Effects of different levels of vitamin premix in finisher diets on performance, immuno - competence and meat lipid oxidation of chickens fed on corn - soybean meal

The present study was carried out to examine the effects of a vitamin premix (VP)reduction or withdrawal from finisher diet (29-43 days) on performance,immuno-competence,and characteristicsof leg bones and meat lipid oxidation of chickens fed oncorn-soybeanmeal based diet. A total of 900 male broiler chickens (Ross 308) were allocatedtofivetreatment groups(0, 33%, 66%, 100% and 133% VP), withninereplicates per treatmentgroup. At 29 and 36 days of ages, four birds from each replicate were injected with sheepredblood cells (SRBC). The cell-mediated immunity was determined via phytohemagglutinin(PHA) and 1-chloro 2-4-dinitrobenzen (DNCB)at 34 and 42 days of ages.At 33, 38 and 43days of age, 42 days of ages, and two birds of each replicate were slaughteredand boneparameters measured. The oxidative stability was evaluated by thiobarbituric acid reactivesubstances (TBARS) on the thigh samples that were stored for 90 day at-80 C. The resultsshowed that reduction or withdrawal of VP from diets at different time points of the finisherperiod did not affect performance, immunocompetence and characteristics of leg bones.Results of TBARS showed thatlipid peroxidation of the treatment without VP wassignificantly higher than of the other treatments when slaughtered at 43 days of age. Finally,the results of this study demonstrated that it is not possible to reduce the VP in finisherbroilers’ diets without negative effects on meat quality during the time of freezing.