Problem solved through pump selection and spray direction.
A nozzle that sprays two mixed fluids produces a fine mist and does not clog easily, but the sound produced by the flow of air from such spray nozzles would cause your cows stress. Therefore, we suggest you use an airless type spray nozzle with an orifice diameter of about 0.4 mm. As a measure to counter clogging, you should use a spray nozzle that has a built-in compact filter. This will allow you to maintain a stable spray for long periods of time. We recommend that you operate the spray nozzles at a (rather high) water pressure of 5-7 MPa. Operating costs for your pump will not be too high because the flow rate is low. You can reduce the overall cost of the system if you install the spray nozzles in copper piping (lagged with vinyl) at ceiling level. A droplet of about 80 microns will evaporate before reaching the floor, and the temperature in your cowshed will decrease by some degrees due to the evaporation of the water droplets. It would be also very efficient to install a timer on the pump and to set it so that it sprays water at set intervals.