Cattle are among a group we refer to as ‘cloven hoof animals’, which apart from cattle also include sheep, pigs, and goats.
A cloven hoof consists of two claw sections; one slightly larger than the other. The outer layer, which is the hard surface that makes contact with the ground, is called the horn of the hoof. This is made from a hard keratin substance not unlike a human fingernail, and is formed from the tissue directly beneath called the corium. A nutrient-rich tissue, the corium also contains a healthy blood flow. It produces new cells that are consistently pushed to the surface where they die and thus produce the hard layer that forms the hoof horn.
The new hoof material is grown out of the coronary band right where the hoof meets the skin – the new hoof material is soft and holds a higher level of moisture. Under the horn of the hoof, and between the horn and the corium, sits a softer keratin layer called the sole. As well as being softer than the horn, the sole is also more supple, and therefore acts as a cushioning material in the hoof. The white line, so often referred to in relation to hoof issues, is the line in which the hoof wall attaches to the sole. A healthy white line should be flexible and should allow the layers of the hoof ability to move as the animal moves around.
The bones within the hoof control the movement, and are protected within the hoof through the various layers that make up the cushioning of the hoof. This includes the digital cushion; a thick layer of fatty tissue that sits above the corium and the sole of the hoof. The entirety of the outlined areas of the hoof are richly supplied by blood vessels, and are constantly forming the proteins that are key to forming the different layers of the hoof including the hard keratin layers that add the outer protection.
The various hoof diseases that afflict cattle and ultimately progress to lameness can be the most serious single issue experienced on many farms.
Hoof diseases can take many forms; they can start with infections in the claw, infections on the outer skin that surround the hoof, or they may start in the laminar layers of the hoof itself. The issue will often start as a case of laminitis and then ultimately progress to white line disease, where the outer layer breaks away from the inner layer of the hoof.
When trying to identify the actual cause of hoof problems and lameness, the causes can be varied as the disease forms, and in so many cases the causes can be attributed to a multitude of issues. In order to successfully treat the problem it is important to correctly identify the type of hoof disease present, and treat it quickly before it progresses too far.
In order to identify and understand the differing forms of hoof disease that can afflict cattle, below we have outlined the variations and causes, as well as the symptoms that accompany these.
Symptoms: This disease is caused by a swelling of the laminar tissue which also cushions the pedal bone of the hoof. As the tissue swells, this interferes with the blood circulation that supplies the corium layer of the hoof. This in turn can cause tissue death, and the hoof can also grow in abnormal ways. Laminitis can cause a number of other complications, such as softening of the ligaments, compression of the digital cushion, haemorrhages in the sole as well as formation of low-quality hoof horn.
Ultimately severe laminitis can also lead to white line disease in which the white line is torn away from the sole of the hoof, allowing microbes and bacteria into the hoof.
Cause: It is accepted that the primary cause of laminitis is ruminal acidosis.
BOVINE DIGITAL DERMATITIS
Symptoms: Bovine Digital Dermatitis (BDD) is a recent disease, first seen in Italy in 2013. It is now prevalent in most countries and is thought to be now widespread in New Zealand. Research in 2016 found that BDD was prevalent on up to 80% of farms in the Taranaki region, and it is thought that it may be at similar levels in other regions too. Many farms show very mild cases, however if immunity is low in a herd it can become very serious very quickly. The disease normally presents as small warts on the heels, or on the fleshy area between the claws. At first the warts can look quite benign but under the right conditions they can quickly develop into inflamed red lesions that cause lameness and can even necessitate amputation of the claw.
They are caused by a class of bacteria called Treponema, which thrives in wet muddy conditions, and in animal manure. From there it quickly infects from hoof to hoof.
If identified and treated early it can be well controlled with antibiotics, foot baths, or topical sprays.
Cause: Research has shown that this disease can take hold in herds where immunity is low. The bacterial species involved usually start to take hold in the gut, and the endotoxins produced. Balanced mineral supplementation, particularly chelated forms of zinc when dosed in combination with sulphate forms, have been shown to reduce the disease incidence and the faecal bacteria shedding that produces it.
Symptoms: This disease is caused by a bacteria that gets into the hoof. This anaerobic bacterium thrives in muddy, wet conditions. If left untreated, the rot can lead to foul smelling pussy discharge. Normally a course of antibiotics is given. Prevention consists of avoiding hoof damage that allows the disease to enter the hoof – e.g. hard material on races and exit lanes. Also supplements such as chelated zinc and biotin supplemented into the diet have been proven to help harden the hoof. Other minerals such as copper and selenium are also important in respect of raising immunity within the herd to prevent the disease taking hold in the first place.
Cause: Sharp metal on races and exit lanes, soft hooves, low immunity.
DEVELOPING HARD HOOVES IN CATTLE
The first line of defence in combatting lameness is ensuring that cattle are fed correctly, and the diet is balanced in such a way that efficient rumination is guaranteed.
Acidosis is one of the largest issues when it comes to lameness on many dairy farms. Ruminal acidosis interferes with the nutrient supply needed for correct keratin formation within the hoof. Acidosis in ruminants causes excessive production of lactic acid, excessive production of histamine, as well as endotoxins. The inflammatory and toxic effects of this process interferes with blood supply and nutrient availability. It also sets up an inflammatory response in many areas of the body, including the hoof tissues negatively effecting healthy hoof horn production.
Factors such as modern grass cultivars with higher than normal soluble sugar content can lead to sub-acute ruminal acidosis, which over time detrimentally affects hoof health.
Better rumen performance and pH stability can be achieved by increasing the fibre content in the feed or feeding a rumen buffer. In order to effectively combat sub-acute rumen acidosis (SARA) it is important to feed a slow-release buffer.
There are a number of essential amino acids required for good hoof tissue production and final structure. The essentials include methionine, histadine, cysteine, and lysine. Research has shown that high producing dairy cattle struggle to produce adequate levels of metabolisable protein to meet production, let alone the demands of hoof growth. Supplementing rumen-protected forms of these amino acids can significantly improve hoof health and the quality of hoof horn produced.
In theory average grass-based diets are more than sufficient in protein, in fact some are too high in crude protein. Provided the rumen is working well, this crude protein is efficiently used by the rumen microbes, which are then digested to supply an efficient source of bypass protein which is absorbed further down the digestive tract. These proteins are then variously split and reformed into the essential amino acid that feed the body and build healthy hooves.
When this natural state is disrupted, it is often that the rumen is not working as efficiently as it should, and usually means that the rumen pH has moved out of its tight range of stability. At this point the cow is easy classed as suffering from sub-acute rumen acidosis (SARA) – or in the case of high grain feeding; lactic acidosis. When the rumen is functioning in this way the microbial levels drop, interfering with the production of bypass protein, and restricting supply of the key amino acids. With any form of acidosis, the make up of the microbial population changes to a bacterial type that is less efficient at utilising protein and starch, and instead of being a valuable feed source, produces toxins that cause inflammation throughout the body, including the hooves. This is why acidosis is so strongly related to lameness in cattle.
This vitamin is often not thought about when it comes to hoof health. However, we know that it is key to both calcium and phosphorous utilisation. It therefore becomes obvious that it is important in all types of keratin production.
This fat-soluble vitamin is a powerful cellular antioxidant, maintaining healthy membranes. This is particularly important in maintaining the health of the keratinised tissues of the hoof. Fortunately, green grass is a rich source of vitamin E, and trials here in New Zealand have shown no response to supplementation. However it is worth considering vitamin E can be low in hay and silages. The effects of sun on hay, and the fermentation of silages seriously degrades vitamin E. In situations where dry, or springer cows are fed mainly silages and hay for an extended period, they may still respond to a level of vitamin E supplementation.
This is probably the most recognised vitamin fed to dairy cattle in order to combat lameness. Used in the right situation it can be very effective, however it comes at a cost. Often we advise farmers to look at other key issues before introducing biotin, as it can be more economic to introduce management changes that will optimise natural biotin synthesis rather than just plugging the gap.
Biotin is probably the single most important vitamin in the keratinisation process, because it is a key co-factor in most of the enzymes involved in keratinisation, including amino acid metabolism, and cellular respiration related to hoof tissue.
Biotin is usually attached to the amino acid lysine – this combination is abundant in healthy plant material.
Once in the rumen, the biotin is then split away from the lysine through the action of a specific enzyme called biotinidase. The cleaved biotin is then efficiently digested in the upper part of the small intestine.
This works well provided the rumen is working efficiently. More often than not a biotin deficiency is simply being driven by inefficient rumination.
So in many cases, fix the rumen issues and you won’t need to supplement the biotin.
There has been a large amount of research on the use of zinc in hardening hooves; chelated forms of zinc are particularly effective. As well as hardening hooves, zinc is powerful in raising immunity to fight off infection.
Copper should always be dosed with zinc, because they work together in maintaining immunity. Copper also activates thiol oxidase, which helps in the formation of strong hoof horn.
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Kate Hepworth, Dr M Neary, Dr Simon Kenyon
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