Performance, site preferences, foraging and excretory behaviour in relation to feed allowance of growing pigs on pasture

Foraging behaviour and daily weight gain (DWG) were studied in outdoor pigs given 100 or 80% of the indoor recommended feed allowance. In total, there were four groups of pigs, two per treatment. Each group consisted of 11 growing pigs with an initial live weight (LW) of 50.3 kg. The pigs foraged on a clover/grass pasture for 6 weeks in the cropping season. Behaviour was recorded within three zones of the experimental area: newly allotted area, transfer area and dwelling area. Mean DWG was 811 and 686 g on the 100 and 80% levels, respectively. The feed conversion ratio did not differ between treatments. A higher frequency of rooting and a lower frequency of behaviours categorised as other activities were observed on the 80% level than on the 100% level. Grazing and rooting were more frequent on newly allotted areas compared with the transfer and dwelling areas, whereas passive behaviour and other activities were more frequent in the transfer area. Defecation and urination were most frequent in newly allotted areas, followed by the dwelling area. The results suggest that successive allocation of new land gives rise to a distinct foraging area, which also is frequently used for excretory behaviour. Reducing feed allowance by 20% increased the nutrient intake from the herbage by ~5%.