NorFor vs NRC

NorFor predicts the protein value of feed rations much better than the official American feed evaluation system for cattle (NRC 2001). That is the conclusion from a comparison between the two feed evaluation systems that American scientist Glen Broderick (Wisconsin University) and Maria Åkerlind from Swedish Dairy Association have done.

They compared how accurate the two systems could predict milk yield and milk protein yield in dairy cows. Predicted yields from NRC and NorFor were compared with observed data from five American studies. The NorFor model performed substantially better, particularly in predicting milk protein yield.

- One main explanation for this is that NorFor calculates a variable efficiency for converting absorbed amino acids (AAT) into milk protein depending on how the feed ration is composed. NRC (2001) assumes a constant efficiency of 67 % conversion of AAT to milk protein, says Nicolaj Nielsen from AgroTech. Nicolaj is a member of the team that develops the model calculations in NorFor.

It is very important that a feed evaluation system can predict yields accurately. It will lead to a more precise feeding and reduced feed cost. Especially a good prediction of protein value can save expensive feed protein by avoiding unnecessary overfeeding.

Our developing group will continue to improve the protein evaluation of the system. We are working on how to include milk responses to different AAT-supplies and how to include recommendations for individual amino acids; methionine, lysine and histidine in the NorFor model. Hopefully it will bring us even closer to the optimal level of protein supply to dairy cows depending on costs for protein feedstuffs and on prices for milk, Nicolaj adds.

The correlation coefficient, R2 indicates the strength of a linear relationship between two variables where 1.0 is best.

Further information
Read the article (pdf)(Scroll to page 128 or use bookmark)

Watch a movie with Glen´s presentation (40min). The page is in Swedish. Scroll down and start the third movie on the right side, "Efficient protein feeding - how to use modern feed evaluation systems".

Contact us
If you are a Cattle Nutritionist, a cattle organisation, a veterinarian, a scientist, a farm consultant or anyone else with an interest in dairy cow and cattle feeding, don´t hesitate to contact us. It might be of mutual benefit.

Best regards
Patrik Nordgren, CEO