When a lay person hears the word “certified” in connection with agriculture, he or she probably thinks of certified organic farming. At the same time, however, it is often forgotten that the farming and particularly the quality of the feed are analysed and monitored in very great detail. The specialist conference “A Radical Change in Feed Evaluation?” organised by the ETH Zurich Institute of Animal Sciences(1) recalled that feeding animals has a long scientific tradition and a large amount of data to fall back on.

To sum up the conference first of all: it did not mean re-evaluating every feed parameter. However, Michael Kreuzer, ETH Zurich Professor of Animal Nutrition, said in his introductory speech that he thought there was potential for an improvement in feed evaluation, and harmonisation between the various countries was desirable at the same time. For example he said there was a lack of agreement as to which energy should be examined. Should it be the energy that the animal digests from the food and converts, or the energy that is finally contained in the meat or milk? The ETH Zurich scientist could also see it was a hot topic from the lively interest – the conference scored a new record for the number of participants.

Carbohydrate is difficult to evaluate

Speakers assessed the current situation from various viewpoints in two sessions – the morning was devoted to ruminants and the afternoon to non-ruminants. Frigga Dohme from the Agroscope Liebefeld-Posieux Research Station presented developments in feed recommendations for ruminants in Switzerland. She said that feed evaluation as it exists in the relevant “Green Book” still retained its authority, but the assessment of the digestibility of the organic substance in silage maize needed revision. Karl-Heinz Südekum from the University of Bonn also acknowledged the need for revision. He said that carbohydrates in particular, which represent the majority of vegetable fodder, are insufficiently recorded in the feed evaluation. An improvement could be achieved by using enzymatic methods instead of the usual polarimetric determination methods.

Marc Boessiger from Agridea, the Swiss federal agricultural advisory centre in Lindau, appeared basically satisfied with the current situation. He drew attention to the fact that in relation to feed evaluation it must be remembered that fodder growing in Switzerland is intentionally operated at various intensities. Following the presentation by Peter Kunz from Bern University of Applied Sciences, some conference participants questioned whether the American CPM-Dairy milk feeding programme is suitable for extensive agriculture. The lecturer himself considers it to be a good programme since it enables the user to understand nutritional physiology better.

Their fodder has already been studied thoroughly but the questions are not all answered yet, for example how cows utilise grass. ((Photo: www.mcasutt.ch) large

Has the fat score fulfilled its duty?

The afternoon began with new recommendations not to the swine but to their feed. Marcus Rodehutscord from the University of Halle described the new evaluations now being carried out in Germany. For example the decisive factor for proteins and amino-acids is how much of them is digested before reaching the colon. ETH Zurich food scientist Martin Scheeder explained how pig feed affects human food. After looking back over the 20-year history of the fat score, he explained how this measure of fat quality was re-examined in more recent tests. These revealed that no differences in taste or production difficulties occurred in spite of relatively high fat scores. However, this may possibly also be a consequence of the fact that the fat score was used consistently in the past and has resulted in an increase in pig meat quality in Switzerland. In any case Scheeder concluded that the fat score describes the consistency of the fat to only a limited extent, but that near-infrared spectroscopy provides a method that allows a more discriminating assessment.

The conference closed with a talk by Paolo Colombani on the establishment of the “EuroFIR” European nutrient values data base (2), which also included a large poster presentation. The ETH Zurich food scientist drew attention to the fact that the documentation of the data is the core of a data base. He also said it was important to continue collecting high-quality scientific data. The fact that this is not always entirely easy for scientific reasons was apparent from a passing comment by Marcus Rodehutscord. In his opinion funding for the corresponding research was being cut to an increasing extent. Really astonishing, since it is ultimately all to do with our food.