In recent years there has been a notable increase in outdoor pig production systems; however, the nutritional requirements of these animals have not been well established. To make nutritional decisions relating to the needs of grazing animals, accurate estimations of the herbage intake and value have to be made. N-alkanes found in the wax cuticle of plants have been used as markers to measure the intake of grass by grazing ruminants (Dove and Mayes, 1991). This experiment studied the use of the methodology in grazing pigs.

The intake and the digestibility of grass, and the effect of level of supplementary concentrate feed, were measured in late spring and late summer in two studies each with eight multiparous, pregnant sows. In the Spring study sows were nose rung to prevent rooting, but only unrung sows were available for the Summer study.