|Spicer, L. - OKLAHOMA STATE UNIV.|
|Lucy, M. - UNIV. OF MISSOURI|
|Olson, T. - UNIV. OF FLORIDA|
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2004
Publication Date: June 10, 2004
Citation: Chase, C.C., Riley, D.G., Elsasser, T.H., Spicer, L.J., Lucy, M.C., Coleman, S.W., Olson, T.A. 2004. Effect of insulin and growth hormone administration to mature miniature brahman cattle on circulating concentrations of metabolic hormones and metabolites. Journal of Animal Science: Vol.82, Suppl.1/ Journal of Dairy Science: Vol.87, Suppl.1/ Poult. Sci. Vol. 83, Suppl.1. Technical Abstract: The objective of this study was to determine the effect of administration of GH, insulin (INS), and GH plus INS to mature miniature Brahman cows (n = 6; 9.7 ' 2.06 yr; 391 ' 48.6 kg) and bulls (n = 8; 9.4 ' 2.00 yr; 441 ' 54.0 kg) on plasma concentrations of metabolic hormones (GH, INS, IGF-I) and metabolites (glucose, urea nitrogen [PUN]). We hypothesized that IGF-I secretion could be enhanced by concomitant administration of exogenous GH and INS, but not by either hormone alone. Animals were allotted to a modified crossover design that included four treatments: control (CON), GH, insulin (INS), and GH+INS. At the start of the study, one-half of the animals were administered GH (POSILAC; 14-d slow release) and the other one-half served as controls (CON) for 7 d. Beginning on day 8 and for 7 d, insulin (Novolin L) was administered (0.125 IU/kg BW) twice daily (0700 and 1900) to all animals; hence the INS and GH+INS treatments. Animals were rested for 14 d and then were switched to the other treatment combination. Blood samples were collected at 12-h intervals during the study. Data were analyzed using PROC MIXED and fixed effects included age, sex, treatment, period, and interactions. Animal within treatment-period combinations was a random effect. Sex affected (P < 0.05) plasma concentrations of metabolic hormones but not (P > 0.15) blood metabolites. Compared to CON, GH treatment increased (P < 0.01) mean plasma concentrations of GH (11.1 vs 15.7 ' 0.94 ng/mL), INS (0.48 vs 1.00 ' 0.081 ng/mL), IGF-I (191.3 vs 319.3 ' 29.59 ng/mL), and glucose (73.9 vs 83.4 ' 2.12 mg/dL), but decreased (P < 0.05) PUN (14.2 vs 11.5 ' 0.75 mg/dL). Compared to INS, GH+INS treatment increased (P < 0.05) mean plasma concentrations of INS (0.71 vs 0.96 ' 0.081 ng/mL), IGF-I (228.7 vs 392.3 ' 29.74 ng/mL) and glucose (48.1 vs 66.70 ' 2.12 mg/dL), decreased (P < 0.01) PUN (13.6 vs 10.4 ' 0.76 mg/dL), and did not affect GH (13.5 vs 12.7 ' 0.95 ng/mL). In the miniature Brahman model, using mature animals, both GH and GH+INS treatments dramatically increased circulating concentrations of IGF-I.