Effects of feeds, supplemented with humic substances and calcium carbonate, on performance, egg quality and heart rate variability in laying hens

This study aimed to determine the effects of in-feed inclusion of humic substances (HS) and/or calcium carbonate (CaCO۳) on the performance and welfare of laying hens. A total number of ۱۴۴ Hy-Line Brown laying hens (۵۵ weeks old) were randomly assigned to four treatments, T۱–T۴ (۳۶ birds per treatment). T۱ hens were fed on a control diet without HS or CaCO۳, T۲ hens were fed on the control diet + ۲.۰۰ g per bird per day CaCO۳, T۳ hens were fed on the control diet + ۰.۲۰% HS and T۴ hens were fed on the control diet + ۰.۲۰% HS + ۲.۰۰ g/bird/day CaCO۳. The experiment started after ۱۵ days of adaptation and lasted ۸ weeks. The parameters evaluated were percentage of hen-day egg production, food consumption, mortality, egg quality parameters and heart rate variability (welfare indicator). Hens in the T۳ group showed a significantly lower feed intake than those in the other three groups, however, significantly higher daily egg production was recorded in groups T۳ and T۴ compared to T۱ and T۲. Eggshell quality characteristics were significantly improved by HS supplementation and eggs laid by hens in groups T۱, and T۴ presented paler yolk and shell color than those in the other groups. In conclusion, these results indicated that in-feed inclusion of HS had a beneficial effect on laying hens’ productive performance including egg production and eggshells quality.

کلیدواژه ها:

Eggshell ، Feed additive ، Sympathovagal balance