYD88, NFKBIA, and SOCS3 compared with rbST87.5 and rbST125 cows. Control cows had (P ≤ 0.05) higher mRNA expression for ICAM1 and XBP1 than rbST125 cows and had higher mRNA expression for HIF1A than rbST87.5 cows. On the other hand, expression of mRNA for NR3C1 and SOCS2 was (P ≤ 0.05) lower in control cows than rbST125 and rbST87.5 cows, respectively. Treatment did not affect hepatic expression of the genes CEBPD, JUN, M-CSF1, NFKB1, PPARGC1A, STAT5B, TLR2, TNF, TNFRSF1 and TNFRSF5. The gene G-CSF was not detected. Weekly treatment of periparturient cows with rbST regulates liver mRNA expression of genes related to inflammation and immune response during the prepartum and postpartum periods. Increased postpartum mRNA expression of inflammatory and immune responses genes in control cows might be a consequence of increased incidence of postpartum diseases.

Key Words: periparturient cow, recombinant bovine somatotropin, hepatic gene expression