Nitrogen and phosphorus excretion on commercial rabbit farms: calculations based on the input-output balance.

Abstract

Manure is no longer exclusively considered as a fertiliser in areas with high densities of farm animals. Efforts are being made to reduce mineral excretion or to stimulate a more environmentalfriendly use. In such a context, both from the governmental side and for the producer, a reliable calculation of the on-farm production is very useful. Based on the balance between input (feed) - output (produced rabbits, dead rabbits), the nitrogen and phosphorus on farm excretion have been calculated for different production systems, production levels and slaughter weights. For a closed farm (breeding + fattening) the most convenient expression of mineral excretion is per female on average present on the farm. The excretion amounts to 7.42 kg N and 4.76 kg P2O5 per doe/year on a commercial rabbit farm based on an average production/doe of 45 fatteners of 2.5 kg. The excretion decreases from 76 to 61 g N and from 48 to 40 g P2O5 /kg rabbit produced with increasing productivity of the farm (35 vs 50 delivered fatteners/doe/year, respectively). In an exclusively fattening unit (between 0.8 and 2.5 kg weight and a feed conversion ratio of 3.40), the excretion amounts to 38 g N and 26 g P2O5, per kg rabbit produced.