Studies on the Influence of Terephthalic Acid and Broad Spectrum Antibiotics on Egg Production and Egg Shell Coloration in Caged Layers

Abstract

TEREPHTHALIC ACID has been shown to increase the effectiveness of broad spectrum antibiotics in the domestic fowl. Terephthalic acid has increased the activity of the tetracycline antibiotics (oxytetracycline and chlortetracycline) in combatting certain diseases in poultry (Peterson, 1958, 1960; Peterson et al., 1959; Shelton and Olson, 1958). Reports by Peterson et al. (1959), Price et al. (1959) and Pensack et al. (1960) have shown that terephthalic acid fed with the tetracycline antibiotics (chlortetracycline and oxytetracycline) will increase the blood serum antibiotic level. The above studies mainly concern short term effects of terephthalic acid on antibiotic potentiation with little evidence of other physiological effects of terephthalic acid in the laying bird. In preliminary studies in this laboratory, a yellowish coloration was observed in egg shells from hens fed high levels of chlortetracycline. A review of previous work with antibiotics and terephthalic acid does not reveal any reported effect of the drugs …