Ammonia mitigation and welfare enhancement in broilers using zeolite–clay–rice husk ash bedding supplement

Ammonia (NH₃) accumulation in broiler houses poses serious environmental and welfare challenges, causing respiratory irritation, impaired immunity, and footpad dermatitis. To address the limited long-term effectiveness of conventional materials like rice husk, this study evaluated a novel zeolite-clay-rice husk ash (ZCR) bedding formulation on broiler performance, welfare, litter quality, and in-house ammonia concentrations under commercial-like conditions. A total of 476, female Ross 308 broilers were randomly allocated to four treatments following a completely randomized design (seven replicate pens per treatment): control (5 cm thickness of rice husk, T1) or rice husk supplemented with ZCR bedding formulation at 10 % (T2), 20 % (T3), or 40 % (T4) of rice husk weight in T1 group. Birds were reared for 38 days in an evaporative-cooled house. Growth performance, including body weight, average daily gain, and feed conversion ratio, did not differ significantly among treatments (P > 0.05). In contrast, welfare indicators were significantly improved in birds reared on the 40 % ZCR bedding. Compared with the control, T4 birds exhibited lower heterophil-to-lymphocyte ratios, reduced serum cortisol concentrations (approximately 30 % reduction), and decreased footpad lesion severity (P < 0.05). T4 also maintained lower in-house NH₃ concentrations, reaching 50 % lower levels than the control at the end of the grow-out period. Litter collected at day 38 from ZCR-treated pens exhibited lower pH, reduced moisture content, and markedly lower NH₃ emissions. Correlation and orthogonal polynomial analyses further demonstrated dose-response relationships between graded ZCR inclusion, ammonia reduction, and welfare-related parameters. In conclusion, the novel ZCR bedding formulation effectively reduced NH₃ emissions, reduced physiological stress and improved broiler welfare without compromising growth performance. These benefits are particularly relevant for tropical poultry production systems, where high humidity accelerates litter degradation and NH₃ release.