Infectious bronchitis virus (IBV) is a significant poultry pathogen that causes millions of dollars of loss. The poultry birds are vaccinated against IBV. Yet it is difficult to control the disease if the maximum vaccine amount is not achieved.
The best immune status of poultry birds is the key to optimal growth. The current compromised health status of poultry is due to the maximum use of antibiotics. In such conditions, the birds are immunocompromised and cannot fight with the pathogen which leads to a disease outbreak. Herbal plants and their extracts are more effective for a better immune system. Liquorice extracts have some beneficial effects under such circumstances as well. Therefore, liquorice benefits poultry nutrition and has properties on the growth, better performance and immunity status of poultry.
A study was conducted, to determine the immunomodulatory effects of liquorice on broiler chicken vaccinated with infectious bronchitis live vaccine. Day-old (n=60) broiler chicks were assigned to four groups with 15 birds each. The three groups (A, B, C) were vaccinated with infectious bronchitis live vaccine and two groups (A, B) were supplemented with 0.1gm and 0.3gm of liquorice extract in one-litre drinking water whereas the fourth one was taken as control. Liquorice extract was prepared in 75 percent ethanol and then ethanol and water evaporated in rotatory evaporator. The broilers were reared on the floor provided with an ad libitum supply of feed and water. The broilers were vaccinated with live vaccine at a dose rate of 0.5 ml at 3rd and 17th day of age. Antibody titer was determined at 1, 14, 21, 28, 35, 42 days of age from four birds of each group. At the 42nd day of age, five birds were taken from each group to determine gross and histopathological lesions of immune organs. The results of the study indicated an increased antibody titer of liquorice supplemented groups.
The overall results of the present study indicated that liquorice extract increased antibody titer in vaccinated chickens with infectious bronchitis live vaccine. This high antibody titer, in turn, protects the birds from severe infections of infectious bronchitis. There were no histopathological changes observed due to liquorice and live vaccine in broiler birds.
HAFIZA QAMAR-UN-NISA AND AMIR MAJEED