Mike Hutjens is troubled by the growing number of lame cows he sees during dairy visits. Lameness, usually caused by laminitis, is on the rise and costing producers a lot of money, says Hutjens, University of Illinois extension dairy nutritionist.
In the Upper Midwest, a recent study showed that 20-25% of all cows are mildly lame. In a California study, researchers put the cost of mild lameness at $80/cow, says Hutjens.
Several factors contribute to an increase in the problem, including overcrowded and uncomfortable housing, rations lacking forage physical fiber and cows being pushed harder than ever to maximize production. That increase can also be attributed to dairy producers' accurate diagnoses using lameness or locomotion scoring.
With locomotion scoring, cows are each given a score from 1 to 5 based on how they walk and stand. A score of 1 is best; a 5 indicates that the cow is severely lame. (See accompanying story.)
In Illinois, where the average herd size is 100 cows, Hutjens encourages producers to score every cow. On dairies with hundreds of cows, he recommends scoring a representative sample from various groups, including high and low producers, heifers and dry cows.
On average, says Mike Socha, a Zinpro dairy nutritionist in Eden Prairie, MN, there's a 2% milk loss for cows with a lameness score of 2; a 4% loss if they score 3; 9% if they score 4; and 15% if they score 5.
Both nutritionists emphasize the importance of using foot baths, regular hoof trimming by professional trimmers to detect problems early and providing the most comfortable environment possible for cows. Adequate cooling and bedding, plus ample space for the cows to move and lie down, are keys to increasing cow comfort.
“A producer should have the person trimming the cows' hooves properly identify and record the lesions he or she is seeing,” Socha says. “Treatments vary depending on whether a lesion is infectious or non-infectious.”
Proper nutrition is a huge factor, too. According to Dave Combs, a University of Wisconsin dairy scientist, about 42% of the lameness cases identified by veterinarians are basically due to nutrition.
“Negative changes in rumen pH or other rumen dysfunction can disrupt the blood flow to the hooves, and that can lead to lameness,” says Hutjens.
To minimize that risk, feed high-quality, mold-free forages and maximize dry matter intake. He suggests using one of these two formulas:
“On a dry matter basis, the equivalent of 2% of a cow's body weight should be coming from forage sources that are chopped and/or processed correctly. For example, a 1,400-lb cow should be fed at least 28 lbs of forage/day,” he explains.
“Or, the equivalent of 1% of a cow's weight should be fed as forage NDF.”
For a 1,000-lb Jersey cow, that would be 10 lbs. “Divide the average NDF of your forages into 10 to get the number of pounds that should be fed on a dry matter basis. For example, if the forage is 45% NDF, I would divide 0.45 into 10 and that Jersey cow should be fed 22 lbs/day.”
“Our forages are changing; we want to make sure that they're behaving in the rumen the way we want them to,” says Hutjens, who says each cow should be fed 5 lbs of forage chopped at ¾-2" particle lengths.
Producers and nutritionists using Penn State Forage Particle Separators for corn silage chopped at ¾" theoretical lengths should see 10-15% of each sample in the top box and 50-60% in the middle box. For haylage stored in a bunker or bag, 30-40% of the sample should be in the top box and more than 40% in the middle box.
Hutjens also recommends that producers use caution if feeding forages with relative forage quality scores over 200.
“That type of hay is very, very digestible with high rates of passage. We have to be aware that we can almost make our forages too good, because they can pass through the rumen very quickly.”
Including a small amount of straw or high-quality grass in that type of ration can help slow rate of passage and add energy, he says. Consider including annual ryegrass, bromegrass, orchardgrass, perennial ryegrass, reed canarygrass, tall fescue or timothy.
Hutjens and Socha say proper amounts of trace minerals, including copper, magnesium and organic zinc, are needed, too.
“The link between good hoof quality and the inclusion of trace minerals in the ration has been proved in several studies,” says Socha.
Locomotion Scoring Easily Diagnoses Lameness
Locomotion scoring was developed several years ago at Michigan State University, but has been heavily championed by Zinpro the past few years, says Mike Hutjens, University of Illinois extension dairy nutritionist.
“It's a quick and easy way get a handle on the presence and severity of lameness in the herd,” he says. “In 10 minutes, we can train our students how to locomotion score, and they become very good at it.”
Here's how it's done: After watching a cow walk and stand, the observer assigns her a score of 1-5, with 1 being normal. It's given when a cow stands and walks normally with a level back and long, confident strides.
A score of 2 indicates mild lameness — when a cow stands with a flat back but arches as she walks. Her gait is slightly abnormal.
Moderately lame livestock rate scores of 3, stand and walk with arched backs and take short strides with one or more legs. A slight sinking of the dewclaws in the limb opposite the affected one may be evident in such a cow.
A score of 4 signifies lameness. It's given when the cow arches her back as she stands and walks, favoring one or more limbs, but still bearing some weight on them. A sinking of the dewclaws is evident in a limb opposite an affected one.
Severely lame cows get scores of 5; their backs show pronounced arching, and they're reluctant to move. The affected limb will carry little weight.