Die Bodenkultur - Journal for Land Management, Food and Environment
A. Steinwidder und T. Guggenberger:
Investigations on feed intake and nutrient supply of dairy cows as well as nutrient balance studies on farms in grassland regions of Austria
In the present paper the results of an investigation on 30 dairy farms in mountainous grassland regions in Austria are presented. From these farms 11 were managed organically and 19 conventionally. Feed intake, milk yield and nutrient supply as well as nutrient excretion data concerning the dairy cows were collected. Due to the ecological principles on an agricultural farm, where nutrients are moving in a cycle between soil – plant – animal – soil, the N, P and K balances were calculated per farm and per area also.
The average forage intake was 14.9 and 13.8 kg DM and the milk yield was 16.5 and 19.4 kg on organic and conventional farms, respectively. The amount of concentrate differed significantly with 2.5 and 3.7 kg DM per day between the two farm management systems. The energy concentration of the ration was 6.1 and 6.3 MJ NEL kg DM-1 on organic and conventional farms respectively. A surplus of energy intake was measured in both cases.
The yearly N-, P- and K-excretion was on an average in both farm management systems 96, 14 and 159 kg cow-1, respectively. On farm basis the total amount of N, P and K was approximately at the same level on organic as well as on conventional farms. The calculated amount of available N (without unavoidable losses) was 78 kg in organic and 101 kg ha-1 grassland in conventional farms. The calculated amount of P was 16 and 25 kg and that of K was 176 and 215 kg ha-1 grassland on organic or conventional farms, respectively.
If the nutrient supplies per ha grassland are compared with the nutrient requirements – calculated on the basis of the codes of Good Agricultural Practice – a minimal deficit of N (about 15 % of requirements; -15 kg N ha-1) and a marked deficit of P (about 25 % of requirements; -7 kg P ha-1) were founad on an average of all investigated farms. These results did not differ significantly between organic and conventional farms.
Key words: dairy cows, feeding, nutrient excretion, organic farming, conventional farming.