Protein and energy relationships in the broiler chicken. 12. Dietary protein and triiodothyronine (T3) effects on the response of broilers to isoproterenol and cyclic adenosine monophosphate in vitro.
Indian River male broiler chickens (7-d-old) were fed on diets containing 120, 210 or 300 g crude protein/kg + 0 or 1 mg triiodothyronine (T3)/kg diet (Expt 1) and 120, 150, 180 or 210 g crude protein/kg + 0 or 1 mg T3/kg diet (Expt 2) to determine the effects of crude protein level and T3 on growth and metabolism. Body composition of chickens was determined by a combination of dissection of muscle and abdominal fat pads, and chemical extraction (Expt 1). In vitro lipogenesis (IVL) was determined in both experiments by incubating liver explants for 2 h at 37 degrees in the presence of 10(-4) M-dibutyryl cyclic AMP (cAMP) or 10(-5) M isoproterenol (ISO) and 10(-2) M-[2-14C]acetate. Acetate incorporation into total lipid was an indication of IVL. Activity ratios for each of these additions relative to control (-cAMP-ISO) were calculated to ascertain basal v. inhibited rates of IVL. The relative muscle mass was increased by increasing crude protein from 120 to 210 g/kg diet but not from 210 to 300 g/kg diet. Dietary T3 decreased total body lipid regardless of the dietary crude-protein level. Increasing dietary crude protein decreased (P < 0.05) basal IVL (-cAMP-ISO) but not IVL (+cAMP). Dietary T3 decreased basal IVL in birds fed on the diets containing 120 and 210 g crude protein/kg but had little effect on the two inhibited states of lipogenesis (+cAMP or +ISO). The component of lipogenesis sensitive to in vitro inhibition is also the component under dietary control.
Rosebrough
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RW
Nonruminant Animal Nutrition Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville, MD 20705.
Mitchell
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AD
D000085:Acetates / Q000378:metabolism; D000818:Animals; D001823:Body Composition; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D050356:Lipid Metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D024510:Muscle Development; D011506:Proteins / Q000378:metabolism; D014284:Triiodothyronine / Q000008:administration & dosage / Q000494:pharmacology*
D000085:Acetates; D004044:Dietary Proteins; D011506:Proteins; D014284:Triiodothyronine; D000242:Cyclic AMP; D007545:Isoproterenol