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United States Department of Agriculture

Agricultural Research Service

Title: Influence of Subtherapeutic Chlortetracycline and Dietary Protein on Circulating Concentration of Insulin-Like Growth Factor-1 in Growing Beef Steers

Authors
item Mcleod, Kyle - UNIVERSITY OF KENTUCKY
item Baldwin, Ransom
item Rumsey, Theron
item Elsasser, Theodore
item Kahl, Stanislaw
item Streeter, Marshall - ALPHARMA INC.

Submitted to: Journal of Animal and Veterinary Advances
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 26, 2003
Publication Date: December 8, 2003
Citation: McLeod, K.R., Baldwin, R.L., Rumsey, T.S., Elsasser, T.H., Kahl, S., Streeter, M.N. 2003. Influence of subtherapeutic chlortetracycline and dietary protein on circulating concentration of insulin-like growth factor-1 in growing beef steers. Journal of Animal and Veterinary Advances. 2:531-35.

Interpretive Summary: The objective of this study was to determine the effects of chlortetracycline (CTC), an antibiotic, on plasma concentrations of insulin-like growth factor-1 (IGF-1) in bovine receiving two levels of dietary protein. Thirty-two beef steers were used to assesses treatments consisting of diets containing either marginal (10%) or adequate (13%) amounts of crude protein supplemented with a corn meal carrier (500 g/d) containing either 0 or 350 mg CTC. Blood samples were collected from each steer via jugular puncture on d 0, 7, 14, 28, 56, and 84 and plasma concentrations of IGF-1 were determined. Across the 84-d sampling period, mean plasma IGF-1 concentration was greater in steers fed 13% protein compared with those fed 10% protein. However, there was a tendency for a CTC × dietary protein interaction. On days 7 and 14 plasma IGF-1 concentration in steers fed 10% protein was greater for those receiving CTC compared with those fed carrier alone. However, by d 28 only a numerical difference was observed and by d 56 this temporal effect of CTC was no longer apparent. Results from this study suggest that oral administration of a subtherapeutic amount of CTC increases circulating IGF-1 concentrations in a temporal fashion in steers when dietary protein supply is marginal.

Technical Abstract: The objective of this study was to determine the effects of oral administration of a subtherapeutic amount of chlortetracycline (CTC) on plasma concentrations of insulin-like growth factor-1 (IGF-1) in bovine receiving two levels of dietary protein. Thirty-two beef steers, weighing 286 ± 3 kg, were allotted randomly by weight to a factorial arrangement of treatments consisting of diets containing either marginal (10%) or adequate (13%) amounts of crude protein supplemented with a corn meal carrier (500 g/d) containing either 0 or 350 mg CTC. Blood samples were collected from each steer via jugular puncture on d 0, 7, 14, 28, 56, and 84 and plasma concentrations of IGF-1 were determined by radioimmunoassay. Across the 84-d sampling period, mean plasma IGF-1 concentration was greater (P < .03) in steers fed 13% protein compared with those fed 10% protein. However, there was a tendency (P < .11) for a CTC × dietary protein interaction. Analysis within d revealed that on d 7 and 14 plasma IGF-1 concentration in steers fed 10% protein was greater for those receiving CTC compared with those fed carrier alone (CTC × dietary protein, P < .10). However, by d 28 only a numerical difference was observed and by d 56 this temporal effect of CTC was no longer apparent. Results from this study suggest that oral administration of a subtherapeutic amount of CTC increases circulating IGF-1 concentrations in a temporal fashion in steers when dietary protein supply is marginal.

Last Modified: 7/9/2014
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