Further studies on carry-over effects of dietary crude protein and triiodothyronine (T3) in broiler chickens.
Indian River male broiler chickens growing from 7 to 28 d of age were fed on diets containing either 120 or 210 g crude protein and 0 or 1 mg triiodothyronine (T3)/kg diet to study in vitro lipogenesis (IVL). In addition, a carry-over period (180 g crude protein/kg diet from 28 to 40 d of age) was used to test the persistence of prior treatment effects. The higher protein level increased, but T3 decreased (P < 0.01) growth and feed consumption at 28 d of age. The lower protein level increased (P < 0.05) and T3 decreased IVL in 28-d-old chickens. These effects were only sustained for 6 d following the switch to a common diet at 28 d. IVL at 40 d of age was not affected by either crude protein or T3 fed during the 7-28 d period. The higher protein level increased plasma insulin-like growth factor-1 during the period from 7 to 28 d; however, this effect lasted for only 6 d following the switch to a common diet. Plasma growth hormone (GH) at 28 d of age was inversely related to dietary protein level. Changing to a common level of crude protein did not change plasma GH values at 12 d, indicating that the nutritional state of the young chicken may affect GH at a later period of life. Metabolic changes noted in this study were rapid and maintained for a short period of time following the feeding of a common diet.
Rosebrough
R W
RW
Growth Biology Laboratory, United States Department of Agriculture-Agricultural Research Service, Beltsville Agricultural Research Center, MD 20705, USA. Rosebro@GGPL.ARSUSDA.GOV
McMurtry
J P
JP
Vasilatos-Younken
R
R
D000704:Analysis of Variance; D000818:Animals; D002645:Chickens / Q000254:growth & development* / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004435:Eating / Q000187:drug effects; D006128:Growth / Q000187:drug effects; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis; D008099:Liver / Q000378:metabolism; D008297:Male; D013997:Time Factors; D014284:Triiodothyronine / Q000008:administration & dosage* / Q000378:metabolism
D004044:Dietary Proteins; D008055:Lipids; D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone