CHANGES OF THE QUALITY INCLUDING MYCOTOXI N PROBLEMS OF THE PRIMARY GROWTH OF A HAY MEADOW - ARRHENATHERION ELATIORIS

A delayed first cutting of hay meadows is a main characteristic of man y nature conservation and extensification programms. However, little i nformation is available on the nutritive value of extremely late cut f orage. Therefore an experiment on a species rich, unfertilized, wet ha y meadow was carried out over 4 years in order to study the dynamics o f the nutritive value. The primary growth was cut from May on in a 2 w eeks interval until October. The dry matter yield, the species composi tion, and the weather were followed throughout the season and the nutr itive value was characterized by determining the net energy value, the crude protein content, the intensity of fungi infection and the occur rence of mycotoxins in the forage. The results are summarized as follo ws: 1. The maximum dry matter yield was obtained in the second half of June. This is of importance if a nutrient depletion of the soil was t o be achieved. 2. End of June the net energy value of the fresh forage was 5 MJ (NEL) per kg dm and the crude protein content 7 %; this resu lted in a low protein-energy ratio of 15. The value of the conserved f orage of the same cut was even worse. 3. Considering the ADF and ADL c ontent of the forage and the possible occurrence of secondary plant pr oducts with antibiotic effects it is concluded that in vitro methods w ith rumen liquor or faeces suspension are superior to chemical methods to get a reasonable estimation of the energy value. 4. The intensity of fungi infection as measured by the Ergosterin content of the forage was much more influenced by the cutting time within years than by dif ferences between years. There was no correlation between the Ergosteri n content and the concentration of mycotoxins. 5. Deoxynilvalenol was never found in the forage whereas the concentration of Zearalenon and Ochratoxin A was dependend on the year and the season. Highest concent rations were always found in October.