Effects of different levels of Niacin at Grower Period in Pullet Grown on the Bed on Performance and Antibody Titer of Newcastle Disease

In current study the effects of different levels of niacin ( at the fixed level of the tryptophan amino acid in hy-line w36 pullet on performance and immune system in Grower (7-12 wks) of age in an industrial farm with a capacity of 100 thousand pieces were carried out. Treatments included: 1 niacin level 5% less than the standard recommendation. 2, 3 and 4, Niacin level equal to standard recommendation, 5 and 10% higher than the standard levels respectively. Experiment was done in a completely randomized design in which every treatment included 3 replicates with 8334 pullets in each replicate. Feed intake and body weight gain were measured every two weeks for calculate the conversion ratio. At the beginning and end of test, in each replicate, blood collected to measure antibody again Newcastle disease. The results showed that treatment effects on feed intake were significant (P0.05). The highest and lowest antibody titer of Newcastle disease were observed in treatments 3 and 1 respectively (P