Thyroid function, growth hormone, and organ growth in broilers deficient in phosphorus.
The effects of a dietary P deficiency on thyroid function, serum growth hormone, and growth parameters in 10 to 29-day-old broiler cockerels was determined. Chicks fed severely P-deficient diets (.05% or .10% available P) grew more slowly and ate less feed than controls fed .65% P. The deficiency was also accompanied by hypercalcemia, hypophosphatemia, and decreases in percent bone ash, fat-free tibial weight, and tibial length and width. Increases in the relative weights of kidneys, hearts, and pituitary glands (.05% P only) occurred as well. Most of these changes occurred to a lesser extent or not at all in pair-fed controls, showing that they resulted specifically from the P deficiency and were not simply a result of reductions in feed intake. Phosphorus deficiency also was accompanied by peripheral edema and hydropericardium. Relative thyroid weight was unaffected. Serum triiodothyronine was consistently lower in the P-deficient chicks, although effects were significant only in one experiment. Thyroxine levels tended to be low also, but not consistently so. Serum growth hormone in P-deficient chicks in both studies was consistently lower than that in pair-fed controls, but this was significant only when .10% but not .05% available P was fed. The findings suggest that serum levels of both thyroid hormone and growth hormone are altered by P deficiency, but the results were not clearly definitive.
Parmer
T G
TG
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, CT 06510.
Carew
L B
LB
Alster
F A
FA
Scanes
C G
CG
D000818:Animals; D001835:Body Weight; D002645:Chickens; D013006:Growth Hormone / Q000097:blood*; D008297:Male; D009929:Organ Size; D010758:Phosphorus / Q000172:deficiency*; D011201:Poultry Diseases / Q000097:blood / Q000503:physiopathology*; D013963:Thyroid Hormones / Q000097:blood*
D013963:Thyroid Hormones; D010758:Phosphorus; D013006:Growth Hormone