Buffer feed balance tricky
Buffer feed balance tricky
By Richard Allison
VARIABLE grass growth and lower milk prices are forcing many producers to reassess their summer feeding strategy, but feeding concentrates at grass remains a profitable option.
Many believe buffer feeding cows at grass is easy, says ADAS nutritionist Chris Savery. "But getting the balance right is difficult. Feeding too much depresses grass intake, while too little will leave cows short of energy leading to a drop in milk production and poorer fertility."
Which feeding strategy to adopt depends on herd performance. While lower yielding herds will fully exploit grazing, he believes herds yielding more than 8500 litres require a more cautious approach. Higher yielding cows are less able to cope with nutritional deficiencies and imbalances.
"When it is raining heavily, there is no point putting cows out to graze just because they were outside the day before. Keep them inside until the weather is more settled and grass growth rates have recovered."
Some producers in Northern Ireland have already brought cows back inside, says Sinclair Mayne, acting director of the Agricultural Research Institute of Northern Ireland. "Night frosts and wet ground conditions were holding back grass growth rates and making grazing difficult."
A summer feeding strategy must also aim to maintain fertility in spring calving herds, says Kite Consultings Norfolk based consultant Tanya Colman. "Sufficient energy is needed during this critical early lactation period to ensure good fertility. Producers cannot afford to have infertile animals.
"One concern in East Anglia is that some producers could be tempted to cut back on supplementary feeding to reduce costs, which may lead to lower conception rates."
But there is little evidence that buffer feeding helps improve conception rates, says Dr Mayne. "Data from 19 farms in Northern Ireland shows no reduction in conception rates to first service around turnout, rates being lowest in February." The hype over low fertility at grass is a myth, there is no evidence, he adds.
Once conditions improve, buffer feeding should be dropped as grass growth reaches peak, adds Dr Mayne. When cows need extra energy, provide compound feed, citrus pulp or maize gluten in the parlour instead. There is little benefit in offering forages unless grass supply has run short.
Parlour feeding also allows higher yielding cows to be targeted and levels can be quickly increased during periods of slower grass growth to avoid losses in milk production. "The problem with buffer feeding forages is that lower yielding cows, which do not require extra feed, compete with those which do."
Even with milk prices at 15p/litre, it is still profitable to feed concentrates to maximise milk production. Milk responses to concentrate feeding can be as high as 1.5 litres/kg concentrate in difficult grazing conditions, says Dr Mayne.
Another disadvantage with buffer feeding forages is the larger substitution rate compared with concentrates. "It is like eating a large bowl of All-Bran in the morning before breakfast, filling the rumen and restricting grass intakes. When grass supply runs short in June, then forages should be fed."
But which buffer feed do you use? Mr Savery advises producers to do their sums. Grass silage is not always the cheapest option on all units, particularly later cuts. "Consider concentrates as an alternative to forages, particularly with the difficulty of getting the right balance of buffer feeding."
The type of energy is also an important consideration, says Pye Farm Feeds director John Long. "Grass provides a continuous supply of energy to the rumen 24 hours a day and supplementary feeds must do the same to maintain rumen stability."
Any imbalance between energy sources will reduce rumen function. Using a feed containing a mixture of different starches and sugars instead of a single feed, such as barley or wheat, can increase milk yields up to three litres a day, he says.
But Dr Mayne is not convinced that additional sugar is needed with grazing. Grass already contains high levels of sugar and will remain high until later in the season. *
• Difficult to get right.
• Concentrates still profitable.
• Energy type important?