Ingestion of earthworms, Pontoscolex corethrurus, by village pigs, Sus scrofa papuensis, in the highlands of Papua New Guinea

In a short (28-day) experiment, weanling village pigs, Sus scrofa papuensis, gained weight at the rate of 147 g daily when foraging on tethers in harvested sweet potato gardens, Impomoea batatas (L) Lam., and fed additional raw sweet potato tubers. A comparable group of pigs that had no access to soil lost weight and exhibited signs of protein malnourishment. The highly significant difference in growth rate was thought to be due to the foraging pigs consuming earthworms, Pontoscolex corethrurus, which were abundant in the soil.

Ten foraging pigs were closely observed over a period of 3 months. Daily weight gains increased to 190 g, and it was recorded that each pig ate between 414 and 1224 earthworms daily (half the daily amount being eaten in the first hour of foraging), and that this activity was predominant. As the day progressed, the pigs spent more time lying down, standing doing nothing, or eating green vegetation. These observations are discussed in the context of local pig husbandry.