METABOLISM OF NARASIN IN CHICKENS AND JAPANESE-QUAIL

Thirty mature chicken hens and 60 mature Japanese quail hens were used to compare pathways of narasin excretion. Carbon-14-labeled narasin was injected into chickens (.7-mu-Ci) and quail (.113-mu-Ci) via cardiac puncture. Blood, sampled at varying times thereafter, and eggs and excreta collected daily for 28 days, were analyzed for C-14. Groups of six chickens and 12 quail were killed prior to [C-14]narasin injection and on Days 1, 7, 14, and 28 postinjection to obtain tissue samples for C-14 analysis. Blood rapidly cleared the label in both species. Less than 1% of the dose of [C-14]narasin remained in blood plasma after 3 h postinjection in both chickens and quail. Label excretion peaked on Day 1 in both species, and most of the C-14 was cleared via the excreta (76.7 and 93.6% of the dose for quail and chickens, respectively). Label appeared in the excreta more rapidly and cleared more quickly in quail than in chickens. After 24 h, 68 and 49% of the dose of [C-14] narasin appeared in the excreta of quail and chickens, respectively. More label was recovered in the eggs of quail (4.18% of the dose) than in the eggs of chickens (1.32% of the dose). Liver, heart, fat, and ovarian tissues contained traces of radioactivity 1 day postinjection in both species. Muscle and kidney did not contain detectable amounts of label. By Day 7, all tissue had cleared C-14 beyond detectable limits. The results indicate that chickens and quail metabolize [C-14]narasin via similar pathways and that excretion in quail may be more rapid than in chickens.