*The study was subsidized by the European Social Fund (ESF) Arch. Tierz., Dummerstorf 49 (2006) Special Issue, 249-256 1 Chair of Animal Hygiene and Environment, Faculty of Animal Bioengineering, University of Warmia and Mazury in Olsztyn, Poland 2 Department of Forensic and Administration of Veterinary Medicine, Chair of Veterinary Protection of Public Health, University of Warmia and Mazury in Olsztyn, Poland DOROTA WITKOWSKA 1 , JANINA SOWIēSKA 1 , KRYSTYNA IWAēCZUK-CZERNIK 1 , TOMASZ MITUNIEWICZ 1 , ANNA WÓJCIK 1 and JÓZEF SZAREK 2 The effect of a disinfectant on the ammonia concentration on the surface of litter, air and the pathomorphological picture of kidneys and livers in broiler chickens* Abstract The study was conducted in order to determine the effect of a disinfectant on the level of ammonia on the surface of litter and air of henhouses as well as the pathomorphological picture of broiler chicken livers and kidneys. 240 meat-breed broilers (Cobb 500) were used in the study and divided into two identical groups, control and experimental – in which a disinfectant was used on the surface of litter (trade name Lubisan ® ). The study showed a significantly higher (p ≤ 0.01) concentration of ammonia on the surface of the control litter in comparison to the litter treated with the disinfectant. In addition, despite the absence of significant differences, the level of ammonia in the air in the control group was slightly higher. A pathomorphological examination revealed that there were 49% less deviations from standard in the internal organs of the experimental group chickens, with 55% less of such disorders in the kidneys and 39% less in the livers. It is noteworthy that there were significantly less (by 63%) regressive changes in the livers of chickens kept on the treated litter and that no inflammations occurred in the examined organs, which were recorded in the control group both in the kidneys and the livers. To summarise the results of this study, it can be said that the application of a disinfectant helps to reduce the concentration of ammonia on the surface of litter for poultry and to restrict the occurrence of morphological disorders in the livers and kidneys of broiler chickens. Key Words : broiler chickens, litter, disinfectant, ammonia, liver, kidneys. Introduction The ammonia which is emitted from poultry farms is an environmental problem everywhere in the world (SAPEK, 1995; KURVITS and MARTA, 1998; WATHES, 1998). Apart from that, it is considered to be one of the major stress causing microclimatic factors in poultry production. Excessive amounts reduce the birds’ productivity and deteriorates their health (AL MASHHADANI and BECK, 1985; TYMCZYNA and SABA, 1987). WATHES (1998) observed that when ammonia concentration was higher than 25 ppm, the growth of chickens was considerably slower. Other authors (AL HOMIDAN et al., 2003) found that health disorders might occur in birds when they are exposed to concentrations lower than 25 ppm NH 3 . WATHES et al. (2004) suggest that in order to improve birds’ welfare the acceptable concentration of 20 ppm of ammonia in poultry farms should be reduced to 10 ppm. Research has been conducted for many years into ways to reduce the amount of ammonia emitted for poultry litter. However, many of the preparations used in the past for reducing the amount or neutralising ammonia proved toxic or carcinogenic (TYMCZYNA, 1993; MOORE et al., 1996). Currently, there is a tendency to apply preparations which can be safely used in the presence of animals, without harming the environment. Among the range of additives, such as human preparations, aluminosilicates, saponins or microbiological substances (DOBRZAēSKI et al., 2000), there are also disinfectants. One of specific products, containing chloramine T and inorganic compounds together with essential oils, is a sanitising and disinfecting preparation with the trade name of Lubisan ® . It is intended for disinfecting rooms