The effects of light on degradation of chloroteracycline (CTC) and oxytetmcyline(OTC) in chicken feces was studied, and the degradation velocity of CTC and OTC was determined by HPLC. The chicken feces were randomly assigned into two groups. One was in photophobic condition and the other was exposed to light. Samples were respectively collected from the two groups on day 0, 0.5, 1, 2, 3, 5, 7, 9, 12, 15 and analyzed by HPLC. In photophobic condition, the degradation velocity of three levels of OTC and CTC in chicken feces were 5.67%, 6.05%,...