Vitamin A dietary supplementation reduces the mortality of velogenic Newcastle disease significantly in cockerels.

This project was undertaken to find ways of reducing mortalities and economic losses due to velogenic Newcastle disease (VND) in areas where the disease is enzootic. Four groups of cockerels of 44 birds each were used for this experiment. The birds in groups 1 and 2 received no dietary vitamin A supplementation, whereas groups 3 and 4 received 300 iu and 600 iu of vitamin A per kilogram of commercial feed, respectively, from 1 week of age till the end of the experiment. At 6 weeks of age, the birds in groups 2, 3 and 4 were inoculated intraocularly with a VND virus (duck/Nigeria/Plateau/Kuru/113/1991). The birds in Group 1 were given phosphate-buffered saline intraocularly. Clinical signs appeared in Group 2 birds on day 3 PI and in groups 3 and 4 on day 5 PI. The clinical signs included a drop in feed and water consumption, depression, diarrhoea, torticollis and paralysis in all the infected groups. The average body weights of all groups were significantly different from one another on day 14 PI with Group 2 birds having the lowest body weight. Mortalities were highest in Group 2 birds (0%, 93.18%, 72.73% and 56.82% in groups 1, 2, 3 and 4 respectively). The antibody response in all the groups was significantly different from one another on days 14 and 21 PI. Group 2 birds had the lowest titres on those 2 days and showed more severe atrophy of the bursa, spleen, thymus and fibrin deposition in the spleen and thymus than the birds in groups 3 and 4. The above observations show that vitamin A dietary supplementation delayed the onset of clinical signs and significantly reduced body weight loss, atrophy of the bursa, spleen and thymus, and mortalities by 36%. It also significantly potentiated haemagglutination inhibition antibody response.