Book of Abstracts
11th IFOAM Scientific Conference
11-15 August 1996, Copenhagen, Denmark
1Institute of Organic Agriculture, Faculty of Agriculture, D-53115 Bonn, Germany; 2Institute of Grassland and Environmental Research, Aberystwyth, Dyfed, SY23 4LL, Wales; 3Institute of Animal Hygiene, Faculty of Agriculture, D-53115 Bonn, Germany
Conversion from conventionel to organic agriculture is accompanied by changes in the feeding ration of dairy cows, leading among others to a restriction in the amount of concentrate and to an enhancement in the portion of legumes in the diet. As a result energy and crude protein supply can deviate widely from animal's requirements. Investigations were carried out in the winter and summer season to assess the effect of unbalanced diets on animal health. Biochemical and immunological blood parameters were used as indicators.In the first experiment (winter period) 40 cows were divided into two groups fed both a clover/grass silage-based diet, supplemented with 3 kg (DM) rolled faba beans from the 2nd to the 6th week after parturition. The control group was given additionally concentrate existing of 2.0 kg barley, 0.9 kg soya beans and 0.2 sugar pulp. Blood samples were drawn in the 2nd, 4th and 6th week after parturition. Results showed that the different diets had no significant effect on the milk yield. Neither the concentration of urea, aspartate aminotransferase, cholesterol, protein and immunoglobulin G in the plasma nor the number of leucocytes and the bactericidal activity in the whole blood were influenced by the diet within the experimental phase. In the second experiment (spring period) the effect of changing from indoor to outdoor conditions and changing from grass-based to clover-enriched swards was assessed refering to animal health parameters in a herd of 42 cows. While the concentration of urea, aspartate aminotransferase, glucose, cholesterol, total protein and immunoglobulin G in the plasma remained unchanged, bactericidal activity in the whole blood clearly increased when cows were put to pasture. In the following phase the herd was divided into two groups and put on clover-enriched resp. grass-based swards. Cows on the clover-enriched sward showed significantly higher urea levels in the plasma compared to cows on a grass-based sward whereas other biochemical parameters were not influenced. It could be concluded that a reduced amount of concentrate in early lactation as well as a high clover portion in the sward can be compensated by dairy cows without showing signs of health disorders.