Scientists based in Valencia have concluded that carbon dioxide balances are robust tools for determining the daily average ventilation flows on broiler farms. These balances could also be applied at more frequent intervals but in this case, particular care is necessary after light status changes because of discrepancies between animal activity and carbon dioxide production.

Carbon dioxide balances are useful in determining ventilation rates in livestock buildings, according to S. Calvet of the Universitat Politècnica of Valencia in Spain and co-authors there and at Germany's Georg-August University of Göttingen. In a paper published recently in Poultry Science, the researchers explain that these balances need an accurate estimation of the carbon dioxide produced by animals and their litter to determine the ventilation flows.

To estimate the daily variation in ventilation flow, it is necessary to precisely know the daily variation pattern of carbon dioxide production, which mainly depends on animal activity.

The objective of this study was to explore the applicability of carbon dioxide balances for determining ventilation flows in broiler buildings. More specifically, the work aimed to quantify the amount of carbon dioxide produced by the litter, as well as the amount of carbon dioxide produced by the broilers, as a function of productive parameters, and to analyse the influence of broiler activity on carbon dioxide emissions.

Gas concentrations and ventilation flows were simultaneously measured in three trials, with one under experimental conditions and the other two on a commercial broiler farm. In the experimental assay, broiler activity was also determined.

At the end of the experimental trial, on the day after the removal of the broilers, the litter accounted for 20 per cent of the total carbon dioxide produced, and the broilers produced 3.71 litres per hour (L/h) of carbon dioxide per kg of metabolic weight.

On the commercial farm, carbon dioxide production was the same for the two cycles (2.60L/h per kg of metabolic weight; P>0.05).

However, Calvet and co-authors noted substantial differences between carbon dioxide and broiler activity patterns after changes in light status. A regression model was used to explain these differences (R²=0.52). Carbon dioxide increased with bird activity, being on average 3.02L/h per kg of metabolic weight for inactive birds and 4.73L/h per kg of metabolic weight when bird activity was highest.

Reference

Calvet S., F. Estellés, M. Cambra-López, A.G. Torres and H.F.A. Van den Weghe. 2011. The influence of broiler activity, growth rate, and litter on carbon dioxide balances for the determination of ventilation flow rates in broiler production. Poultry Science. 90 (11) 2449-2458. doi:10.3382/ps.2011-01580

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