The birds that received Avatec at recommended dosage levels had higher body weight than the Clopidol medicated, Cyclophosphamide treated or untreated control birds.

Both Avatec and Clopidol treatments did not adversely affect the weights of bursa of Fabricius, spleen, thymus and liver of birds. Cyclophosphamide treatment of birds in early life resulted in.bursal atrophy and slight depression of splenic weight gain.

Avatec and Clopidol were immuno-stimulants and birds eating medicated rations had higher antibody titres as compared to control birds. The NDV vaccinated birds on Avatec and Clopidol medicated rations and those on non-medicated rations resisted challenge with a virulent ND virus, while the non-vaccinated birds of any treatment group and vaccine free control could not withstand this challenge.
Conclusions
This study indicated that Clopidol and Avatec, when used at recommended dosage levels (25 gm of Premix/50 kg of feed and 6.25 gm of pure drugl5O kg of feed respectively) did not interfere with the development of birds; did not have any adverse effects on weights of lymphoid organs such as bursa of Fabricius, spleen, thymus, liver; did not interfere with the development of humoral immunity in vaccinated birds. Their medication in feed rather produced beneficial effects on serum, weight gain and antibody production. The injection of Cyclophosphamide resulted in lower body weights, destruction of the bursa of Fabricius, poor antibody response of birds to vaccination against NDV, and very high post-challenge mortality.

The weight gain studies indicated that vaccinated and non- vaccinated birds on Clopidol and Avatec medicated feeds had non- significantly higher body weights that those on non-medicated ration at 56 days of age. Avatec at recommended dosage level, had more beneficial effects on the body weights than the Clopidol. These studies further indicated that vaccinated birds kept on Avatec medicated feed had significantly higher serum antibody titres on day 56 than the vaccinated non-medicated control birds.

From the results of this study it is concluded that Avatec and Clopidol are not immuno-suppressive drugs when used at recommended dosage levels. They rather have beneficial effects on growth performance and immune response of birds. However, there is a need for further investigations.