EFFECT OF BETAINE ON EGG PERFORMANCE AND SOME BLOOD CONSTITUENTS IN LAYING HENS REARED INDOOR UNDER NATURAL SUMMER TEMPERATURES AND VARYING LEVELS OF AIR AMMONIA

GUDEV, D., S. POPOVA-RALCHEVA, I. YANCHEV, P. MONEVA, E. PETKOV and M. IGNATOVA, 2011. Effect of betaine on egg performance and some blood constituents in laying hens reared indoor under natural summer temperatures and varying levels of air ammonia. Bulg. J. Agric. Sci., 17: 859-866 A research was initiated to determine the effect of supplemental dietary betaine on egg performance and some blood indices in 2-year-old laying hens reared under natural summer temperatures and varying ammonia levels. 99 laying hens were allocated into three groups: I - control; II - supplemented with 0.7 g/kg betaine and III - supplemented with 1.5 g/kg betaine. The hens were kept on deep litter in a windowless poultry house for 23 days. The results of this study indicated no change in terms of egg quality (albumen weight, albumen index, yolk weight, yolk index, yolk color score, Haugh unit, egg specific gravity), hematocrit and leukocyte counts. The hens given 0.7 g/kg supplemental dietary betaine had higher erythrocyte number (P<0.05) than those given 1.5 g/kg supplemental betaine. Feeding 1.5 g/kg supplemental betaine resulted in significant decrease of heterophil percentage (P<0.05) and increase of lymphocyte percentage (P<0.05) at d 22, when air ammonia level was 3 times higher than permitted. These changes in leukocyte subpopulations led to a decrease of heterophil/lymphocyte ratio. Plasma corticosterone levels at d 22 were lower in the I (P>0.05), II (P<0.05) and III group (P>0.05) relative to the correspondent values at d 8. Both levels of supplemented betaine increased (P<0.001) the average egg production. Our results suggest that supplemental betaine has a positive effect on egg performance in hens reared under high air ammonia conditions.