THE poor performance of forage crops due to this year’s bad weather means winter diets for beef cattle need even more careful consideration than usual.
Debby Brown, vet and nutritionist, outlined some of the main feeding principles at a workshop in Barnard Castle.
The event was organised by EBLEX, as part of the Better Returns Programme.
She said the main aim when formulating cattle diets should be to ensure a healthy rumen.
Rumen bugs multiply best at a pH of 6.2-6.8. If the figure dips below six, growth rates and production will be adversely affected.
Digestion will virtually cease, resulting in lower feed intakes and reduced feed absorption.
However if the rumen pH is too low, it can lead to acidosis, she warned.
Mrs Brown said: “This should be avoided, at all costs, as it takes the rumen a long time to get back to normal, once acidosis has developed. In some cases, when it has been badly scarred, the rumen may never fully recover and the animal will not reach its potential.”
She said saliva plays an important role in rumen health.
“A healthy cow can produce up to 180 litres of saliva a day.
The liquid acts as a buffering agent, to keep the rumen pH as close to neutral as possible. Any sign of rejected cuds highlights a potential problem with the feeding regime,” said Mrs Brown.
“If you watch your cattle closely when they are lying down, you should see around 70 per cent chewing the cud. If only half of the animals are cudding at any one time, further investigation is needed.”
Achieving the correct balance of nutrients in cattle diets is a key element of ration formulation, she said. Sulphur is particularly crucial, as it is needed for many of the protein building blocks. Levels of sulphur in the soil have been depleted, as a result of efforts to reduce air pollution, so it can be lacking in forage. Cobalt is another essential dietary ingredient, as it is needed for the synthesis of vitamin B12.
Mrs Brown said it was advisable to monitor cattle dung, as the consistency will show up any dietary deficiencies. Loose dung can indicate insufficient fibre.
“If the dung is very loose, then rumen pH may be in decline.
Feed will be passing through the body too quickly, which means that some of its value is being lost. Stiff dung usually points to low rumen energy or protein supply. It may also be a sign that dry matter intakes are not achieving target levels.”
She said changes to the diet should be made slowly, as it takes around six weeks for the rumen to fully adjust to a new feedstuff. If a choice is available, then wheat straw should be the first option, as barley straw is more difficult to digest.