Farm trials confirm the benefits of feeding reduced levels of protein

United Feeds' Keith Agnew (right) and Clarence Calderwood (left) during a recent visit to the Dervock farm of David Millar (second left) and his father David
United Feeds' Keith Agnew (right) and Clarence Calderwood (left) during a recent visit to the Dervock farm of David Millar (second left) and his father David

OVER the past number of years, United Feeds has successfully pioneered the feeding of rations containing reduced levels of protein to dairy cows here in Northern Ireland.

This work has been undertaken with a number of milk producers in different parts of the province and has entailed the close co-operation of the farmers involved with United’s Dr Keith Agnew and his technical team.

“We have developed these feeding options across a wide range of management systems and have also taken account of the various forage types and concentrates offered to lactating cows on local farms,” Keith Agnew explained.

“In fact, we are now at the stage when we can make this new approach to dairy cow nutrition available to a much wide range of milk producers in Northern Ireland.”

The trials undertaken by United Feeds have been part of a wider research project involving herds in the USA and Canada. The work has been carried out on the basis of feeding these amended diets throughout the entire lactation. All the herds were fed a basal TMR, topped up with nuts fed in parlour or through out-of-parlour feeders.

The work has confirmed that it is possible to maintain, and in some cases increase, milk production on lower protein diets. Individual peak yields of cows tend to be a little lower but cows will have a much flatter milk production curve. Thus, they will produce significantly higher levels of milk during the mid and latter stages of their lactation than their counterparts receiving a standard ration.

There is also strong evidence to confirm that cows fed lower levels of protein demonstrate higher levels of fertility performance this can have a major impact on the overall profitability of the herd. And, of course, as the level of dietary protein is reduced so will be the amount of urea excreted. In essence we are striving to reduce dietary protein levels without impinging on milk output while, at the same time, improving other aspects of animal performance.

One of the producers involved in the trial work was David Millar, who farms with his father – also David – near Dervock in North Co Antrim. Their Derrykeighan herd of 115 cows is milked courtesy of two Lely robots.

“We are currently averaging 8,500 litres at 4.16% butterfat and 3.43% protein,” David explained.

“The herd is calving the year round with our daily output currently averaging 32 litres per cow.

“The cows get out to grass during the grazing season. Turnout last year was on May 21st. However, we feed the same ration throughout the entire winter feeding season.”

The Millars are committed to making the highest possible quality forages. Four cuts of grass silage were taken last year. Home grown wholeccrop wheat is also part of the forage mix offered to the cows during the winter months.

“We offer a ration of first cut grass silage, wholecrop and a blend through the feeder wagon, from October through to May,” David further explained.

“The TMR at the feed face has been formulated to give 28 litres of milk. We then top up to yield with nuts on an individual cow basis in the robots.”

In 2009, the Millar family committed to working with United Feeds on a lower protein feeding trial.

Keith Agnew, who was a recent visitor to Dervock, takes up the story: “The average total protein in the diets fed to dairy cows in Northern Ireland is in the region 17% and 18%. Research carried out in Europe and North America has indicated that these levels are excessive and that total dietary proteins in the region of 15% are much more in line with a cow’s requirement.”

He added: “We have known for years that feeding extra protein to lactating cows will not necessarily increase milk yields. In fact, when this approach is taken increased stress is put on the cow as she has to excrete the additional protein as urea. This, in turn, puts more pressure on her metabolic systems with the result that both potential milk output and fertility levels are reduced.

“The cows in the Derrykeighan herd are currently achieving total dry matter intakes of 25 kilos on a daily basis, 16 kilos of which is accounted for by forages.

“The easiest way to reduce overall protein levels in the overall diet fed to cows is to manipulate the formulation of the TMR. And, of course, by taking out protein, this leaves room for other ingredients. For example, we can increase total dietary energy levels. And we can also include new products, such as DEMP. This is an innovative microbial protein technology, from Alltech, which has been designed to provide a unique, high quality protein source that delivers the complete array of essential amino acids to the dairy cow.”

United Feeds’ Clarence Calderwood calls in with the Millar family on a regular basis. He accompanied Keith Agnew on his recent trip to Dervock.

“The starting point for any work on feeding reduced protein diets is an accurate assessment of the protein levels in the forages to be fed. This is something that we do with David as a matter of course,” Clarence explained.

“For example, analysis has confirmed that last year’s first cut has a protein level of 12.8%. Moreover, we now know that it is feasible to reduce overall dietary protein levels, when feeding a wide range of forages.”

But the proof of the pudding is in the eating. And David Millar is best placed to comment on the impact of the new feeding approach on his own cows.

“We have recorded sustained improvements in yield in the region of 1.0 to 1.5 litres per day,” he commented.

“Cows don’t peak to the same extent they might have done in the past. However, they milk much more consistently throughout their lactations. We have also noticed a significant improvement in fertility. The number of straws required per insemination has dropped noticeably.

“For example, we are now able to consistently get our highest yielding cows back in calf at around 100 days in milk. This would never have been the case in the past!”

Protein is a very expensive feed component. So does reducing its level in a dairy ration help milk producers reduce their input costs?

“Not necessarily when looked at on a straight cost per tonne of feed basis, but when the cost of the total diet and the savings from improved health and fertility are accounted for then feeding lower protein diets is a big winner,” concluded Keith Agnew.