Dairy farmers facing up to Silage limitations

With higher milk prices and no substantial quota risk, dairy farmers are looking to boost output. National production figures, however, suggest cows are not generally milking as well as they could. According to NWF Technical Manager Tom Hough this is largely a legacy of the unusual forage growing season in 2007.
“My own experience is that while there are some herds that are milking very well indeed, there are others where performance is lower than expected,” Mr Hough explains.

He believes the biggest single reason for the range in performance is the difficult forage growing season last summer. The unprecedented wet season means that grass and maize silages are very variable.

“Those farmers who were able to cut early have made some good quality feed but quantity is a bit low. For the majority, clamps are filled with material that was cut late. The result is variable dry matter, high fibre silage, and it is proving a real challenge to get cows to produce milk off it.”

Faced with poorer than average silages and generally higher purchased feed costs, many farmers have sought to make the best of the mild autumn and have kept cows out longer. While this may have reduced short term costs, Mr Hough is concerned farmers have been storing up problems for the rest of the winter.

“Across the country we have seen mid and late lactation cows left out longer than usual to help eke out silage stocks. The problem is that while there may appear to be a good covering of grass, the dry matter was low and quality very variable. Together these add up to variable energy intakes and the consequence is that we were seeing cows in poor condition when they were actually housed.

“I suspect it will be well into January before cows which have only been yarded in the past few weeks settle down, for their condition to recover and for performance to improve.”

The problem then, Mr Hough believes is that the forages available are not ideal for driving high milk output.

Many grass silages are wetter with higher fibre levels than usual while energy levels are depressed. Conversely there are also some very dry silages which present different feeding challenges. Due to the variable forage quality, there is no obvious blue print to get cows firing this winter.

“High fibre levels in forages are restricting dry matter intakes,” Mr Hough observes. “Cows seem to be lazy this year due to the older, more mature grass silages taken later on in the season. With high NDF, low ME and long chop lengths, cows are spending too much time cudding and not getting much back in return.”

Mr Hough advises farmers to watch cows cudding as this can give an indication of the physical nature of the diet. Below 50 cuds per mouthful suggests the diet is short in fibre while a cudding rate of over 80 would indicate the diet is either too fibrous or that it is too acidic and that the cows is trying to produce more saliva to buffer the diet.

“In either case it will pay to get the diet sieved using a Penn State Separator and be prepared to change the physical composition. We have found in general that many sieved diets have too much material in the top, long material sieve and that intakes have been improved by adjusting the physical structure of the ration. In one herd just replacing long straw with chopped straw increased yield per cow by over 2 litres/day.

As well as high fibre levels, the acid nature of some of this year’s silage is reducing intakes, and where high intakes are being achieved we are seeing cases of high acid loading and SARA (Sub Acute Rumen Acidosis). Watch out for the classic signs of acidosis such as the presence of cud balls and drinking urine. Cows are responding to rock salt additions to feed faces and to the inclusion of rumen buffers.

Mr Hough also recommends farmers look at the sources of energy and protein being fed to ensure effective rumen synchrony. If silages are generally dull and lacklustre it is important to ensure rumen bugs are as effective as possible by providing them with what they are missing. If rumen energy is the issue he has been encouraging farmers to feed a higher level of starch and sugars from ingredients such as wheat, biscuit meal and molasses.

Where protein is the problem, the correct action will depend on the type of protein that is in short supply. Some rations are short of rumen protein so supplying correct levels of soya, rape or regulated release protein molasses products have shown good responses. If undegradable protein is the limiting factor then Sopralin is a good option. The key is understanding what your cows are telling you and adjusting rations safely and effectively.

“Although this year’s silage is far from ideal some farms are getting cows milking very well by paying close attention to the physical make-up of the diet and making sure the rumen bugs have the conditions they need. There is no reason why other herds should not follow suit now they are housed and there is more control over the diet,” Mr Hough concludes.