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News and analysis on the global poultry
and animal feed industries.
on February 7, 2011

USPOULTRY releases recombinant laryngotracheitis vaccine study, paw burn study results

Recombinant vaccine may improve effectiveness when used in conjunction with modified-live virus vaccines

The U.S. Poultry & Egg Association has released the results of two of its latest studies: one entitled "Recombinant Laryngotracheitis Virus Vaccines: Evaluation of Effectiveness for Prevention of Disease in Commercial Broiler Chickens" and another entitled "Paw Burn Reduction in Broiler Chickens through the Use of Feed Grade Enzymes."

In the first project, the effectiveness of commercially-available, recombinant virus-vectored laryngotracheitis vaccines was compared to modified-live virus vaccines. Recombinant LT virus vaccines, when individually administered in ovo, had less protective immunity compared to conventional modified-live virus vaccines. Chickens vaccinated with both recombinant vaccines had similar protection compared to conventional CEO and TCO vaccine treatments, and absence of clinical LT signs and body weight depression. The conclusion was that recombinant virus-vectored vaccines may improve the safety and effectiveness of subsequent CEO vaccination by reducing numbers of birds with detectable LT virus in the trachea compared to CEO vaccination alone.

In the second project, trials were conducted to determine if feed-grade enzymes improve foot pad quality through a reduction in undigested complex carbohydrates being passed into the litter. Six commercial enzymes fed throughout the grow-out period did not improve foot pad quality scores in broilers, according to results, though improvements in intestinal viscosity were observed in most enzyme treatments. In addition, supplementation of broiler diets with high levels of biotin also resulted in no improvement of foot pad lesions. Overall, litter moisture was shown to have a substantial effect on the development of foot pad burns, indicating the importance of proper in-house environmental management.

The two studies are part of the USPOULTRY’s research program encompassing all phases of poultry and egg production and processing.

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