A Radioimmunoassay for Pancreatic-Glucagon in Chickens1

ABSTRACT A radioimmunoassay was evaluated for determining pancreatic glucagon in plasma of chickens. The sensitivity of the radioimmunoassay was 7.5 pg/ml at 95 % binding. Recovery of added porcine glucagon to chicken plasma samples had a correlation coefficient of 99.2%. Paral-lelism was demonstrated for the porcine glucagon standard and increasing aliquots of pooled chicken plasma which confirms the chicken pancreatic glucagon is immunologically similar to por-cine glucagon. Parallelism was also demonstrated between porcine glucagon and acid-ethanol ex-tracts of chicken pancreas (chicken pancreatic-glucagon). Since the cross-reactivity between acid-ethanol extracts of chicken pancreas and chicken intestine was only.03%, the antiserum is assumed to be highly specific for measuring chicken pancreatic glucagon. The pancreatic glucagon in plasma of 2-week-old broiler chicks given continuous light ranged from 325 pg/ml at 1930 hr to 850 pg/ml at 0130 hr. Chicks given a 14:10 hr light-dark period contained a low plasma glucagon concentra-tion of 390 pg/ml at 1630 hr and a high plasma glucagon concentration of 950 pg/ml at 0430 hr. Chicks fed 50 % and 75 % protein diets contained significantly (P<.05) increased levels (235 and 360 pg/ml, respectively) of plasma glucagon compared to chicks fed 25 % protein diets. Chicks fasted for 48 hr had an increase in plasma glucagon compared to chicks fed starter diets; however, the increase was not significant (P>.05)