20 June 2008

4 minute read

In my quest to improve my knowledge of the Dairy Industry, I went to the Sand Solution Conference in Wisconsin the week before Thanksgiving. This trip might have been more pleasant in the summer.

I was interested in what happens in the area of recycled sand and mastitis, and different ways of sand separation. Sand was separated from the manure by big screws on the dairy we visited and many neat innovations are being used to clean sand and the water used to separate the sand from the manure. This equipment looks expensive and has to be protected from freezing. Our long flush lanes make sand separating much easier.

What I did learn was, you need coarse sand to separate sand from manure with big screws. They prefer concrete sand, ASTM C33, because it has a large particle size which is needed for the big screws to pick up the sand out of the water. This is also the choice for bedding because smaller sand particles pack tighter together and don’t drain well and increase the bacterial levels of the bedding. The reason for the coarse sand being preferred for mastitis reduction is coarse sand does not pack like fine sand. Our Florida sand is very fine and packs and doesn’t drain. Many people have done bacteria loads in sand bedding, including us, and the results are all about the same.

Why do we bed with sand?

1. Its inorganic and does not support bacterial growth.
2. Cool in the summer, wicks moisture away from the cows skin.
3. Provides a soft place to lay.
4. Provides a secure surface for a cow to get up and down.

If sand is inorganic why does it have bacteria in it?

1. New sand comes from the ground. There are always bacteria in nature.
2. The cow is organic and has bacteria on her skin. Klebsiella, coliforms, streps and many other bacteria live in the gut and get on the body and are transferred to the sand.
3. Leaking milk may add bacteria but sure supports bacterial growth.
4. Recycled sand is washed with water either flush water or other water and it should have less than 1 % organic matter in it. Klebsiella and all these bad boys are in recycled flush water, that get in the beds due to foot traffic if cows are in the barn during flushing.

What levels of bacterial concentration will increase a cow’s chances of getting mastitis?

1. Most people are worried about the environmental bacteria, with the coliforms being the biggest worry. Cows die from the Klebsiella, E. Coil’s no matter what type of milking procedures you try. The streps seem to be controlled with a good pre milking sanitation.
2. The old rule of thumb has been that with a coliform count be under 1,000,000 CFUs per ml you should be safe. Our experience has been that we have seen big problems in that range. Wisconsin workers suggest this be 100,000 CFUs per ml.
3. Obviously bacteria multiply faster in warm temperatures. That’s why mastitis is higher in the summer or most of the year in the Southeastern US.
4. Recycled sand will have more organic matter (1%) than fresh sand so it will have faster bacterial growth than new sand.
5. For these reasons, in most cases re-bedding every 4 days or twice a week and leveling and fluffing stalls every milking or at least once a day will keep you in the safe range.

When should I remove all material in the back half of the stalls?

1. It should be removed when coliform counts hit 100,000 CFUs per ml, but in the Southeast at least twice a year (in April and October).
2. If you have real fine sand and it packs quicker, you may have to do it sooner.
3. I use a flat sided soil sampler that the side hinges up and you can see the wetness, color and texture for about 8” down. You can compare this to the front of stall. It’s pretty obvious, the smell will tell you.
4. A clam shell post-hole digger or a shovel will also do the job.

Overlooking the obvious: In all the years I have taken sand samples I have never written down how to take sand samples. Thanks to Dr. Nigel Cook from the UW Veterinary School for putting this in writing.

Methodology for collection of Bedding Culture Samples:

1. Wear latex gloves.
2. Sample the rear of approximately 10 stalls per pen – grabbing grossly uncontaminated bedding from the location of the udder.
3. Mix in a gallon Ziploc bag, sub-sample and freeze overnight.
4. Always compare used sand with fresh sand samples for a base-line.
5. Ship to the lab on ice.

Further Reading

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Find out more information on Mastitis by clicking here.

June 2008