Sand bedding has largely replaced organic bedding for dairy cows. Typically, sand has a much lower level of pathogens than organic beddings such as straw or sawdust. If not stored and handled properly, sand can become contaminated.
Bedding, whether sand, straw, mattresses, sawdust, or other, is essential to cow comfort in free stalls. Cows should have comfortable stalls that encourage resting time. A typical schedule for a cow should be to stand and eat, stand to be milked, and spend the rest of the time lying down. The goal is to have a cow lay down in a dry, comfortable stall soon after eating or milking. Research conducted in Europe showed a 20 percent to 50 percent increase in blood flow to the udder of cows lying down versus standing. This is significant because it takes from 300-500 gallons of blood to flow through the udder for every gallon of milk produced. In comfortable stalls, cows may lay 60 percent of the time and seldom perch or stand idly by.
Comfort is an important goal, but so is sanitation in order to minimize udder infections. Organic beddings such as straw and sawdust offer a medium for bacterial growth, especially if allowed to get dirty and wet. Organic bedding materials may reach maximum bacterial populations 24 hours after they have been laid down. Sand, which is inorganic, is more resistant to bacterial growth. But it is not foolproof! Sand can become contaminated several ways. First, when sand is delivered, where is it stored? Is it allowed to be rained upon? Ideally, sand would be stored in a covered area. Does runoff from a barn lot, waste feed, or even manure come in contact with it? What happens after a hard rain? Does debris wash into the sand pile?
Sand can be contaminated in storage. But it can also become contaminated in the stall itself. Dr. Nigel Cook of the University of Wisconsin has sampled sand in freestalls for pathogens. Bacterial counts of coliform, environmental streptococci and staphylococci can all increase as sand becomes contaminated. Dr. Cook cites a case where a farm experienced a high rate of udder infections. Their normal bedding procedure was to add fine sand to their freestalls every 7 days with the beds leveled each day. Sampling showed a high bacterial count in the freestall sand. The existing sand was completely removed from the freestalls and replaced with coarse, washed, mason sand. Mastitis infections were halved within the month.
Sand bedding has been a huge boon to cow comfort and udder health (although not so great for equipment!). But sand is not a material to take for granted. Cleanliness and attention to detail both in the storage area and while in use must be observed.