Nutritional Factors

The role of nutrition in lameness has been investigated all over the world, but it is a clear fac­tor. Feeding diets resulting in a prolonged drop in rumen pH will result in a dramatic increase in lameness (Vermunt, 2004).

Nutrition

Nutrition is hugely important for a high yielding and healthy cow. Sudden changes of diet should be avoided (especially when rearing young), particularly diets that contain high concen­trate. A cow’s condition particularly at calving is important as overweight cows are prone to a loss of appetite so intake of fibre decreases, and the animal becomes susceptible to acidosis and laminitis. Dry cows should have a condition score of around 2.5- 3.0 and he maintained at this level until calving.

High energy rations are being fed to dairy cows more and more as they are required to produce higher yields. When this happens. not enough fibre is fed to the cow to promote proper chewing, saliva production and rumen function to maintain a rumen pH above 6.2. High fibre diets, e.g. silage and hay, stimulate rumination, increase saliva flow and neutralise the acid produced in the rumen.

Rumen acidosis

Sub-acute rumen acidosis plays an important role in the initiation of laminitis and subsequent lameness. Feeding of excessive grain, non structural carbohydrate or other feed that is rapidly fermented in the rumen, are common factors in the development of laminitis as they incite rumen acidosis. The risk of laminitis development is lower if the concentrate to forage ratio is kept around 60 / 40.

Laminitis predisposes lameness due to claw lesions including white line disease, sole ulcers and sole haemorrhages; a disturbed circulation precedes the development. Nutrition is therefore important in the aetiology of laminitis although it is multi-factorial (Vermunt, 2004). Dairy cattle that are fed high energy diets may under some circumstances slug-feed for various reasons. When they consume Large quantities of feed containing highly fermentable carbohydrates in a short period, they typically produce a lot of rumen acids, which can greatly reduce the rumen pH.

When the rumen pH drops to a certain level, it tends to kill off many of the rumen organisms and endotoxins are released, impacting on the blood vessels throughout the body, including the hoof area. This can cause vasoconstriction and vasodilation and, subsequently, damage to the blood vessels. This in turn leads to serious and painful conditions; the episode is often marked by a distinct ring on the hoof horn as growth is disrupted.

Prevention of acidosis is accomplished by managing the cows’ diet. Fibre-based diets with adequate roughage, feeding buffering compounds and providing facilities where cows can eat without being rushed and forced to gulp down their meals all help to minimise acidosis. This is especially important for the younger animals in a herd as they are usually low in the social order hierarchy and therefore have limited opportunities to eat.

Protein

Some researchers believe that feeding too much protein also plays a role in the development of laminitis, as protein products degraded in the rumen produce ammonia, but the extent of this is unconfirmed. Other sources say that sulphur-containing amino acids contribute to sulphur bonds that give horn tissue the strength and resilience necessary to minimise lameness. It is known that poor quality feed increases the risk of claw lesions, particularly white line and sole lesions, and diets with an overall crude protein content of above 18 percent should be avoided.

Fat

High rations of fat (over 4 percent) can lead to secondary acidosis and should be avoided. This is due to low fibre digestion because micro-organisms in the rumen become coated with fat.

Trace elements

Trace elements, particularly zinc, manganese, copper and cobalt are a key component of the nutrition programme formulated to minimise lameness. These improve a cow’s immune system, promote reproduction and tissue growth, improve energy utilisation, increase rumen fermentation and digestion and are good for bone development and strength. Stresses on a cow’s body, such as lameness, mastitis and pregnancy, increase the need for trace minerals. Ensuring the diet contains trace elements can improve hoof health and reduce lameness disorders.

Zinc in particular has a role in improving hoof condition, due to its healing effect, increased rate of epithelial tissue repair and improved cellular integrity. Zinc is also required for maturation of keratin in claw horn tissue. Manganese helps minimise feet problems by maintaining leg conformation through proper bone and collagen formation. Copper plays an important role in strengthening both the horn and connective tissue of the foot. Cobalt functions in the formation of vitamin B12 in the rumen.

Biotin

A ruminant is traditionally considered to be self sufficient in B vitamins, but recent studies have shown that supplementing high yielding cows with B vitamins can promote a range of performance benefits, including increased yields and reduced lameness. Feeding high concentrate diets can cause rumen acidosis and reduce the synthesis of biotin. The biotin level needs to be built up slowly after calving, but is said to reduce the number of cows requiring repeated treatment for lameness in the same digit, reduces the rate of sole ulcers and improves the healing rate of hoof lesions. Therefore, it could be said that diets that minimise rumen acidosis and its effects should be fed. (Blowey, 2005)

Toxicity and other factors

Acute illnesses can cause horn production to be slowed down or even halted temporarily, depending on the severity. Changes occur in the hoof wall, which make it much more prone to damage, thereby rendering these animals very susceptible to hoof problems.

Changes at calving

A comfortable, low stress environment is particularly critical during the transition period following parturition to promote a rapid increase in feed intake and to minimise the duration of negative energy balance. These cows are also at particularly high risk of hoof damage due to a disruption in horn formation during pregnancy. It is well documented that lameness is more common during the first few months after calving, the most common problems being sole haemorrhages and laminitis. The reason for this poor horn formation is unproven, but it means that the corium is very fragile and more susceptible to bruising. Other stresses are often placed on the cow at the same time, such as a change of diet to a very rich concentrate-based feed, and introduction to a new housing system, both of which can also give rise to hoof problems. It’s also common for these cows to be more susceptible to other infections such as mastitis, as the immune system is weakened in pregnancy and parturition.

Breeding and genetics

Farmers today generally want their cows to be bigger and to produce more milk. However, more importantly is that, combined with good milk production, cows are selected for conformation – particularly of the legs, the hooves and the heels. It is essential that we breed cows that have good claw shape and gait and are therefore less susceptible to hoof infections. We should particularly look for animals who do not have flat feet and walk more upright, those that are not prone to sole ulcers or have genetically weak hooves and those who are not susceptible to other infectious diseases.

Information kindly provided by Delaval UK