Evaluation of the effects of vaccination with a HVT-IBD vector vaccine on bursa Fabricii, production parameters and meat properties in broilers

ALONSO CASTRO Miguel, MERINO CABRlA David, FERNANDEZ GARCIA Domingo, TORRUBIA DIAZ Javier, HERRERA VIEJO Roberto,  FERNANDEZ REVUELTA Josè, MATEO OYAGÜE Javier,  CARVAJAL URUENA Ana, PRANDINI Francesco

 

Abstract

The objective of this field study was to assess the effects of vaccination with an HVT-IBD vector vaccine (Vaxxitek® HVT+IBD- MERIAL) on bursa Fabricii, productivity and meat properties, in comparison with an immunocomplex vaccine. The study was performed during 2012, in an area of Spain considered at high Gumboro disease pressure, in a total of about 800,000 broiler chickens distributed in two groups of 12 flocks each. Birds were ali vaccinated by in ovo route in the sa me hatchery: the first group with one dose of vector vaccine, the control group with one dose of IBDV-immunocomplex vaccine mixed with one dose of Herpes virus of turkey vaccine. Significantly higher bursa Fabricii weights were observed in the vector vaccine group, particularly in chickens 40-42 days old . ln the same flocks the lymphoid follicles had a larger size and a limited depletion versus control group demonstrating safety of the vector vaccine. ELISA test to measure antibodies against VP2 of IBDV at 22 days of age, showed higher level of antibodies in flocks vaccinated with the vector vaccine. Mean production and economie parameters were in ali cases favorable to the vector vaccine group, with 2,14% lower mortality, 0.02 points less in feed conversion index, 16 points higher in European performance index, and production cast of 1 Kg of meat resulted 0.014 € lower. At the slaughterhouse, the proportion of carcasses classified as first quality was 2,2% higher in the vector vaccine group. The associated economie improvement was of 0.036 € per broiler of 2.5 kg mean body weight. The present study demonstrated that the use of the vector vaccine, is associated with an improvement in production parameters at farm and slaughterhouse level in comparison with those obtained with an immunocomplex vaccine.

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