Does Lime Stop Mastitis?

It may help but there’s more to good udder health than bedding

Does adding lime to your cows’ stalls prevent environmental mastitis? Milk producers often ask their veterinarians the question, especially at this time of year when cows spend more time in the barn. Research has tried to address this concern. As with all good research, however, it probably ends up posing more questions.

Here’s the environmental mastitis equation:

High numbers of bacteria + teat end entry + susceptible cow = new environmental mastitis infection.

To cause mastitis, bacteria in your cows’ environment must multiply rapidly and enter a susceptible cow’s teat ends. Given the opportunity, bacteria multiply to great numbers. If they gain access to teat ends, they are much more likely to be at a high enough concentration to cause mastitis. If good management keeps bacterial numbers low, and they are denied access to teat ends, then mastitis is prevented. Management of stalls and bedding influences the numbers of mastitis-causing bacteria in the cow’s environment.

Organic bedding—straw, sawdust, shavings and so forth—increases cow comfort. But it also provides feed and water for environmental bacteria. You have to find a careful balance between maximizing cow comfort and reducing this food and water source for bacteria for each facility, cow group and season.

Researchers have shown that adding hydrated lime to sawdust or shavings increased bedding pH and reduced its water content. This hindered bacterial multiplication. Daily replacement of sawdust in the back one-third of the stall also reduced bacterial numbers. One herd that changed bedding daily reduced clinical mastitis cases.

Researchers in a recent study compared the impact of lime and daily bedding replacement on the numbers and types of bacteria in sawdust and on teat ends (Bacteria Counts in Sawdust Bedding J. Dairy Sci 1997. 80:1600-1605 by J.S. Hogan and K.L. Smith). They created three groups of cows in their research herd’s tie-stall barn.

Group One: bedding replaced daily in the back one-third of the stall.
Group Two: one kilogram of hydrated lime spread over the sawdust in the back one-third of the stall every seven days.
Group Three: sawdust bedding changed every seven days with no other treatment.

All three groups had all bedding removed every seven days. Stalls were allowed to dry and then bedded with fresh sawdust. Bedding samples for counting bacteria were collected every week when the new bedding was put in stalls, and at one, two and six days after it was placed.

Adding lime to bedding reduced bacteria numbers in the bedding for Group Two cows, but the effect lasted less than 48 hours. By day six, bacteria counts were the same in all three groups. Moisture content of the bedding increased to the same degree in all three groups. Similarly, when the researchers examined bacteria numbers on teat ends, counts were slightly lower in Group Two, which got lime in the bedding, but this effect only lasted until the second day. The bacteria most reduced were the Klebsiella sp. and coliforms. However, even for these types, the effect lasted only a short time.

These results showed that adding lime to sawdust reduced the bacteria numbers in the bedding for one day. There was no impact on the bedding’s moisture content. Although previous research found replacing the bedding in the back one-third of the stall helped reduce bacteria, in this study it did not reduce the numbers of bacteria on the teat skin or in the bedding.

Two studies with opposite results? This suggests that on some farms bedding changes help. On others they make no difference. Studies done on large numbers of farms would have to be done to find out which farms benefit and why.

If you want to reduce clinical mastitis caused by bacteria that multiply in your cows’ environment, consider this research carefully. Differences in housing and management may overwhelm the effect of adding lime or making more frequent bedding changes on bacteria levels on a cow’s teat end. To reduce bacterial numbers effectively, you may have to change one or more aspects of your herd’s environment, such as:

  • ventilation;
  • cow housing density (cows per stall or per square foot of housing);
  • drier bedding storage;
  • barn design.

Until you reduce these major bottlenecks to mastitis control, relatively small changes, such as adding lime or changing bedding more frequently, may help a bit but won’t be enough to reduce mastitis.

Reducing bacteria numbers of bacteria in bedding is important but remember it’s only part of that environmental mastitis equation. Not only do you have to keep bacteria numbers low, but you must keep them out of the teat ends. Even herds with low bacteria levels will have more mastitis if they have highly susceptible teat ends or cows.

For more information:
Toll Free: 1-877-424-1300
Author: Dr. Ann Godkin - Veterinary Scientist/OMAFRA
Creation Date: May 1999
Last Reviewed: May 1999