A two-year study focusing on bedding types and SCC in 325 herds in Wisconsin had a clear result: Herds using sand had less mastitis.

“Different pathogens thrive in different bedding types, and we need to be aware of that when managing for somatic cell count (SCC),” said Pamela Ruegg, D.V.M. at the University of Wisconsin. “Most pathogens are opportunistic and originate in the environment.” Ruegg was a presenter during the Four-State Dairy Nutrition Conference held earlier this year.

SCC in herds using sand averaged 198,000, herds using mattresses and bedding averaged 220,000, and herds using manure solids were at 248,000.

Herds using sand averaged 1.6 percent of cows not having their milk shipped and 4.5 percent of cows milking in less than four quarters; mattresses/bedding herds had 1.9 percent of cows not shipping milk and 4.8 percent of cows milking less than four quarters; and herds with manure solids had 2.4 percent of cows not shipping and 6.3 percent milking in three or fewer quarters.

Herds bedded with sand produced more milk not just based on actual milk production, but also because of a lower percentage of milk discarded and a lower percentage of cows with dry quarters.

“The best option by a long shot is sand, and clean sand is best. The second choice would be mattresses with wood products,” she said.

Ruegg said dairy producers are much more likely to choose a bedding based on their waste management options rather than mastitis control. But, she added, good bedding management is critical no matter what type of bedding is used.

Ruegg said keeping sand dry is very important to keeping SCC low, which will help to reduce strep. “Reducing moisture in bedding is one of the most critical things you can do,” Ruegg said. The surface of sand bedding often dries out in the stall, and it is important not to add moisture to the bedding through excessive use of sprinklers or by using wet recycled sand.

All bedding sources, including wood products, should be kept as dry as possible.

Although the majority of producers using sand bedding say they never have completely dug out their sand stalls, Ruegg said, “At some point all sand needs to be cleaned out.” The frequency of cleaning out sand will vary depending on moisture content, consistency of the sand and characteristics of the stalls.

Producers should monitor the buildup of organic matter in sand and remove it when organic matter clearly accumulates – this is often visible as a dark line of organic matter as you dig down into the back of sand-bedded stalls.

Keeping bedding, cows and udders clean is important to reduce the frequency of mastitis. Stalls need to be cleaned frequently. Sand-bedded stalls need to be well-maintained and kept level.

Overcrowding also increases mastitis risks. Ruegg said cows in loose housing should have 100 square feet of bedding per cow and no more than 15 percent overstock.

Studies show for deep-bedding sand herds, there was no apparent advantage to adding sand more than once or twice a week. For herds with mattresses and bedding, there was no apparent advantage to frequent bedding replacement.

Although exposure to streptococci is high on all bedding types, exposure to coliform bacteria is more than 100 times greater with organic bedding (manure solids).

Whatever is in the bedding gets on the teats, but exposure doesn’t always equal infection. Many factors can increase a cow’s risk of infection, including leaking milk, wide teat apex, history of clinical mastitis and cows in third or later lactation.

Older cows have twice the risk of clinical mastitis, and cows with a history of clinical mastitis in previous lactations have a four-times-greater risk. Producers should cull cows that are leakers, which significantly increases the risk of mastitis, and have recurrent mastitis.

Provide lower-risk bedding – such as clean, dry sand – to fresh cows, especially during the first seven days of lactation. The first week after calving has the highest risk of mastitis pathogen infection. Ruegg said not to calve on bedding you wouldn’t be OK with lying down on yourself.

“We’ve been breeding cows for high yield and fast milking, but we inadvertently increased the cow’s predilection to environmental pathogens,” Ruegg said. Select cows with smaller udders and narrower teats to reduce exposure of pathogens.

From 1995 to 2015, the average herd size in Wisconsin changed from 50 cows to 186 cows, and milk yield increased 11 pounds per cow per day. Overall SCC decreased from 320,000 to 204,000, but there was an increase in clinical mastitis case rates from 13 to 24 percent.

Ruegg said there have been tremendous changes in the pathogens that cause mastitis. “Strep agalactiae is virtually eradicated, and staph aureus is highly controlled,” she said. “There is no reason to have strep agalactiae on a farm today.”

E. coli is the most commonly recovered mastitis pathogen on many large dairy farms, and environmental streptococci usually cause about 20 to 25 percent of cases.

Milking protocol and teat washing should be closely monitored on farms that have SCC and mastitis issues.  

For more information, visit Milk Quality - University of Wisconsin.

Kelli Boylen is a freelance writer based in Waterville, Iowa.