Rehman et al., J. Anim. Plant Sci. 23(4):2013 1008 ANTIMICROBIAL ACTIVITY OF MENTOFIN AND ITS EFFECT ON ANTIBODY RESPONSE OF BROILERS TO NEWCASTLE DISEASE VIRUS VACCINE S. R. Rehman, K. Muhammad, T. Yaqub * , M. S. Khan ** , K. Hanif and R. Yasmeen Department of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan * University Diagnostic Laboratory, University of Veterinary and Animal Sciences, Lahore, Pakistan ** Department of Clinical Medicine & Surgery, University of Veterinary and Animal Sciences, Lahore, Pakistan Corresponding author Email address: drkhushi.muhammad@uvas.edu.pk ABSTRACT Mentofin is a herbal product containing 10 % eucalyptus oil, 10% menthol, 33% liquid builders and 47% saponins. Its antimicrobial activity in vitro against Newcastle Disease (ND) virus and urease producing bacteria, and its effect on antibody response of broilers to Newcastle Disease (ND) virus vaccine were evaluated. Mentofin at 0.5 % concentration inactivated the lentogenic strain of ND virus within 15 minutes at interaction temperature of 37 0 C and at 0.01% inactivated Proteus vulgarus in nutrient broth while 0.0001% concentration inactivated the same bacteria in urease broth. For evaluating its effect on antibody response of broilers to ND virus vaccine, one hundred day old broiler chicks were divided in to four groups (A, B, C and D) with 25 birds in each. Each bird of group A and B was vaccinated against ND and each bird of group A and C was treated with Mentofin while birds of group D served as negative control. Anti-ND- HI antibody titer of all birds was monitored on 14, 21, 28 and 35 days of age. Mentofin treated broilers showed higher consistent antibody titer as compared to untreated broilers. These birds when given challenge infection on 35 days of age showed same protection as that of untreated vaccinated birds. However, un-vaccinated and Mentofin treated broilers showed higher protection than those of non-treated unvaccinated. Mentofin did not show any effect on weight gain and feed conversion ratio of the treated broilers. Moreover, droppings from Mentofin treated birds showed no urease producing bacteria while 100 percent droppings of the Mentofin untreated birds showed urease producing bacteria. Key words: Mentofin, anti-NDV HI antibody titer, FCR, Urease producing bacteria, Ammonia. INTRODUCTION Poultry sector is one of the important segments of agriculture industry of Pakistan. Broiler meat contributes 23.8 percent of the total meat production in the country (Economic Survey of Pakistan 2009-2010). The broilers suffer from co-infections resulting in significant economic losses due to high morbidity / mortality and higher feed conversion ratio (FCR) (Nili and Asasi, 2002; Ley, 2003). Immunity failure in chickens occurs quite often because of biological or chemicals induced immune suppression, variation of avian pathogens and irregular use of vaccines (Xie and Song, 2005). Immuno-suppressed flocks may have high susceptibility to secondary infections and poor feed conversion ratio and response to commonly used vaccines (Sharma et al., 2000). In poultry production, application of immunostimulants is an essential requirement to improve the immunity of broilers. Some herbal products whose mode of action is unknown, are effective immunopotentiating agents. Mentofin is one of such products containing 10 % eucalyptus oil, 10% menthol, 33% liquid builders and 47% saponins. It is used in poultry to reduce Escherichia coli (E. coli) related lesions, mortality with acute infectious bursal disease (IBD) and reactions of Newcastle disease (ND) vaccination. It has positive effect on weight gain and improves the FCR of broilers (Carli et al., 2008). It reduces the morbidity and specific lesions after infectious bronchitis virus (IBV) challenge infection (Barbour et al., 2008). Eucalyptus and peppermint oils potentiate both innate-cell mediated and humoral immune responses in chickens. Administrations of these volatile oils have a potent immunomodulatory effect on immune response of birds to vaccines (Awaad et al., 2010). Present study was therefore, designed to investigate the antimicrobial activity of Mentofin and its effect on antibody response of broilers to ND virus vaccine MATERIALS AND METHODS Source of chicks: One hundred day old broiler chicks were purchased from Big Bird Hatchery, Raiwind Road, Lahore and were transported to Animal House of Department of Microbiology, Faculty of Veterinary Science (FVS), University of Veterinary and Animal Sciences (UVAS), Lahore. Experimental design: The broiler chicks were divided into 4 groups (A, B, C and D) with 25 birds in each. All groups were kept in separate cages in the same room. All The Journal of Animal & Plant Sciences, 23(4): 2013, Page: 1008-1011 ISSN: 1018-7081