Absorption of Chlortetracycline from the Alimentary Tract in White Leghorn Hens

IN AN attempt to increase control over poultry diseases, many investigations have been conducted concerning the potentiation of the tetracycline antibiotics in chickens. Several methods which have been proposed are highly effective under certain conditions. The addition of terephthalic acid has been found to increase the level of antibiotics in the blood two to three fold (Peterson, 1958). The source and the level of calcium in feed appear to have an influence on the absorption of the tetracycline antibiotics (Eoff et al., 1962). Harms and Waldroup (1961) found that a maximum antibiotic blood level in chicks could be attained if the calcium content of the feed was lowered slightly below the minimum requirements. However, Waldroup and Harms (1961) were able to detect only a slight increase in the oxytetracycline level in serum when low levels of calcium were fed to laying hens. In a more recent study Harms and Waldroup…