Biotin and hoof health

Hoof disorders are an insidious and costly problem in modern dairy herds. However, a growing body of scientific research is reporting significantly improved hoof health with dietary biotin supplementation. Other studies have found greater milk production and improved reproductive efficiency with dietary supplementation of this B vitamin. In all this work, the results suggest that the biotin status of unsupplemented dairy cattle, especially high-producing cows, may be marginal.

Of concern are both structural hoof abnormalities and the increased susceptibility to infections, such as heel warts and foot rot, that accompany compromised hoof and skin integrity. It's estimated that hoof disorders cost an average of $200 per case in treatment and lost milk production. Beyond the direct costs, the long-term costs include reduced fertility, early culling and decreased disease resistance. Although these latter costs are harder to quantify, Midla et al., (1997) noted that lameness is the third leading cause of involuntary culling in dairy herds, surpassed only by mastitis and reproductive failure.

Biotin has long been recognized as an essential nutrient for the formation of sound hoof horn, the modified epidermal tissue that forms the hard outer casing of the hoof wall and sole. Indeed, when researchers have induced clinical biotin deficiencies in calves, the signs have included soft, crumbling hooves along with skin lesions and hair loss. Biotin deficiencies in swine, poultry and horses have resulted in dermatitis and cracks and fissures in the feet and toes. Hoof and foot problems were reduced when these species received biotin supplementation in various research studies (Zenker et al., 1995).

More recent studies have shown that in dairy and beef cattle fed supplemental biotin, hoof health was improved and the incidence of the following common hoof problems was reduced:

• White line separation. In a clinical study with 100 first-lactation heifers, Midla  et al. (1997) reported that 27 percent of the unsupplemented control heifers had rear lateral white line separation and 20 percent of the controls had rear medial white line separation. In the heifers receiving 20 mg biotin per head daily, however, only 10 percent of the animals had rear lateral white line separation, and only 2 percent had rear medial white line separation. Differences were significant 100 days after supplementation began (100 days into lactation) (Figure 1).

• Sole ulcer or heel erosion. In a field study of 180 dairy cattle, Hagemeister (1996) reported that the animals receiving 10 mg per day of supplemental biotin had significantly less incidence of sole ulcers and heel erosion than unsupplemented controls. Fifteen months after the study began, 3 percent of unsupplemented cows had sole ulcers and heel horn erosion, compared to 2.3 percent of supplemented animals. Twenty-four months into the study, only 0.7 percent of supplemented cows had sole ulcer or heel erosion, compared to 3.3 percent of unsupplemented cows (Figure 2).

• Heel warts (interdigital dermatitis). Distl and Schmid (1994) reported 20 to 37 percent less incidence of interdigital dermatitis (heel warts) in cows receiving 20 mg of supplemental biotin per head daily than in unsupplemented controls during an 11-month study (Figure 3). Sole bruising also tended to decrease in supplemented cows. Hochstetter et al., (1996) also reported a reduction in digital dermatitis.

• Claw lesions. Lischer et al. (1996) reported a significant correlation between short-term healing of claw lesions and serum biotin levels, which had been elevated with dietary supplementation of 20 mg biotin per head daily. The rate of new horn formation over the lesions was significantly increased in supplemented cows (Figure 4).

• Sand cracks. Campbell et al. (1996) reported only half as many sand cracks in Hereford cows receiving 10 mg of supplemental biotin per head daily as in unsupplemented control cows. Incidence was 14.3 percent for supplemented cows and 29.4 percent for controls.

In all these studies, the interest in dietary supplemental biotin was prompted by two critical roles that the vitamin plays in the development of strong hoof horn tissue (Fritsche, 1990). First is in the differentiation of the epidermal cells that will become the hoof horn. Second is the production of keratin, a tough, insoluble protein that is the chief structural component of horn tissue (and of human fingernails as well). More recently, biotin supplementation has also been reported to stimulate the production of intracellular cementing substance (ICS), a combination of glycoproteins and complex lipids that bond horn cells and harden the horn tissue.

As the number of months in these studies suggests, the processes involved in hoof horn growth and regeneration are relatively slow. On the hoof wall, the horn is formed from cell layers near the top, just below the coronary band and in the region of the upper laminae. These cells gradually migrate down the front of the hoof, forming vertical tubules for structural strength. These are then hardened and cemented together by keratin and ICS. It takes 15 to 20 months for these cells to fully migrate down to the weight-bearing areas of the hoof.

The development of horn tissue on the sole is a similar process, although it takes only two to four months for the tissue to migrate down from the epidermal layers to reach the wearing surface. The white line, located around the circumference of the hoof, is the juncture between the horn-forming tissues of the hoof wall and sole. The horn cells here are not extruded in tubules as in the hoof walls, and the role of ICS becomes more crucial. This area is especially susceptible to physical damage and bacterial infection, as seen in the high incidence of white line separation that Midla et al. (1997) reported in unsupplemented heifers.

Scientists have offered several possible reasons why unsupplemented cows would have a biotin insufficiency and thus reduced hoof strength. First, unsupplemented rations are an uncertain source of this vitamin. Although biotin is present in many feedstuffs, scientists do not know how much of it is actually available to meet the cow's needs. There have been few studies in any species on the bioavailability of the biotin found in feedstuffs. In research with poultry, however, scientists have reported that less than half of the microbiologically determined biotin in feedstuffs is biologically available. It is also known that only   d-biotin is biologically active.

Second, high-concentrate rations may decrease biotin synthesis by microbes of the rumen. High proportions of readily fermentable sugars and starch in the ration produce acidic conditions in the rumen that result in imbalances among microbial species. Abel and Gomez (1997) reported that acidic rumen conditions reduced the microbial synthesis of biotin. This may help explain why higher-producing dairy cattle, which are more likely to receive high-concentrate rations, tend to have more hoof problems than other cows.

There is also a possible interrelationship between biotin status and laminitis, which has itself been connected with acidic rumen conditions. Laminitis is best known for the pain centered on the toe and lateral claw, but it also results in circulatory disturbances that can reduce the diffusion of blood and, thus, serum biotin to the horn-forming epidermal cell layer. Laminitis is a common denominator in sole ulcer, white line separation and heel erosion. Budras et al. (1996) noted that changes in hoof horn tissue structure during laminitis resemble those in biotin-deficient calves.

These possible causes of marginal biotin status are not, of course, mutually exclusive. Whatever the ultimate causes are, it is important to address them early. Because it takes so long for new hoof horn to fully replace weak or damaged tissue, dietary biotin supplementation to promote strong hooves should begin before problems develop.

Some studies have supplemented rations with 10 mg of biotin per head daily, but most have included 20 mg per head daily. It is recommended that heifers receive 10 to 20 mg of biotin per head daily, starting at 15 months of age as part of a heifer rearing program. It's recommended that cows receive 20 mg per head daily throughout lactation and 10 to 20 mg per head daily during the dry period.

The primary targets for dietary biotin supplementation are dairy herds with ongoing hoof problems and high producing cows fed high-grain rations. Bred replacements heifers should also be supplemented.

References:

• Abel, H., and C. Gomez, 1997, unpublished data; Inst. Agri. Nutr., GÖttingen, Germany.
• Bonomi, A., et al., 1996. Dairy cattle ration integration with rumen-protected biotin. Effects on production and reproductive efficiency. La Revista di Scienza dell'Alimenta. 25:49.
• Budras, K-D., et al., 1996. Rate of keratinization of the wall segment of the hoof and its relation to width and structure of the zona alba with respect to claw disease in cattle. Am. J. Vet. Res. 57:444.
• Campbell, J., et al., 1996. The effect of biotin on sand cracks in beef cattle.Proc. 9th Int. Symp. on Disorders of Ruminant Digit. Mitzpeh Rachel, Jerusalem.
• Distl, O., and S. Schmid. 1994. The influence of biotin supplementation on the conformation, hardness and health of claws of dairy cows. Tierärztliche Umschau. 49:581.
• Fritsche, A. 1990. Biotin verändert das Zytokeratinmuster von kultivierten Keratinozyten. DVM thesis, Faculty of Veterinary Medicine, University of Zürich.
• Hagemeister, H. 1996. Effects of a long-term biotin administration on claw health in dairy cows. Proc. 9th Int. Symp. on Disorders of Ruminant Digit. Mitzpeh Rachel, Jerusalem.
• Hochstetter, T., et al., 1996. Effects of biotin on horn quality of the bovine claw. Free Univ. Berlin. (Report).
• Lischer, C., et al., 1996. The effect of biotin in the treatment of uncomplicated claw lesions with exposed corium in dairy cows. Part II: The healing process in supplemented animals. Proc. 9th Int. Symp. on Disorders of Ruminant Digit. Mitzpeh Rachel, Jerusalem.
• Midla, L.T., et al., 1997. Supplemental dietary biotin for prevention of lesions associated with aseptic subclinical laminitis in first-lactation Holsteins. Am. J. Vet. Res. (submitted).
• Zenker, W., et al., 1995. Histological and physical assessment of poor hoof horn quality in Lipizzaner horses and a therapeutic trial with biotin and a placebo. Equine Vet. J. 27:183.

Plays a key role in the synthesis of glucose, protein and fatty acids. Biotin adequacy is essential for normal cell growth and differentiation, especially epithelial tissue. Recent research indicates that in dairy and beef cattle fed dietary supplemental biotin, hoof integrity was improved and the incidence of several common hoof disorders was reduced.

Although much of the recent research into biotin supplementation has concentrated on hoof health and integrity, studies have also reported increased milk production and improved reproductive performance in cows receiving dietary supplementation of this vitamin.

For example, Midla et al. (1997) reported that first-lactation heifers receiving 20 mg of biotin per head daily produced 692 lbs (2.7 percent) more milk over first lactation than unsupplemented heifers. Bonomi et al. (1996) reported that cows receiving 10 mg of biotin per head daily during the first 150 days of lactation produced 4.7 percent more milk than unsupplemented controls (Figure 5). Milk fat and milk protein levels were also increased. The increase in milk protein levels was significant for months three to five, while the other measures of production were significantly increased for all five months of the study.

Increased milk production and milk component yields, increased plasma glucose and decreased plasma acetate were consistent with the metabolic function of biotin as a cofactor in gluconeogenesis and fatty acid synthesis (Bonomi et al., 1996). These researchers suggest that the biotin status of higher-producing cows appears to be inadequate as judged by the immediate increase in milk yield in the study.

Bonomi et al. (1996) also reported that days open were reduced by 15 days in supplemented cows. Similarly, Hagemeister (1996) reported that days open were significantly reduced by 17 days in field work testing the effects of biotin on hoof disorders. These data indicate that dietary biotin requirements may be higher than previously presumed.