Methane is one of the main greenhouse gasses produced by the dairy sector. It is for 85-90% produced in a cows’ rumen by metabolic organisms. The level of production depends on factors like feed strategy, management, but also genetic variation between cows. Cows that produce less methane per litre milk, can be identified as more efficient than others, as methane production is associated with energy loss.
Five test setups were designed and built:
Experiments with these setups were performed under controllable circumstances in an air quality lab. Hereby the influence of the position of the nose and the effect of ventilation in the building, were studied.The breathing behaviour and methane production of a cow was simulated by an artificial cow. With this device the amount of released methane was controlled and compared with the amount of measured methane by the setup. With this data, the recovery rate of a setup was determined.
The highest recovery rates were measured with setup 5. Results showed that 100% recovery was possible for flow rates between 100 and 200 m3h-1, were possible with this setup. Hereby setup 5 was most promising for further experiments in a commercial cubicle house.
From here on further research should focus on implementing setup 5 in a cubicle house. With help of the artificial cow, the performance of this setup under these circumstances could be determined. Besides that CFD simulations for this setup should be performed to optimize the air inlet of the setup. This can be done by optimizing the shape and placement of the air capturing areas, to achieve maximal breath air recovery with a minimal flow rate.
Furthermore a sampling strategy for sampling multiple hoods with minimal measurement equipment, needs to be developed when implementing multiple setups in a commercial house. The maximal sampling interval for captured air and sampling position(s) for house air need to be determined.
A sixth setup for cubicle house application was designed, whereby its’ functionality under cubicle house circumstances was taken into account. This setup was designed to be mounted on common used cubicle equipment and had large, flexible and transparent side panels that should have minimal influence on a cow’s behaviour. However experiments with real cows in a commercial cubicle house need to be performed to study the effect of this setup on their behaviour.