ROXBURY – For dairy farmers, currently struggling under low milk prices, one of the ways to cope is to look for things in the dairy operation that are limiting cows’ performance. Correcting those problems is a way to make up for production that may have been lost if the herd has lost production because it can no longer use milk-boosting bST.
Dr. Nigel Cook, a veterinarian who has been with the University of Wisconsin for 19 years, says it’s worth identifying the rate-limiting things in the herd’s production, whether that involves feed, management practices, facilities or genetics.
He spoke to a group of dairy farmers at a meeting in Roxbury recently to talk about things he learned after poring over DHI records of 3,000 herds in the Upper Midwest. That study also included a visit to 66 elite herds in person to identify what managers there are doing right. Of these high-producing herds, 70 percent used deep loose bedding for their cows. Sand bedding, kept deeply piled in freestalls, was correlated with the most comfortable cows.
Cow comfort key
Cook said that 61 percent of these top-producing herds had two-row stall layouts in their freestall barns and all of them featured solid floors versus slatted floors (none had those.) Ninety percent of these elite performing herds also had fans over their resting area. Many provided cooling in the holding area.
Average lameness scores were 13 percent which is about the same as the best grazing herds in New Zealand, he said, and is better than dairies are doing in the United Kingdom and Germany.
Reducing lameness is one way get to better per-cow production. That might involve the cows spending less time on concrete – perhaps giving them time on pasture or dirt lots. Maintaining comfortable, well-designed stalls that are bedded deeply with sand and removing any existing restrictions all play into the highest production level for dairy cows.
Dairy scientists have watched grazing cows and noted the way that cows spend the hours in their day – they generally spend eight hours in the day eating which leaves the rest of the day for resting and getting milked. When cows are housed in freestalls we have to change that time budget, first of all because with TMR feeding that eating time is reduced from eight hours to about four or four and-a-half hours. “The cows now have an extra three and-a-half hours per day in her time budget.”
Sand is superior
Cook said cows in freestall barns need to rest 12 hours a day and will be most productive if they have that deep bedding, properly designed stalls, time available for resting and during hot weather, proper abatement of heat stress.
As farmers have heard before, sand is the best bedding for cows. Cook said using sand “promotes fewer but longer lying ‘bouts’. Cows are bony and lying on softer surfaces allows them to lie down longer. If those lying ‘bouts’ are longer she can take fewer of them.”
Sand has the benefit to cows of offering superior cushioning while also giving her traction and support as she gets up and down. “We want to create a place where cows get up and down naturally,” he added.
In a study of 141 dairy farms in Ontario, Canada cows that were bedded with sand spent 11.7 hours a day resting while cows housed with mattresses rested 10.5 hours per day. The shortest lying time was observed on waterbeds, he said, which were “worse than concrete” from the cow’s comfort perspective.
“Water beds are cushions when cows are lying on them but not when they’re getting up and down.”
That resulted in the average sand herd gaining 2,400 pounds of milk per cow per year over the others. In addition cows on sand had lower somatic cell counts.
Dairy barns in various parts of the world have freestalls that are bedded with other materials like straw mixed with lime or paper and lime. In Finland peat moss is used for bedding and here as in other parts of the world manure solids from a separator or a manure digester are used. Cook said that these solids provide a soft bed but are not quite the same as sand. Often this manure-based bedding is too wet, because drying costs money.
This can lead to bacterial growth, which can lead to high cell counts and potentially mastitis. “It has got to be drier,” he said. “Sixty to 70 percent moisture is just too wet.”
Getting that manure solids bedding down to 50 percent moisture makes it a lot better bedding, he said.
Cook recently spent time in California training third-party humane officials about what to look for in hock and knee scores. The worldwide average is 53 percent – meaning over half the cows in the herd have some hock or knee injury, sometimes resulting in open, weeping or swollen hocks. A much lower percentage is allowed in U.S. herds that are looking for a humane designation.
Rough surfaces in their beds can lead to hair loss and friction injuries in cows. Often, he said, mattresses have a surface that leads to these friction injuries in cows.
The reason hock injuries are important is because they correlate closely to lameness. “They go hand in hand; there’s a link here.” Once cows have sore hocks or other lameness issues there is a change in stall use behavior.
“Lame cows have longer lying bouts and they apply more pressure on the bony structures of their legs. They are reluctant to get up and this can even lead to recubitus ulcers.”
Lesions on the inside of the hock are generally because of poor design of the loops used in the freestall barn, he said. “I can design a really comfortable place for the cow to lie down but she needs to have time to be there too.”
Social pecking order
As we increase the time spent milking or waiting in a holding area, we decrease the time spent lying, he added. If cows have to wait too long to be milked, it can lead to some cows lying down in the fetching area. Subordinate cows can be pushed back by more dominant cows and end up not getting milked and back to their stalls as quickly.
In a survey of 50-60 robot milking farms in the Midwest, 30 percent lameness was not uncommon. Video of cows in robot systems, he said, showed some cows “got trapped” waiting to be milked because they were held back by the social pecking order in the herd and getting milked “was the only way out of cow prison.”
Overstocking pens is also a way to deprive cows of the proper amount of lying time in their day. There gets to be a “tipping point” Cook said, when overstocking and this lack of down time for the cow will result in loss of production.
We aren’t worrying about it now, but when warmer weather comes along heat stress is an important consideration for the dairy barn. “Cows generate a lot of heat. A 1200-pound cow produces nine times more heat than a human and twice as much as the 40-pound cow of previous generations,” he said.
The goal of mitigating heat stress is to “create a microclimate” in a freestall where the cow will lie down. Studies of cow measurements have found that after milking in the evening, cooling systems need run well into the night-time hours because cows are still hot after that last milking of the day.
“When she lies down, her body temperature rises about a degree per hour. As she stands she dissipates that heat by a half-degree per hour.” Because of that, hot weather can often cause a loss of that all-important lying down time in the cows’ day.
In a study of 30 cows during a heat spike, hot weather caused the loss of four hours of resting time. This constant standing to dissipate heat can also lead to lameness. Cook said cows prefer fast-moving air when they are hot; cooling systems that offer this to the cow will result in lower respiration rates.
“We want fast-moving air on the cow – 400 feet per minute – and we have to space the fans to get it on the cows. We want to bathe the cows in fast-moving air in their resting area.”
Cook suggests that it may be an improvement to use fewer fans in the end wall of the barn and put more fans on the cows. Getting more fast-moving air over the cows is preferable, even if it means reducing the tunnel ventilation and getting fewer air exchanges per hour.
Cook said the heifer barn is also a place to look in terms of increasing the herd’s production. Hoof trimmers are reporting, and he had seen himself, “corkscrewing” of the medial claw as well as thin soles on heifers, both of which can lead foot ulcers and lameness.
This phenomenon occurs mostly where heifers are being limit-fed, so they are pushing forward trying to get to their feed. As they do so, he explained, the outer claws of the heifers’ front feet aren’t touching the ground.
“This isn’t a wear issue; it’s a structural problem in heifer pens.” This problem is most pronounced in pens where heifers push against head locks or other vertical or slanted bars. Cook said he hasn’t seen the problem in pens where the neck rail is horizontal. “Headlocks increase the prevalence. As you provide a vertical bar this allows them to push against it.”
Heifers that develop this problem will have it for life, he said. “This changes the structure of the claw permanently. It doesn’t get better.”
Last year, a survey of 44 herds conducted scoring for this “reverse corkscrew” problem and 16 percent of the heifers have this problem. Scores ranged from zero to 75 percent. In the herds with the highest percentage of affected heifers, it was first apparent in growing age heifers and feed access was one of the contributing factors.
Cook was invited to speak to dairy farmers who work with Lodi Veterinary Care’s bovine practitioners.
By: Jan Shepel
Source: Wisconsin State Farmer