Pigs on Grassland: Animal Growth Rate, Tillage Work and Effects in the Following Winter Wheat Crop

Abstract

ABSTRACT A total of fifty-six growing pigs were studied on a second year clover/grassland. Three experiments with a 2 X 2 Latin square design were conducted with two levels of stocking rate (10 or 20 m2 pig−1 week−1) and low (L, 139 g kg−1 DM) or high (H, 197 g kg−1 DM) crude protein (CP) content in the supplemental feed in four 14-day periods in two successive years. After 8 weeks with pigs, this area and a control area were sown with winter wheat and harvested the following year. Growth rate and feed conversion ratio were better with feed H, whereas stocking rate had minor influence on pig performance. The deepest pig tillage work was achieved at high soil moisture contents independent of treatment. However, 10 m2 pig−1 week−1 gave deeper tillage work than 20 m2 pig−1 week−1 in dry conditions. Wheat grain yield was larger on 10 m2 pig−1 week−1 with a variation between years, whereas CP level did not affect yields or tillage work. Pig tillage was competitive with mechanical tillage when soil moisture or stocking rate was high, whereas dry conditions were favourable for the control area. Wheat grain yield and pig tillage work showed a significant correlation. A balance between imports of N in the feed and exports of N in pig gain and grain yield was achieved with the (20 m2 pig−1 week−1, L) treatment combination. Stocking rate should be determined in relation to soil moisture content, when using pigs as a tillage implement, influencing the choice of CP level in the feed to achieve an appropriate N-fertilization.