Vitamin means vital amines. They are organic regulators of metabolism that are required in the daily diet of bird for normal growth and maintenance of the body. They are mediators of synthetic and degenerative processes and exercise catalytic functions in the body because many of them function as co-enzymes. The present study was conducted in 200 day-old Hubbard broiler chicks to knew the effect of supplementation of different levels of vitamins in broiler starter and broiler finisher ration. The supplemented ration tested were ration A (NRC), ration B (NRC+l0%) ration C (NRC+20%), and ration D (NRC+30%). The experiment had a completely randomized design.

The chicks were randomly divided into 4 major groups comprising 50 chicks each. Each major group was further sub-divided into 5 replicates containing 10 chicks each. The supplemental rations were prepared according to NRC (Nutrient Requirement of domestic animals, 1994) requirement and with the addition of 10%, 20% and 30% vitamin. The four treatments were allotted to different groups of birds at random. The chicks were housed in a room compartment provided with battery cages-Experimental room temperature was 95F(35C) in the first week and then it was reduced SF each week. The birds were offered experimental rations and fresh clean water at ad libitum. The overall results showed that weight gain, FCR, weight gain per unit protein intake, liver and gizzard showed significant difference among the treatments. However feed consumption, protein intake and heart weight showed non-significant difference. The incidence of deficiency diseases was observed to be 8, 2, 0 and 0 percent fed on ration A, B, C and D respectively. However there was no mortality in any group. Net profit gain was higher for ration "D".

These results might be on account that supplementation improved the digestibility of dietary organic matter, protein fed and nitrogen free extract, thereby resulting in better utilization of these nutrients that ended to better performance. So in conclusion dietary vitamin inadequacy suppressed broiler performance and impaired the cellular mediated immunity. The recommendations for vitamin requirements and vitamins supplementation practices vary considerably throughout the world. So the updates of vitamin requirements extensively used in NRC journals are not always based on recent experiments. There is therefore a danger, that requirements stated for some vitamins might not reflect the need of modern poultry.
CONCLUSION
1. Experimental diet consistently showed better performance so vitamins in control diet are not optimal.
2. Normal needs of the birds and the recommended levels of the vitamins vary considerably.
3. The Official recommendations of the NRC cover only the lowerst possible needs so we will have to add substantional safety margins in the ration.
4. Improved performance in this experiment enable us to consider that further research is required to discover more efficient modalities of vitamin supplementation.