|Winkelman, L. - OHIO STATE UNIVERSITY|
|Reynolds, C. - OHIO STATE UNIVERSITY|
Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2006
Publication Date: July 21, 2006
Citation: Winkelman, L.A., Elsasser, T.H., Reynolds, C.K. 2006. Plasma tumor necrosis factor-alpha concentrations during the transition period of cows fed either adlibitum or restricted diets during the dry period [abstract]. 2006 ADSA Meeting. Paper No. 111. Technical Abstract: Tumor necrosis factor-alpha (TNF-') is a pro-inflammatory cytokine that upregulates mRNA expression of suppressors of cytokine signaling (SOCS) and induces nitric oxide (NO) production. Both SOCS and NO inhibit intracellular growth hormone (GH) signaling and uncouple the somatotropic axis. Expression of TNF-' mRNA in the liver increases after calving in dairy cows, when the somatotropic axis is uncoupled, but plasma concentration of TNF-' in transition dairy cows has not been reported. The objective of our study was to measure plasma concentrations of TNF-', GH, and insulin like growth factor-I (IGF-I) over the course of transition in dairy cows. Multiparous Holstein cows (n = 18) were dried off 45 d before expected calving and fed diets at either ad libitum (AL) or restricted (R) DMI until calving. The R diet was fed to meet nutrient requirements in 9.4 kg DM/d, whereas AL cows consumed 13.7 kg DM/d. Cows were fed the same diet ad libitum for 4 wk after calving. Blood samples were collected weekly with additional sample collection on days -18, -13, -9, -5, -2, +1, +4, and +7 relative to calving. Plasma concentrations of TNF-' (uM) were unaffected by diet, but were lower (P < 0.05) after calving (5.05 vs. 4.80). Plasma GH concentrations (nM) were increased (P < 0.01) by R and greater (P < 0.01) after calving for all cows (prepartum: 0.06 vs. 0.05; postpartum: 0.15 vs. 0.11, for R vs. AL, respectively). Plasma IGF-I concentrations (pM) were unaffected by treatment before calving, but decreased (P < 0.01) after calving for all cows (prepartum: 13.13 vs. 12.89; postpartum: 9.17 vs. 8.66, for R vs. AL, respectively). During wk 1 postpartum, IGF-I concentrations were lower (P < 0.01) for AL vs. R (7.65 vs. 10.12). Plasma concentrations of TNF-' may not reflect tissue concentrations and activity, and therefore may not be relevant to the regulation of the somatotropic axis in the liver of the transition dairy cow.