Open access publications in the SLU publication database

Abstract

Keeping beef cattle outdoors during winter reduces costs and improves animal welfare, but increases
the risk of nitrogen (N) and phosphorus (P) runoff losses. This study evaluated a rotational
pen design on grassland with two groups of suckler cows given access to an expanding
staying area and a new feeding area each week (72 cattle ha−1), with one month’s stay per pen. The
spatial distribution of excreta and effects on N and P surface runoff was evaluated during six
months. The total excreta loads corresponded to 500 kg·N·ha−1 and 50 kg·P·ha−1. New feeding areas
did not distribute excretions evenly, which resulted in the highest proportion of excretions
(31%) occurring in the first week’s sub-area. The topsoil had significantly higher amounts of mineral-N,
mainly as NH4-N (29 - 81 kg·ha−1), than an unaffected area (13 kg·ha−1). Mean total runoff
losses were similar for both groups (1.4 kg·P·ha−1 and 9.0 kg·N·ha−1). Around 78% of N and 70% of
P runoff losses occurred during the month with cattle present. During the first two weeks with
heavy rain, N and P runoff losses were 50% higher from an area with suckler cows than a corresponding
vegetated sub-area without cows. The study design did not provide a sufficient distribution
of excretions and a high animal density in combination with trampling resulted in unacceptable
N and P run-off losses. An environmentally friendly design would need to include frequent
moving of all equipment and access to larger areas.