Immune-potentiation effect of commercially available products containing beta-glucans (betaplex and catalyzer) and nucleotides (electroimmune and avimmune) in the broilers was evaluated. A total of 120 broiler chicks were reared under standard husbandry conditions. The birds were vaccinated by live NDV vaccine at 5, 14 days and killed Newcastle disease virus (NDV) vaccine at 7 days of age. Additionally, live infectious bronchitis and infectious bursal disease vaccines were also given through water at 5 and 10 days of age, respectively. The birds were randomly divided into six groups each comprising 20 birds. Four groups (treatment groups) were offered four commercial immune-booster products at 7, 14 and 21 days of age for 72 hours. Fifth group (untreated vaccinated) was not offered any drug while sixth group (untreated and unvaccinated) was not given any drug and also remained unvaccinated against NDV. Anti NDV antibodies were measured at 7, 14, 21 and 28 days of age and heterophil/lymphocyte (H/L) ratio was measured at 14, 21 and 28 days. Weight of immune organs and performance of birds was also measured from each group. Finally, 15 birds from each group were inoculated with virulent NDV through intranasal route at 28 days of age to assess the protection against challenge infection.
Mean GMT anti NDV antibody titers in vaccinated groups were 3.65 (±0.59) at one week of age which were raised to the levels of 5.85 (±0.88), 5.50 (±1.00), 6.10 (±0.64), 5.90 (±0.91) and 5.45 (±1.05) in the betaplex, catalyzer, electroimmune, avimmune, and untreated control groups, respectively. Maximum antibody titer was achieved in electroimmune treated group while minimum in the catalyser treated ones. In non-vaccinated control group the antibody titers were minimum in the beginning that reduced to negligible level at four weeks of age. The H:L ratio of
Summary
48
all treatment groups did not significantly vary at 14 days of age while at 21 and 28 days of age, the birds receiving electroimmune have significantly low H:L ratio in comparison to other treatment groups. Weight of liver and spleen in nucleotide treated groups was significantly higher than other treatment and control groups while there was no significant difference in the weight of bursa of fabricious in all treatment groups. Relative weight of all immune organs to the live body weight did not significantly vary in all treatment and control groups. Performance of the birds as a measure of feed conversion ratio (FCR) was highest in electroimmune treated birds. The challenge protection data shows that minimum mortality of 40 % (6/15) was observed in nucleotides treated groups while betaplex and catalyzer treatment groups have 47 % (7/15) and 53 % (8/15) mortality ratios in comparison to 60 % (9/15) mortality in untreated birds. Results of present study suggest that nucleotide or beta glucans supplementation in the diet have beneficial effects to enhance the humoral immune response and better bird performance in broilers. Use of these products not on delay the onset of clinical disease but also helpful in providing better protection against challenge to velogenic NDV.