Veterinarni Medicina, vol.50, no.9, pp.406-410, 2005 (SCI-Expanded)
The effects of humic acid on feed consumption, egg production, feed efficiency, egg weight and external and internal egg quality of laying hens were studied during feeding periods. A total of 180 (Hysex Brown) layers (36 weeks of age) were used in this experiment. There was one control and two experimental groups, each containing 60 hens and 4 subgroups. The experimental period lasted 16 weeks. At the end of the experiment, the supplementation of humic acid had a significant effect on feed consumption and feed efficiency. An increase in egg production was determined when humic acid was added to the diets at 30 g/t of feeds (91.70%) and 60 g/t of feeds (91.32%). There were no significant differences between the groups in egg shell thickness, egg shell breaking strength, yolk index, albumen index and Haugh unit. It can be therefore concluded that the dietary supplementation of humic acid at doses of 30 and 60 g/t feed can be used to improve egg production, egg weight and feed efficiency.