8 December 2000

PRACTICALITIES MATTERTOOFORRIGHTRATION

Feeding cows well goes

beyond the ration that can

be all too easy to produce

with todays user-friendly

computer programs.

Jessica Buss reports

ASSESSING whether a ration meets all the necessary parameters to ensure a healthy cow and implementing it well are just as important as the ration produced by a computer model.

Velcourt farms director Richard Snow believes that the Cornell Net Carbohydrate and Protein System for rationing, developed in the US, is the best available.

He is responsible for rationing 2600 cows managed by the company and a further 1500 cows on units where he provides technical support. The 1400 cows on the Ilchester Estate in Dorset, where he is based, average 9600 litres, with the top herd he feeds averaging 11,500 litres.

Mr Snow has been using CNCPS to check rations for six years. But until a new version was launched this summer, it was designed to be used as a trouble-shooting tool rather than a rationing program.

"I used CNCPS alongside another rationing program and when I put in what we were feeding it said what the ration would do more accurately."

Over the past two years being able to analyse feeds, particularly forages, in the way the program needs has helped improve the programs accuracy.

"The lignin fractions cant be analysed here. But now we have a UK database of feeds and Central Labs in Oxford scan our silage samples and send the results to a lab in New York State for them to assess the fibre fractions."

The cost, at about £20, is similar to an ordinary UK silage analysis and it often takes less time to receive the results.

Being able to analyse UK feeds for CNCPS as is allowing the herds using it to benefit from the 21 years of development of the system. "Even UK-sourced and US soya can differ," he says.

He believes CNCPS is far ahead of UK rationing systems: "It has been well funded and the researchers at Cornell also act as farm nutrition consultants so have an understanding of practical constraints."

This shows through when rations are calculated. Actual cow intakes and performance are as predicted by the CNCPS ration program, providing feeds are correctly characterised and its correctly implemented by the person loading the mixer wagon, he says.

The dry matter intake prediction is within 5% of what cows are eating on the herds Mr Snow rations.

CNCPS version 4, launched this summer, is user-friendly and has made it possible for producers to design rations for their own cows. But Mr Snow warns that a basic understanding of energy and protein nutrition and how to manipulate them is vital before attempting to use it on farm.

Many checks

Once a ration has been produced there are many checks that must be made on the specification before it is fed. "It may produce 50 litres of milk when fed to cows, but you must ask if it has enough fibre."

Mr Snow begins with a check on whether the cow requirements are described accurately on the ration spec sheet. Then, whether DM intake predicted is likely to be accurate.

But it is also important to check that metabolisable energy and protein supply are suitable for a similar amount of milk and that effective nutrient detergent fibre, predicted ruminal pH, protein from bacteria and rumen amino-acid balance are all within the necessary parameters. When these are not within the desired limits, production or cow health may suffer, he adds.

RATION CHECKS

Daily

&#8226 Trough remains scored.

&#8226 Dry matter intakes.

&#8226 Milk yields.

&#8226 Adjust ration + or -5%.

Weekly

&#8226 Forage dry matters.

&#8226 Margins over concentrates.

&#8226 Body condition score.

&#8226 Rumen function and dung.

&#8226 Feed stocks.

Above: The CNCPS program is benefiting herds by allowing more accurate rationing. Inset top: Richard Snow with the Penn State separator – which helps check that rations arent too finely chopped.