Sunday, December 10, 2023

Environmental effects on broiler mortality and growth

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ATLANTA — Does a cleaner growout environment produce a healthier chicken? Researchers with the Georgia Tech Research Institute’s (GTRI) Agricultural Technology Research Program are conducting an exploratory research project focused on answering that question.

“There is growing interest in eliminating the use of prophylactic antibiotics in livestock, and we began to wonder if good on-farm practices could lead to usage reductions,” says Robert Wallace, GTRI research scientist and project director. “A complementary consideration is what impact any changes in current practices could have on broiler mortality and growth rates.”

The research team has tested 1,280 broilers (chickens raised for their meat) during an entire growout cycle. The chickens were divided into groups and raised under varying treatments: new or used litter, with and without chlorine-treated water, and with and without antibiotic feed. Each treatment group was then analyzed in relation to the growth (final weight) and mortality rates.

The following results were found:

•              Water chlorination treatments had little effect on chicken growth and mortality independent of antibiotic feed treatments or litter condition.

•              Antibiotic feed had a negative effect (-2 percent) on growth in chickens raised with new, clean litter, but a positive effect (+4 percent) on those raised with used litter.

•              The highest weights were found in chickens raised with antibiotic feed and used litter (2.87 kg/chicken) closely followed by those raised without antibiotic feed and new litter (2.86 kg/chicken).

•              Higher mortality rates were found in the groups raised with antibiotic feed.

•              After considering group mortality rates, chickens raised without antibiotic feed and new litter yielded a greater net weight (+6.5 percent).

Indeed, results show a cleaner growout environment does produce a healthier chicken.

“Overall weights were comparable between animals raised on clean litter with no antibiotic feed compared to animals on used litter and given antibiotics. So, clean litter does reduce the need for antibiotics,” says Wallace. “Considering the lower mortality rates associated with clean litter, the largest remaining question is balancing the cost of more frequent litter changes versus antibiotic costs and consumer demands.”

The research team is currently investigating antibiotic resistance in both litter and animal gut flora, while further studying economically viable options for reducing or eliminating the use of prophylactic antibiotics. Longer-term goals involve exploring gene transport and the fate of antibiotics and resistant pathogens.

This research project is being conducted in collaboration with the Georgia Tech School of Civil and Environmental Engineering and the Department of Poultry Science at Auburn University.

Reprinted from PoultryTech, a publication of the Agricultural Technology Research Program of the Georgia Tech Research Institute, a program conducted in cooperation with the Georgia Poultry Federation with funding from the Georgia Legislature.

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