Ensuring cows receive the correct balance of protein can improve health and help contain feed costs this winter.
David Wilde, ruminant product manager with Massey Feeds, predicts many farmers will face a challenging time getting cows settled on to winter diets this year, given the variable quality of grass silage.
“Lower energy levels and reduced intake potential will make it harder to formulate diets to drive production,” he says.
“It will be vital to do two things with diets this winter. The first is to watch what cows tell us about the diet, while the second is to ensure energy and protein are in balance.
“By monitoring intakes and performance, it is possible to determine how much energy (ME) is being consumed and the yield level this is supporting in practice, regardless of what the target yield was.
“The next and crucial stage is to assess the protein (MPE) supply to ensure there is not too much surplus protein in relation to the yield being achieved.
“MPE supply should be the same as the energy supply, or no more than two litres above it.
“If the potential yield from MPE is much more than two litres above the yield from ME, then cows will milk well initially, but will then try
and milk to the protein supply. This will result in stripping body condition, which can have significant consequences.”
Mr Wilde says the situation can be made worse with diets where excess protein is fed and an allowance for a body weight loss is included in the calculation of available energy.
He maintains this just accelerates the rate and impact of condition loss.
He says while losing condition is commonly understood to have a negative impact on fertility and lead to milk yields dropping and never fully recovering, new evidence suggests this will also be bad for foot health too - a view also supported by Owen Atkinson from Dairy Veterinary Consultancy.
Mr Atkinson says when cows lose condition, they mobilise fat from normal body stores and lose it from the digital cushion, which is an essential cushion of fat that sits just above the sole of the foot, starting near the heel and running forward to the toe.
He says the fat pad acts as a shock absorber and will not reach full effectiveness until the second or third lactation, putting heifers at particular risk.
Mr Atkinson says: “We now believe as cows lose body condition, so the fat pad cushion ‘deflates’, which then allows more opportunity for sole bruising and sole ulcers.
“The physical symptoms often occur a little later in lactation, although the damage will be done in early lactation as the imbalanced ration allows excessive body condition loss.
“Heifers have less of a fat pad to start with and are particularly prone to this problem.
“The loss of body condition in early lactation appears to be the trigger for fat pad reduction and subsequent lameness.
“It also sets off a vicious circle. Once a cow starts to go lame, she will have altered resting behaviour as it becomes painful to stand up.
“She will also eat less, meaning yield reductions and body condition loss continues, while fertility will continue to be compromised.”