EFFECT OF GRADED-LEVELS OF DIETARY NITRITE ON PULMONARY-HYPERTENSION IN BROILER-CHICKENS AND DILATORY CARDIOMYOPATHY IN TURKEY POULTS

In two separate trials, day-old broiler chicks and turkey poults were fed graded levels of dietary sodium nitrite in order to investigate th e possible role of nitrite-induced methaemoglobinaemia on the incidenc e of chicken pulmonary hypertension and spontaneous turkey cardiomyopa thy (STC). A transient low level of methaemoglobinaemia was observed a fter 7 days of exposure to dietary nitrite, but the levels returned to normal afterwards in spite of the presence of nitrite in the diet thr oughout the experiment. No effect on pulmonary hypertension, as measur ed by the right ventricle weight to total ventricle weight ratio, was observed in chickens exposed to dietary nitrite. The group of turkey p oults receiving 1200 mg/kg nitrite in the diet had a higher incidence of STC than controls (20 v. 5%), although the difference was not stati stically significant. The levels of nitrite-induced methaemoglobinaemi a were probably too low to be considered as the aetiology of increased STC incidence.