Allow Organic Bedding to Work with Good Management

Mammary infection by environmental bacteria is a major mastitis concern. Productive dairy cows may spend more than half of the day with their udder and teats in contact with the resting surface. Increased bacteria populations in bedding material can increase bacteria counts on the udder increasing the chance of infection. Managing common bedding materials, the resting surface, and surrounding space to minimize environmental pathogen populations can lead to cleaner cows, increased comfort, and better udder health.

Bacteria require nutrients, moisture, proper temperature and pH to grow. Organic bedding materials, such as sawdust, shavings, straw, paper, hulls, and dried manure solids provide food needed for bacteria to thrive. Inorganic materials will not support bacteria growth. However, this is only true for washed sand free of organic matter. Recycled sand and sand stalls tainted with manure and milk provides nutrients for bacteria to grow. Sand is an excellent bedding alternative, but not all housing and manure handling systems (or dairy producers) are able to adapt to the „challenges? it can present.

Understanding the characteristics various organic bedding materials, and their ability to support bacteria growth, can provide clues to how much and how often bedding should be replaced. Softwood sawdust and shavings are preferred over hardwood since they contain resins that may inhibit bacteria growth. Paper is mostly cellulose and low in available nutrients bacteria may utilize. Straw and hulls (peanut, sunflower, oat) contain an abundance of sugars, starches and amino acids, so are potentially more able to support bacterial growth. While very high bacteria populations can be found in straw, hull, and dried manure solids samples, these materials can still be used satisfactorily with good stall bedding management and milking hygiene.

The most rapid period of bacteria growth in bedding materials seems to be 24 to 48 hours after being added to the stall. Studies suggest resting surface bacteria populations should be less than one million colony forming units per cubic centimeter (cfu/cc) to minimize udder infections. Most common organic bedding materials – even dry manure solids – can have very low bacteria populations when applied to the stall surface, but given the right conditions can spike rapidly. Bedding mixed with manure tracked into the stall, leaked milk, and moisture from the stall surface, respiration, and surrounding air allow bacteria populations increase rapidly.

Particle size is another important characteristic to keep in mind. Finely ground or chopped organic material favors rapid bacteria growth. It also has a greater tendency to stick to the udder and teats more readily. Improper milking prep may cause this fine material to enter the teat canal causing infection.

How should stalls be bedded? Jeff Reneau, Professor of Dairy Management, University of Minnesota suggests the following:

• Remove all used bedding from the rear half of the stall each day and replace it with fresh bedding.
  
• Don't move bedding from the front of the stall to the back of the stall.
  
• With stall mattresses and mats, use 1 to 2 pounds of fresh bedding, every day, making sure that the cleanest, driest bedding is beneath the udder.
  
• Once each week remove all bedding from the stall and replace it with fresh bedding.
  

A common bedding practice that should be avoided is to heap bedding at the stall front and rely on cow movement to move the material toward the rear. Studies indicate that by the time the bedding material finds its way to the rear of the stall – in the area of the teats and udder – it may contain tens of millions of bacteria.

Hydrated lime and other drying agents are often added to the bedding material and/or rear of the stall to control bacterial growth. One study indicated that adding approximately two pounds of hydrated lime to fresh sawdust at the rear one-third of the stall reduced bacteria growth for 24 hours. However, within 48 hours bacteria counts were similar to untreated sawdust.

The addition of manure to the stall surface promotes rapid bacteria growth. Therefore, anything that reduces contamination with manure (without affecting stall acceptance and use) will reduce bacteria populations. Other things to consider when developing a stall management strategy are:

• Crowding – Overcrowding increases the total amount of time stalls are used, manure, urine, and moisture in the animal space.
  
• Nutrition – 'High' group cows generally consume higher amounts of a nutrient dense ration that places more nutrient-dense manure into their environment.
  
• Stall cleaning – Remove manure and wet spots from the stalls at least every milking. A minimum of 3 times per day is highly recommended.
  
• Alley scraping – At least at every milking. Less manure in the cow alley = less manure tracked onto the stall surface.
  
• Moisture – Reduce the chance for moisture to accumulate on the alleys and stall surface. Adjust ventilation to keep floor and stall surfaces dry.
  
• Bedding storage – Keep bedding dry. Adding moisture to unused bedding increases bacteria growth before it even gets to the stall.
  
• Weather – Adjust bedding amount and frequency to weather conditions. Warm, moist periods require more frequent bedding removal and replacement.
  
• Bedding frequency – Change organic bedding at least every other day -- every day during summer.
  

A variety of organic bedding materials can– and are – used very successfully with dairy cows once the conditions that support the growth of environmental bacteria are understood and management adjustments are made to control them. The quote, “No farm ever went broke buying bedding”, still holds true. Some may challenge this statement given the recent shortage of good quality sawdust. However, it is hard to argue the importance of an adequate amount of clean bedding to the health and well-being of dairy cows. The benefits realized from increased comfort, improved cleanliness, reduced lameness and injuries, good udder health, and improved milk quality go a long way towards improving profitability. 

------- Dan McFarland, Sr. Extension Educator - Agricultural Engineering, York County