16 October 1998

Dietary changes can help stop lameness

Research has shown that

lameness can cost a 100-

cow dairy herd around

£12,000 a year in

treatment, lost performance

and replacements. While

creating the right

environment is important,

cow nutrition plays a critical

role in maintaining sound

feet. Jeremy Hunt reports

THE link between cow lameness and nutrition is far more complex than the simple assumption that laminitis is the problem and over-feeding of starch and protein-rich concentrates is the cause.

Reaseheath College dairy husbandry lecturer Tony Blackburn believes farmers can achieve big improvements in cow foot health by a greater awareness of cow nutrition throughout the whole of the production cycle, including the dry period.

"There is increasing evidence that incorrect nutrition during the dry period increases the risk of lameness after calving. Dry cows need to be inside for the last three to four weeks before calving to achieve total control of the diet," says Mr Blackburn.

Changes to dry cow diets in the 160-cow Reaseheath herd, along with improvements to the winter housing environment, have contributed to fewer lameness cases. Two years ago around 60 cases of lameness were being recorded annually; that has now been reduced to 15 per 100 cows.

"Straw is on offer ad-lib but only as a top-up. We dont make cows eat 5kg every day which is common practice in many herds. Three weeks pre-calving we feed 15kg a head a day of our 52% dry matter cow-mix – a 28% starch diet based on two-thirds maize silage, grass silage and whole-crop – to prepare the rumen and to meet the high-energy requirement of late pregnancy.

"Twenty years ago this level of starch in milking cow diets would never have been considered safe, but by blending it with forages in the diet and using mixer wagons its possible to feed it safely without posing a risk to health."

Mr Blackburn says there is a direct link between diet, which affects cudding rate, and in turn its ultimate impact on health problems such as laminitis.

"In many cases laminitis can be linked to dietary acidosis. When rumen conditions drop below a pH of six and some rumen bacteria are killed off, endotoxins are left and are absorbed through the rumen wall to affect the sensitive lamina.

"But for every trial that shows high-starch diets increase the risk of lameness I could find you plenty that say the opposite. The key is to get the rumen prepared before calving and not to get carried away with straw feeding during the dry period.

"Feeding 5kg a day of straw until calving and then suddenly expecting £50 PIN heifers, capable of 40-litre yields, to start taking 25kg a day of maize silage into the gut is asking for trouble," he warns.

Dietary needs

Mr Blackburn believes lameness can be reduced via nutrition only by carefully formulating the year-round dietary requirements of the cow, but he is concerned that most dairy farmers are unaware of the link.

He admits that up to two years ago cows at Reaseheath – based on standard rationing recommendations – were being underfed during the dry period.

"Recommendations are for a daily intake of 75-80 megajoules when they really need 110 megajoules. You ask a cow to eat 5kg of straw when her daily feed intake is barely 10kg of dry matter and you are heading for problems."

As well as tackling the nutrition of the herd, farmers concerned about widespread lameness should keep detailed records of all cases noting the type of lameness – sole ulcers, white-line disease – and when it most commonly occurs. Digital dermatitis, still the most widespread cause of lameness, is linked to physical conditions affecting the feet and not to diet.

Farmers determined to tackle lameness this winter – and cows being fed feeding high D-value, wet grass silage are most at risk – should take time to study the dietary constituents.

"Look at the risk factors for laminitis and evaluate how much starch is being fed. Look at protein in the feed; its as important to know what type of protein as well as how much. Those with wet, high D-value grass silage need to look at ways of drying it out. Straw is an option I am not too happy with; far better to consider incorporating some whole-crop silage if available.

"Consider the energy sources in the diet. If you are feeding maize silage it will provide slowly degraded starch so it needs to be countered with something with a rather faster rumen break down like sugar beet pulp or citrus pulp or even rolled wheat."

But endotoxins in the rumen, which can lead to lameness, can also be produced in the bloodstream following difficult calvings or an outbreak of mastitis.

"A cow with retained cleansings is far more likely to suffer subsequently from laminitis than she is to go lame through a dietary disorder.

"But it is all directly linked because if the cow is in the right condition when she calves and the calving is trouble-free, she is less at risk from secondary causes of lameness," he says.

COW FOOT CARE

&#8226 Nutrition awareness.

&#8226 Ration formulation.

&#8226 Dry cows at risk.