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Dietary protein effects on the broiler's adaptation to triiodothyronine
R W Rosebrough1, J P McMurtry, R Vasilatos-Younken
1Livestock and Poultry Science Institute, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, MD 20705, USA. Rosebro@NS.LPSI.BARC.USDA.GOV
Growth, Development, and Aging : GDA
|August 2, 2000
Summary
Dietary protein levels influence metabolic adaptations in broiler chickens treated with triiodothyronine (T3). High protein diets altered thyroid hormone levels, but adaptive responses to T3 were similar across protein levels.
Area of Science:
- Animal Science
- Endocrinology
- Nutritional Biochemistry
Background:
- Thyroid hormones play a crucial role in avian metabolism and growth.
- The impact of dietary protein on thyroid hormone action and metabolic adaptation requires further elucidation.
- Triiodothyronine (T3) is a key thyroid hormone influencing metabolic rate and lipogenesis.
Purpose of the Study:
- To investigate the effects of varying dietary protein levels on metabolic adaptations in broiler chickens exposed to triiodothyronine (T3).
- To understand the interplay between dietary protein, thyroid metabolism, and key metabolic indicators in poultry.
- To assess the influence of T3 administration on in vitro lipogenesis, growth, feed consumption, hepatic enzymes, and plasma metabolites.
Main Methods:
- Male broiler chickens were fed diets with 120 or 300 g crude protein/kg from 7 to 28 days of age.
- At 28 days, one-half of each group received their respective diet supplemented with 1 mg/kg T3.
- Measurements including in vitro lipogenesis (IVL), growth, feed intake, hepatic enzymes, and plasma thyroid hormones/metabolites were taken at multiple time points post-T3 treatment.
Main Results:
- Lower protein diets resulted in higher in vitro lipogenesis (IVL) at 28 days.
- T3 administration significantly decreased IVL by 50% within 5 days, irrespective of dietary protein level.
- Higher protein diets were associated with increased plasma IGF-I and T4, but decreased T3 and GH.
- T3 treatment led to increased plasma T3 and decreased T4 within 3 days.
Conclusions:
- Metabolic adaptations to T3 in broiler chickens occur rapidly, primarily within 2-5 days.
- Dietary protein levels may not significantly alter the adaptive metabolic responses to exogenous T3.
- Understanding these interactions is vital for optimizing poultry nutrition and metabolic health.