«Minimising slurry pooling in dairy housing 2 Minimising slurry pooling in dairy housing Contents Slurry pooling – an introduction 4 Design and ...»
pooling in dairy housing
2 Minimising slurry pooling in dairy housing
Slurry pooling – an introduction 4
Design and management factors which contribute to clean and healthy cows 5
Digital dermatitis 5
Building layout 6 Floor design and maintenance 7 Feed passage 8 Access passages 10 Water 11 Ventilation 12 Other considerations 13 Slurry removal systems 14 Tractor scraped passages 14 Automatic scraper 14 Cubicles with flush wash passages 15 Minimising the slurry tide 17 Minimising slurry build-up at the end of the scrape 20 Good practice guidelines – straw/loose yards 23 Good practice guidelines – cubicles 25 Collecting areas and dispersal 27 Handling and treatment areas 28 Background information 29 Glossary 30 How does your dairy unit shape up? 31 Assessment forms 32 Straw yards with tractor scraped feed passages 33 Cubicles with tractor scraped passages 35 Cubicles with flush floor passages 37 Cubicles with automatically scraped passages 39 Cubicles with slatted passages 41
A 700kg cow produces in excess of 60 litres of slurry per day, most of which will be deposited in feed and cubicle access passages.
Where you have cows you will also have slurry. Management practices relating to this ‘waste’ and its potential to stand or pool has an effect on cow cleanliness and, thus, increased infection pressure on both feet and udder.
This document uses on farm experiences combined with practical tools to help you assess your own unit. It then provides guidance on areas which may require attention.
• Slurry pooling occurs as a result of poor site levels, poor link levels, inadequate slopes and a lack of maintenance
• Flat flooring can increase slurry pooling, especially where automatic scrapers are installed
• Slurry pooling can range in severity from areas that are largely affected to more localised areas
• Standing space per cow and frequency of scraping are the key contributors that result in slurry pooling.
More in-depth information on housing and floor design is provided in DairyCo’s publication ‘Dairy Housing – a best practice guide’.
4 Minimising slurry pooling in dairy housing Design and management factors which contribute to clean and healthy cows Many factors contribute to clean and healthy cows, including housing design which can have a direct and indirect influence on cow health, including lameness and mastitis.
Slurry depth in buildings has a major influence on the incidence of digital dermatitis in housed cattle. This is especially true if the slurry depth is consistently above the coronary band of the cow’s foot (where the skin/ hair of the leg meets the hoof), generally around 25mm above floor level.
Digital dermatitis Digital dermatitis is a highly contagious, erosive infection usually affecting the skin on the bulbs of the heel but it can also be found between the digits or in the area of the coronary band. The disease is often more prevalent in housed herds with poor hygiene and wet conditions. Digital dermatitis causes pain and discomfort and can result in lameness. Digital dermatitis thrives in damp dirty conditions, so keeping passageways clean and minimising cow contact with slurry reduces the risk of infection. Digital dermatitis
A two-row cubicle arrangement (two-rows of cubicles accessing one feed passage) has more passage space per cow than a three-row arrangement (three-rows of cubicles accessing one feed passage). Typical two and three-row arrangements are shown in figures 1 and 2 respectively.
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A two-row system has 20% more surface area than a three-row system. This means that the accumulated slurry is distributed over a larger surface area in the two-row system helping to reduce the depth of the accumulated waste.
A tight three-row arrangement with a 3m wide feed passage, 2.1m cubicle access passages, will create an average slurry depth of 24mm over 24 hours. A generous two-row layout with a 5m wide feed passage and 4m wide cubicle access passage, creates a reduced average slurry depth of 11mm over 24 hours. This is less than half the average slurry depth of the tight three-row unit.
Farmers who have installed wide passages do not regret the decision, while others using tight layouts may encounter problems such as negative aggression between cows. A short-term financial capital gain may contribute to a long-term financial loss.
Farmers using this information, which is based on a 700kg cow, should link it with other sources, such as legislation and quality assurance requirements, which are specific to their particular needs. It is important that cubicle dimensions are up to date and are suitable for the size of your cows.
6 Minimising slurry pooling in dairy housing Floor design and maintenance Floors must be properly drained and treated in such a way to prevent slipping, with a gentle gradient to provide good footing. A high standard of floor maintenance throughout any dairy unit is essential to avoid foot problems. Damaged floors (pits or holes) pool slurry and may cause injury.
A floor inspection and repair programme should be carried out rigorously each year.
Floor types and finishes Many variations are possible.
• Grooved slotted or grooved squared profiles should ideally not exceed 40mm apart, so ensuring that the pressure points of a cows’ foot will always land on a groove
• Hexagonal patterns should consist of regular hexagons with 46±4mm sides separated by grooves 10±1mm wide and a minimum 6mm deep.
An approach to avoid the harsh surface caused by rough tamping, is to finish off rough concrete with a stiff brush texture and groove later as the surface smoothes off. A very abrasive surface can increase the wear on hooves to a degree that can be detrimental to hoof health. Stamped patterns into wet concrete can create cambered bulges between the grooves. This creates a slippery floor, as feet slip into the grooves, causing claw damage.
• Avoid slippery floors by providing skid resistance for cattle walking in all directions and to eliminate the adverse effects of high pressures on the hoof
• Spilt sand when used as bedding can smooth off concrete floor surfaces, therefore, surface retexturing will be required more frequently when cubicles are bedded with sand
• Conversely, spreading a surface with sand when conditions are icy will help prevent cows slipping.
Hexagonal floor finish
A range of products are now available for solid and slatted floors. Hard rubber mats with no surface texture will become slippery. Textured rubber mats allow the foot to penetrate into the mat to provide grip.
Floor slopes to drains
• Slat quality must be good and slats must be laid carefully to avoid rocking or differences in level between adjacent panels
• If the floor is fully slatted, it should be laid flat or with a very slight slope, down the length of the building, to meet site levels
• Slats should be tractor bearing, with heavy weight-bearing slats at cross passages, to cope with feeding equipment.
Feed and access passage dimensions have the greatest influence on limiting slurry depths, which may affect the incidence of digital dermatitis within the herd.
The Red Tractor Scheme (2012) stipulates the feed face required per cow for simultaneous and ad-lib feeding. This is demonstrated in Table 1.
Providing adequate space at the feed face will result in less aggressive interactions, regular scraping will also reduce slurry depth. In systems where feed face space is restricted, the build-up of slurry on solid floors can occur rapidly and farmers should ensure that these areas are frequently scraped. In ad-lib feeding systems it is important to ensure that feed is regularly pushed up and within the reach of the cow, this will also help alleviate aggressive interactions at the feed face.
8 Minimising slurry pooling in dairy housing Table 1 – Feed face requirements (2012)
Feed passage widths Provide a feed passage at least 4.6m wide for a two-row cubicle system, this should be increased to 5.2m for a three-row system where one row of cows back out of cubicles into the feed passage.
Sloping feed passage
Slatted feed passage Slatted floors are often seen in feed passages. It is important that the slats are well constructed with no rough edges or abrasions.
Feed trough level The base of the feed trough should be approximately 10cm above front foot level to enable cows to gain maximum reach when feeding. A feed barrier sloped or set, 20 degrees from the vertical, away from the feed passage will also assist in this respect.
Feeding step Within automatically-scraped systems, cows can be disturbed by the scraper when they are eating. A feeding step will reduce the problem by keeping the front feet clear of the scraper blade.
A step size approximately 50-60cm wide, 10cm high, with a 3% slope draining towards the feed passage would suffice. The feed trough level should be raised, as previously stated, above the feeding step level, with feed barriers set to suit the new step height. Bullying at the feed face A feeding step at the barrier helps keep front feet clear of the scraper blade is reduced by the installation of feed dividers,
The purpose of a passage within a cubicle building is to facilitate cow movement, allow the cows to loaf and exhibit social interaction as well as allow the removal of slurry.
The following passage widths are suggested:
• Passage between rows of cubicles should be a minimum of 3.0m with an ideal width of 3.6m
• Cross-over passages without a water trough should be a minimum of 2.4m wide
• Cross-over passages with a water trough should be a minimum of 3.6m wide.
Passage width should be increased to suit cow size, ie additional space may be required for very large cows to access or exit a long run of cubicles. Make end cross passages wide enough to enable tractor scraping, this will also make it easier to locate scraped slurry collection grids and channels on the inside of gable end walls, without them interfering with cow flow across the building.
Pooling immediately adjacent to the cubicle step must be avoided because this area significantly influences cow cleanliness.
Slope solid passages 1.5-3% down the length of the building when automatically scraping, to help prevent widespread slurry pooling.
Sloping passages across the width Never slope a solid cubicle access passage towards a cubicle step, unless the pass is flush washed to encourage cleaning at this point. Keep the passage level across the width or with a slope away from the cubicle towards any central drainage channels.
Any flat passage will lead to pooling. One possibility is to create a slight fall of 2% towards the centre of the cubicle access passage. This will move liquids away from the cubicle step area.
Poor floor levels across a building can lead to slurry pooling as illustrated below
10 Minimising slurry pooling in dairy housing Cow flow All passages should be designed to ensure that there are no dead ends, where a dominant cow can interact aggressively with a subordinate cow.
Cubicle cross passages Provide a cross passage at least every 20 cubicles, for ease of cow movement.
Cross passage cleaning
Water Provide plenty of large water troughs, since high performance cows can drink up to five litres of water for each litre of milk produced. This is demonstrated in Table 2.
Table 2 – Daily drinking water requirements
• Multiple troughs per group are ideal for allowing subordinate cows access to water at all times
• A minimum of 10cm/cow drinking space is recommended and sufficient to allow 10% of the housed cattle to drink at any one time
• Trough capacity should be at least 300 litres, supplying at least 10 litres per minute
• Flow rate is very important because a high rate prevents cows having to queue for water
• Fast-flowing moderate capacity troughs are also easier to keep clean
• Provide ready access to water immediately pre- and post-milking
• Tipping troughs or troughs with large emptying valves onto cross passages, help keep them clean
• Beware of any potential frost problems in supply piping. Care should be taken to avoid ice patches when troughs are tipped in extreme weather conditions.
Water troughs should be located so that it is not possible for cows to drink while standing on bedded areas. This will either mean locating the water trough in the feed passage (which can create problems with feed contaminating the water trough) or on the edge of the bedded yard but protected by a block wall or similar.
Protected water trough in straw yard The water trough should not protrude into the feed passage as this will affect the ability to scrape the area completely. Ensure they are appropriately located for ease of cleaning and to keep blown straw out of the trough.
Ventilation Ensure good natural ventilation throughout the dairy unit in order to ensure a supply of clean, fresh air, exhaust waste gases and control humidity.
• Spaced roofing (10mm between each adjacent side sheet) is an excellent way of providing good natural ventilation, especially in large, multi-span dairy units
• Provide a generous airspace for cows to aid ventilation, at least 40m3 per cow for straw yards and 35m3 per cow for cubicles.