Experimental exposure of broiler chickens to boric acid to assess clinical signs and lesions of toxicosis.

One-day-old broiler chicks were housed on litter treated with 0, 0.9, 3.6, or 7.2 kg of boric acid per 9.3 m2 of floor space. After 15 days, average body weights were 340.7 g, 278.1 g, and 213.2 g for chickens exposed to 0, 3.6, and 7.2 kg boric acid/9.3 m2, respectively (P < or = 0.05). Feed conversion was 1.68 and 2.29 in chickens exposed to 0 and 7.2 kg boric acid/9.3 m2 (P < or = 0.05). In a second experiment, after birds ingested feed treated with 2500 and 5000 ppm of boric acid for 2 weeks, body weights were 254.8 g and 149.6 g, respectively. The chickens in the control group weighed an average of 285.0 g (P < or = 0.05). The 5000 ppm treatment group had a feed conversion of 1.70, vs. 1.45 in the controls (P < or = 0.05). A dose-related feathering abnormality was evident in treated chickens. No significant histopathologic changes were observed. Livability, weight gain, and feed conversion were not adversely affected in broilers as a result of exposure to litter treated with boric acid at recommended levels of 0.4-0.9 kg/9.3 m2.