Effect of concentration of mixed-function oxidase on concentration of estrogen, rate of egg lay, eggshell thickness, and plasma calcium in laying hens

• Published in: Journal of animal science Vol. 71; no. 10; p. 2700
• Main Authors: Chen, S.W, Francis, B.M, Dziuk, P.J
• Format: Journal Article
• Language: English
• Published: United States 01.10.1993
• Subjects: Animals; CALCIO; CALCIUM; Calcium - blood; Chickens - blood; Chickens - physiology; Cytochrome P-450 Enzyme System - analysis; Dose-Response Relationship, Drug; Egg Shell - ultrastructure; ESTROGENOS; Estrogens - blood; Female; FEMELLE; FENOBARBITAL; FOIE; HEMBRA; HIGADO; Liver - drug effects; METALLOPROTEINE; METALPROTEINAS; Microsomes, Liver - enzymology; Mixed Function Oxygenases - physiology; OESTROGENE; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMICOS; Oviposition - physiology; OXIDORREDUCTASAS; OXYDOREDUCTASE; PERFORMANCE DE PONTE; PHENOBARBITAL; Phenobarbital - pharmacology; PLASMA SANGUIN; PLASMA SANGUINEO; POLLO; POULET; RENDIMIENTO EN LA POSTURA; TETRACHLORURE DE CARBONE; TETRACLORURO DE CARBONO
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/1993.71102700x

The objective of this study was to investigate the effect of induction or depression of mixed-function oxidases (MFO) by xenobiotics on the peripheral concentration of estrogens, plasma Ca, rate of egg lay, and eggshell thickness in laying hens. In Exp. 1, 100 mg of phenobarbital (PB) administered orally each day for 3 or 7 d reduced concentrations of estrone and estradiol (E2) in serum. In Exp. 2, 25, 50, or 100 mg of PB was administered orally to laying hens for 3 or 7 d. Treatment with 100 mg of PB for 3 d or with 25, 50, or 100 mg for 7 d significantly increased liver:body weight ratios. Microsomal protein increased after 7 d of 50 or 100 mg of PB administration. Feeding PB decreased concentration of E2 and total plasma Ca in a dose- and period-dependent manner. Concentration of E2 was reduced to 10% of control, whereas hepatic cytochrome P-450 increased significantly with dose. The correlation between concentration of E2 and P-450 was negative and significant. Total Ca in the plasma was highly, positively correlated with concentration of E2. Eggshells were thinner from hens treated with 100 mg of PB for both 3 or 7 d than those from control hens. Rate of egg lay was reduced by 100 mg of PB for 7 d. In Exp. 3, 0.5 mL of CCl(4) given orally for 1 d decreased P-450 and increased E2. These data indicate that effects on rate of egg lay, eggshell thickness, and plasma Ca by xenobiotics may be mediated through modification of MFO and the consequent change in concentration of estrogen