Although many hoof problems that our dairy cows experience can be solved with timely hoof trimming and other dairy management factors that promote cow comfort, proper nutrition also has an impact on hoof health – particularly regarding laminitis.
Laminitis is an inflammation of the lamina or corium of the foot that is caused by a disturbance of the blood circulation in that sensitive area. This reduction of circulation will result in edema, hemorrhage, inflammation and breakdown of the corium tissue. On a white-legged Holstein it is very easy to spot even a mild case of laminitis – it’s that puffy, pinkness just above the hoof at the hairline.
Rumen acidosis is considered to be a predisposing cause of laminitis. When a cow has an acidotic rumen, certain substances are released into the bloodstream that interfere with the blood flow from arteries to veins. A cow’s foot happens to be very vulnerable to this inflammation. Laminitis in dairy cows and heifers is primarily a nutrition problem resulting in poor rumen function.
Insufficient dietary effective fiber leading to an acidotic rumen is the largest nutritional contributor to laminitis. Diets high in corn and corn silage are common in many areas of the country. The excessive feeding of corn silage in dairy diets has the effect of reducing particle length and effective fiber. The chop length of a corn crop will also have a profound effect on the pH level in the rumen. The rumen requires a fiber mat to function properly and a “lack of scratch fiber” will prevent the rumen papillae from working properly.
Keeping nutrient content of a ration within these following guidelines will help avoid acidosis and laminitis:
- Starch levels at 25 percent to 28 percent of feed dry matter intake
- Total NFC at 35 percent to 40 percent of dry matter
- Neutral detergent fiber at 30 percent dry matter
- Total moisture in ration not to exceed 60 percent
- Total fat from plant sources not to exceed 0.5 pounds
- Use a rumen-protected fat source if more energy is required rather than feeding more grain.
- Include organic mineral complexes such as zinc/methionine in the diet to improve hoof integrity. Twenty mg/cow/day of biotin has also been shown to reduce sole ulcers.
- Include a rumen buffer such as sodium bicarbonate at 4 to 10 ounces/day.
- Total crude protein in ration should remain around 17 percent with properly balanced amino acids.
- Focus on feeding high-quality forages to keep the rumen mat viable.
Rations high in grains and commodity byproducts such as distillers grains, wheat midds or hominy tend to have less effective fiber. Excessive levels of rapidly fermented carbohydrates will often result in high levels of lactic acid, which can diminish or stop the efficacy of the fiber-digesting bacteria. This unwanted level of lactic acid is what causes rumen acidosis.
Short particle length in a ration can come from finely chopped silages as well as extra fine grasses or hay. Unprocessed corn silage should be no less than 3/8 inch in length. Processed corn silage should be closer to ¾ inch in length.
Slug feeding indicates the cow does not receive a consistently balanced ration during the day. She may be getting a lot of grain at one feeding with less forage and she will be getting more forage later with less grain. Slug feeding greatly disrupts the microbial balance in the rumen, causing significant fluctuation in pH levels, and again contributing to acidosis.
Sorting of feed will also cause an imbalance in nutrition. Especially if forage tends to be long and overly mature, the cows will tend to push it aside in favor of smaller particles and grain.
When delivering feed to the herd, make sure to do the following:
- Avoid over-mixing of total mixed rations.
- Make sure the scales on the mixer are working correctly.
- Make sure cows have adequate feed bunk or stanchion space to eat.
- Make feed available to cows all day.
- Keep feeding schedules consistent.
- Use a particle separator to check the size of and length of silages and TMRs.
Rapid changes in the diet will cause rumen microbial populations to fluctuate, causing pH levels to fluctuate as well, and the rumen environment to become too acidic.
Wet feeds generally indicate that there will not be enough effective fiber in a ration since there is an inverse relationship of high moisture to particle length. If a cow must eat more than 3 pounds of feed to get 1 pound of dry matter, there is a good chance that the diet lacks enough effective fiber.
Prevention of laminitis is dependent upon good nutritional formulation and management. Often during the summer heat, cows’ feed intakes will decline, leading to acidotic rumens. Laminitis will develop in the early fall. What you see as laminitis today was caused by nutritional and management factors several weeks before. Maintaining rumen health in your cows during heat stress will reduce the potential for foot problems later in the lactation.
Lack of adequate fiber in a dairy diet can be caused by the following:
- Rations high in concentrates and grains
- Short particle length of forage
- Slug feeding
- Feed sorting
- Rapid changes in diet
- Wet feeds
Cows can develop laminitis at any stage of lactation but are most susceptible during early lactation. Feed rations balanced to support more than 80 or 90 pounds of milk production tend to have higher levels of non-fiber carbohydrates (NFC) – that part of the ration that is mostly grains or byproducts and low in effective fiber. There is a limit to how much NFC a cow can consume before the rumen becomes acidotic.
Other indicators that a herd may be prone to laminitis are a low milk butterfat test, extra sloppy and foul-smelling manure and poor cud chewing. Low effective fiber in a ration will prevent the bacteria responsible for fat synthesis from working efficiently. Low effective fiber will also cause manure to get looser. Any time your cows are at rest they should be chewing their cud. Cud chewing is an indicator of good rumen activity and the action of chewing creates more saliva, which is then used to buffer the rumen.