Slurry Management

Slurry will be removed from a housing system either by manual tractor scraping or by some form of automatic system. The automatic systems will either involve automatic scrapers or alternatively a flush wash system.

Removal of slurry with a tractor-mounted scraper is time consuming and will place a practical limit on the number of times each day that slurry will be removed. The operation can only be done when the cows are away from the housing.

 

On long cubicle runs, a number of 'bites' must be taken to avoid the wave of slurry contaminating the rear of the cubicle beds.

The installation of automatic scrapers has been linked to an increase in levels of digital dermatitis on many farms. This is assumed to be associated with the bow wave of slurry, which precedes the scraper blade. When the cow is familiar with the scraping system, she will wait until the blade is nearly on her foot before stepping over, leading to soiling of her foot and lower leg.

This effect is noted, apparently irrespective of the number of times the scraper operates.

Installing slatted floors or slatted cross passages, where slurry is deposited during the run, is beneficial. This avoids the accumulation of slurry and helps keep feet in good condition.

Automatic scrapers tend to be hydraulic, where the scraper blade sits on a saddle which moves around 1m every time the track is pushed forward by the ram. This system requires a track to be mounted on the scrape passage which can be problematic if manual scraping is required. The hydraulic scrapers also require the track to be kept clean in the summer to prevent a build up of slurry. The slurry layer on the track will cause the saddle to disengage from the track. The track is also not particularly kind to cows' feet.

Other scraper designs rely on chains, ropes or plastic coated wires. While these systems are kinder to cows' feet, particularly if the chain or rope is recessed into the floor, they require maintenance. Chains and ropes can stretch and break over time.

For more details on slurry management please see Dairy Housing - a best practice guide, chapter 12 slurry and waste management