Does feeding affect Lameness?

A study of foot lameness in Taranaki showed that 65% of lameness is due to the movement of cows to the milking shed and another 10 % was due to individual cow variation. This leaves about 25% of variance unexplained and it is possible nutritional factors may have been responsible.

A study of foot lameness in Taranaki showed that 65% of lameness is due to the movement of cows to the milking shed and another 10 % was due to individual cow variation. This leaves about 25% of variance unexplained and it is possible nutritional factors may have been responsible.
Poor nutrition, in particular sub clinical acidosis, leading to laminitis results in a weakening of the hoof, making it more susceptible to injury.

Love your cows’ Rumens

Feed eaten by the cow has to be digested by “bugs” or microbes in the rumen. The microbes ferment forages and most other feeds producing proprionic and acetic acids, which are absorbed through the rumen wall. Plant protein is incorporated into microbial protein and then the microbes pass into the cow’s intestine to be digested there by the cow.
Keeping the rumen fermenting well is like making wine. The fermentation has to occur in a balanced and controlled way, otherwise it will result in incomplete fermentation and or toxins being produced.
Therefore we need to be careful what we feed the rumen microbes so we both enhance and don’t upset the fermentation process.

What is Laminitis?

Laminitis is inflammation of the soft tissue under the sole and wall of the hoof claw. This inflammation damages the join between the hoof and the tissue underneath and weakens the claw making it more susceptible to injury. It occurs when toxins are released into the blood stream commonly as a result of acidosis.
Acidosis occurs when the pH of the Rumen becomes acidic (below pH6). This is usually associated with excessive levels of readily fermentable carbohydrate (sugars and starch), which the microbes in the rumen are not able to convert into organic acids and lactic acid fermentation occurs instead. This may occur when cows are fed readily fermentable carbohydrate such as grain, kiwifruit and other high carbohydrate feeds, especially if these are introduced rapidly without giving time for the rumen microbes to adapt.
Silages contain significant levels of lactic acid and can contribute to rumen acidity.

Is it a problem in pasture fed NZ Dairy Cows?

It appears from some measurements that have been taken from cows on pasture diets that their rumen pH is dropping below 6 at times, particularly when they are on lush improved pastures. The source of the acid is the weak organic acids such as proprionic, butyric and acetic acid.

Preventing acidosis

The secretion of bicarbonate in saliva controls acidity in the rumen normally. When the cow swallows she takes bicarbonate into the rumen to buffer the pH that is to neutralize the acid. Normally a cow secretes 150 –250 ml of saliva/minute and to do this she needs to chew for 9-10 hours per day. If we increase the amount of chewing she does, particularly chewing of her cud, she will produce more saliva and therefore secrete more bicarbonate into the rumen to counter-act the acidity there.
Chewing is stimulated by fibre or what we call effective fibre. That is food particles that are more than 1.7cm long. When the pasture is lush there will be insufficient effective fibre to stimulate the required amount of chewing. This will happen at times on NZ spring and autumn pastures.
The best way to counter this is to introduce a small amount of fibre, ideally straw, but hay may be the best option available.
Adding a buffer will help. Sodium bicarbonate is often used but its activity is very short. Magnesium oxide is also a good buffer and lasts longer.

Another tool is to use Rumensin, which helps counter acidosis and now has been shown to have a significant effect on lameness overseas.

Other factors?

Protein: High levels of crude protein have been shown to increase lameness. In spring our pastures are very high in crude protein and this may well be a factor.

Biotin: Rumenal acidosis has been shown to affect the microbes in the rumen, which produce vitamins in particular biotin. There has been a lot of work in Australia showing that supplementing biotin reduced lameness on pasture fed cows, but unfortunately the cost of this may be too high to have appeal here.

Zinc: There is a considerable evidence to suggest that increasing the zinc level in the diet improves the hardness of the claw and reduces the chance of injury. The response to inorganic zinc salts has been variable due to interactions in the gut creating a variation in uptake. Complexed sources of zinc are less affected by dietary antagonists and therefore reduce the variability of uptake and have been shown to be effective in reducing lameness.

Other Trace Elements
Low selenium, copper, iodine and cobalt have all been shown to predispose to lameness so it is important to have an effective mineral management programme

By Chris Pyke,
Dairy Consultant
Intelact Nutrition