Culling: Impact of Feeding on Foot Health

Foot health or lameness has moved up to the second most expensive disorder that dairy cattle experience (mastitis is first). English workers reported 60 cases of lameness per 100 cows annually. Wisconsin researchers reported 73 cases per 100 cows in 30 herds (15 free-stall and 15 conventional herds averaging 23,060 pounds of milk). The cost was estimated at $122 per cow with lameness, hairy heel wart at $88 per case, sole ulcers at $369 per case, and horn disease at $227 per case. English workers measured a loss of 2.4 pounds of milk per day or 700 pounds per lactation per case of lameness. Foot disorders have increased recently for several reasons.

Poor records on farms did not reflect the extent of the problem.
Lameness definitions were not clear and easy to evaluate. Lameness scoring from 1 to 5 has simplified capturing data.
Hairy heel wart and foot rot were used as excuses for foot problems.
Cows are at great risk in large confinement operations exposed to concrete and higher culling rates.

One approach to solving foot disorders is to consider three factors that contribute to hoof disorders and increase culling. Cow factors included genetic selection of the foot (heel depth for example) and leg confirmation (set to the leg and correct leg position for example) can make the foot prone to lameness problems. The cow's environment needs more attention. Cow comfort, walking distances (from parlor to pasture or resting area), free stall surface and space, rubber walking surfaces, presence of small stones, heat stress, expose to manure and mud, frozen surfaces, and concrete are examples that increase foot disorders. Feeding is the third area that can impact foot health and is the focus of this article.

Laminitis Considerations

Wisconsin researchers suggested two causes of lameness in dairy cows: infectious agents and laminitis/feeding. Infectious agents cause 58 percent of cases including foot rot disease and hairy heel warts. Laminitis (contributes 42 of the lameness) is an inflammation in the foot causing disrupted blood flow to the corium. Several causes of laminitis can be found in research reports and field observations.

Blood histamine is increased after the death of gram-negative bacteria releasing endotoxin causing blood pooling in the claw. Protein degradation in the rumen also could contribute histamine.
Based on equine research, rumen acidosis produces a toxin with activates a metalloproteinase (MMP) that breakdown bonds between the epidermis of the hoof wall and soft tissue in the corium leading to sole ulcers and white line abscesses.
European workers suggest the production of lactic acids (strong acid) in the rumen due to low rumen pH shifting the rumen fermentation to rumen acidosis.

Rumen acidosis continues to be major factor in foot disorders as it causes laminitis. Factors that can lead to lower rumen pH include high levels of rumen fermentable starch and sugar, unsaturated fatty acids, high dry matter intakes, slug feeding of grain (over 5 to 7 pounds of dry matter per meal), forages lower in natural buffering capacity (such as corn silage), forages that are processed too short reducing cud chewing, wet rations, high quality pasture, and feed sorting (TMR) or selection (pasture).

Feeding Relationships

This section summarizes foot related feeding factors and guidelines to minimize the risk. Recommended levels are expressed as percent in the total ration on a 100 percent dry matter basis. Nutrients with little or no direct relationship to foot health included sodium, chloride, potassium, calcium, phosphorous, cobalt, and magnesium.

Starch and sugar are key factors leading to lower rumen pH and acidosis. These carbohydrates can shift fermentation away from fiber digestion and increase levels of propionic and lactic acids. Feed particle size (finely ground), processing (steam flaking), and starch source (wheat v corn) impact the rate of fermentation. Sugars have faster rates of rumen fermentation (found in high quality pasture for example). Suggested starch levels in the total ration dry matter is 25 to 28 percent starch and 2 to 4 percent sugar.

Protein quality and quantity can impact lameness. High levels of degradable protein and total protein may lead to rumen fermentation products that can impact foot health. Feeding 17 percent crude protein (Dairy NRC 2001) or 17.5% crude protein with 36 percent rumen undegraded protein (Dairy NRC 1989) is recommended levels.

Effective fiber maintains a rumen forage raft to optimize rate of passage and normal rumination (550 to 600 minutes of cud chewing activity daily). Rumen pH should be maintained above 5.9 (ideally 6.0 to 6.2). Five pounds of forage particles over one inch in length or 19 to 21 percent effective NDF.

Fats and oils can reduce fiber digestion and lower rumen pH due to depressing fiber digesting bacteria and lowering rumen pH. Unsaturated fatty acid can also changed to trans forms of the fatty acid if rumen pH is marginally low causing low milk fat tests. Add 2.5 percent as vegetable oil as oilseeds. Limit free vegetable oil to 225 gram per cow per day (corn distillers grain and extruded soybeans are examples). Limit fish oil to 50 grams per day. Rumen inert fat can be added to raise total fat levels from 6 to 7 percent.

Copper can impact the claw by increasing the production of a copper enzyme, thiol oxidate, increasing hoof hardness. Cattle deficient in copper were more susceptible to heel cracks, foot role, and sole abscesses. Suggested level of total copper in the ration dry matter is 10 to 15 ppm (1/3 from organic copper sources and 2/3 from inorganic copper sources). If total feed level of molybdenum is over 1 ppm, higher levels of supplemental copper will be needed.

Sulfur is needed for sulfur containing amino acids made by rumen bacteria (requires a ratio of 10 to 12 parts nitrogen to one part sulfur). Harder hooves have been reported with added sulfur in the ration. Recommended level of total ration sulfur is 0.25 to 0.28 percent.

Zinc improves claw integrity through wound healing, epithelium maintenance, and keratin synthesis and maturation. Pasture zinc levels vary with lowest levels in the spring lush growth period. Organic zinc can reduce somatic cell counts and increase milk production. Recommended levels in the total ration dry matter is 40 to 60 ppm (1/3 organic zinc sources and 2/3 inorganic zinc sources ).

Biotin is needed for keratin formation and claw horn development leading to foot disorders during deficiencies in cattle and horses. Recent studies at the University of Wisconsin supported earlier work from Ohio State University that biotin increased milk yield by 4 to 5 pounds. Milk production increases were not related to hoof improvement due to the immediate milk response. The mechanism for higher milk yield may be related to its metabolism function. Hoof improvement requires 6 to 8 months to observe a response. The recommended level of biotin is 20 milligram per cow per day at a cost 6 to 8 cents per day resulting in a benefit to cost ratio of six to one.

Scoring Lameness

Michigan State University developed a system of scoring lameness in cows from 1 to 5. Zinpro Corporation has published teaching guides for dairy farmers, veterinarians, and nutritionists to score cows.

Score 1: The cow's top line remain flat or level while standing and walking.

Score 2: The cow's top line remains flat while standing and humps while walking.

Score 3: The cow's top line is not level or is humped while standing and walking.

Score 4: The cow favors one or more feet.

Score 5: The cow is limping severely.

California field studies are summarized in Table 1. Herds should average less than 1.4 lameness score with percent of cows in each category listed in Table 1. Dairy cows with lameness scores of three or higher had dry matter reductions and lower milk yield.

Table 1. The impact of lameness on milk production and dry matter intake is listed by lameness scores.

Score	Percent of cows	Milk Drop (% of score 1)	Dry matter drop (% of score 1)
1	75	base	base
2	15	0	1
3	9	5	3
4	<0.5	17	7
5	<0.5	36	16

Take Home Messages

Lameness can lead to a loss of $122 per cow annually.
Genetics, cow comfort, and feeding will impact lameness.
Feeding programs can minimize lameness and risk to the hoof.
Lameness scoring should be conducted monthly to assess hoof and foot soundness with a herd less than 1.4 score average.

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Culling: Impact of Feeding on Foot Health

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