title: The effect of low levels of dietary protein and calcium on growth rate, growth hormone, and vitamin D metabolism in the chick.
abstract: Two experiments were carried out on 2-week-old chicks in which they were fed protein-deficient diets for varying lengths of time with or without calcium (Ca). All deficient diets depressed the rate of growth; this depression was more marked in chicks fed the protein-deficient diet for 21/2 days than in those fed the diet for 4 days. The circulating growth hormone level was high in all protein-deficient diets but low in the diet only deficient in calcium. The low Ca-induced-rise in renal vitamin D, 1-hydroxylase activity was reduced, and the plasma Ca level was particularly low, in chicks on the low protein/low Ca diet. The 24-hydroxylase activity was high on the low protein diets. It was concluded that adaptation to a low protein diet occurs over the first 4 days and that this may be associated with the high growth hormone level and also that adequate dietary protein is essential for maximal adaptation to dietary Ca deficiency.
authors.affiliation: Department of Animal Physiology & Nutrition, University of Leeds, England.
authors.forename: B A
authors.initials: BA
authors.lastname: Sommerville
authors.forename: S
authors.initials: S
authors.lastname: Harvey
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3; D000818:Animals; D002118:Calcium / Q000008:administration & dosage* / Q000097:blood; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004100:Dihydroxycholecalciferols / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D008297:Male; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D004100:Dihydroxycholecalciferols; D014807:Vitamin D; D015650:24,25-Dihydroxyvitamin D 3; D013006:Growth Hormone; D002118:Calcium