Effects on Chickens of Chronic Exposure to Mercury at Low Levels Through Dietary Fish Meal

Abstract

The effects of ingestion of low levels (0.014 and 0.018 p.p.m.) of mercury over prolonged periods by male and female birds of one broiler strain and three White Leghorn strains were studied. The sources of mercury were herring meals manufacutured from fish caught off the Pacific and Atlantic coasts of Canada and containing 0.22 and 0.17 p.p.m. respectively of mercury.The difference in concentrations of mercury in the two meals was reflected in differences in tissue concentrations of mercury of the birds fed the respective meals. Genetic differences in tissue accumulation of mercury were evident both in tissues which accumulated higher concentrations of mercury (feather, claw, kidney) as well as in muscle which accumulated relatively little. There was no apparent relationship between the incidence of mortality and tissue accumulation of mercury. Egg production and egg quality were unaffected by the source of herring meal in the diet. Most of the mercury in the eggs was present in the albumen and the overall average concentrations of 47 and 40 p.p.b. in the albumen and 16 and 15 p.p.b. in the yolks of the eggs from the hens fed the respective meals reflected the difference in the mercury concentration in the meals. The concentration of mercury in the eggs did not increase with the length of time during which the herring meals were fed. Fertility and hatchability of eggs were not affected by the source of herring meal fed.