Urine and faeces are main sources of ammonia at pig farms. The maximal concentration of ammonia in buildings should not exceed 10 ppm for piglets, 20 ppm for fatteners and sows. In the present experiment, the effect of a phytogenic supplement on the productive performance of fattening pigs, faeces composition, volatile ammonia concentration in pig houses and on the degree of lung damage in pigs was determined. Animals were housed in two identical piggeries with comparable total volume. Fattening was divided into two phases: from 30 kg to 70 kg and from 70 kg to 110 kg of body weight (BW). The first piggery was used to maintain the control group, which comprised fattening pigs fed complete feed mixtures with no additive. In the second building, the pigs were fed complete feed mixtures with a phytogenic supplement at 0.5 g ∙ kg-1. The phytogenic supplement had a beneficial effect on pig performance, e.g. BW (p < 0.05) and daily weight gain (p < 0.01) were significantly higher, while feed conversion ratio per kg weight gain was lower (p < 0.05) in animals receiving this additive in the feed. In addition, fattening pigs from the experimental group showed significantly higher meatiness (p < 0.01) compared with the control animals. Faeces of the fattening pigs from the experimental group contained a significantly higher nitrogen content (p < 0.01) (which can be indicative of reduced urease activity and retention of nitrogen in faeces in the form of urea). This was reflected by a reduced ammonia concentration in the facility housing the animals fed the diet with the phytogenic supplement, both in every measurement period and in the whole experimental period. The lower ammonia concentration reduced the degree of lung damage. In the fattening pigs from the experimental group, lung rejections were reduced by 17% compared to the control group.

24.2.2019