Submitted to: Poultry Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 2, 1998
Publication Date: N/A
Technical Abstract: Indian River male broiler chickens growing from 7 to 28 d of age were fed diets containing either 120 or 300 g crude protein and 0 or 1 mg T3/kg of diet to study lipogenesis. Dietary treatment groups were sampled at 7, 14, 21, 28, 33, 35, 37 and 40 d. In vitro lipogenesis was determined by incubating liver explants for 2 h at 37 C in Hanks salts containing 25 mM HEPES and 10 mM [2-14C]acetate. Growth and feed consumption from 7 to 28 d increased (P<0.01) when dietary protein was increased from 120 to 210 g/kg diet. T3 depressed (P<0.01) growth and feed intake. A low-protein diet increased (P<0.05) and T3 decreased lipogenesis in 28-d old chickens. This effect was noted as early as 14 d. T3 increased plasma free fatty acid levels. Plasma IGF-I was greater in birds fed the higher level of crude protein during the period from 7 to 28 d. Again, this effect was noted as early as 14 d but was only sustained for 6 d following the switch to a common diet.. In contrast, T3 did not alter IGF-I levels. Following the change to a common diet, birds fed T3 from 7 to 28 d grew at greater rates from 28 to 40 d of age although final body weights were less than controls. Compensatory gain during this period was not sufficient to attenuate depressions in growth caused by early nutritional challenges. In vitro lipogenesis at 40 d of age was not affected by either crude protein or T3. Changes in metabolism elicited by either changes in dietary protein levels or hormone treatments may be specific to the particular dosing interval and are only sustained for a short period of time following the feeding of a common diet.