Effect of Dietary Calcium-Phosphorus Adjustment and/or Supplementation with Terephthalic Acid upon Serum Antibiotic Levels of Chickens

Abstract

It has been previously reported by Price et al. (1958a), using the ligated duodenal loop technique, that in chicks serum levels of oxytetracycline* (OTC) were significantly reduced by simultaneous administration of calcium chloride. Concurrent administration of calcium-binding agents, such as certain phosphates and citric acid, tended to overcome the depression in absorption produced by calcium. The fact that both calcium and phosphorus are present in poultry rations in fairly high concentrations suggested determining the influence of these elements on blood serum levels of orally administered tetracycline antibiotics. The effect of supplementing the ration with terephthalic acid (TA) also was determined, since Price et al. (1958b) have shown that TA markedly increases serum OTC levels in poultry by a mode of action apparently unrelated to cation depression of antibiotic absorption. This effect of TA is described in a recent patent (Kent and Peterson, 1958).In the present study, at least 5 …