Nutrient composition of swill fed to peri-urban free-roaming pigs in Gert Sibande, South Africa

Pigs need a balanced diet for optimum physiology. We therefore investigated the nutritional composition of variably sourced swill fed to free-roaming pigs in Gert Sibande District Municipality, South Africa. Fourteen swill samples, originating from households, schools, restaurants, and wholesalers, were collected from pig producers in peri-urban areas. The samples were analysed for standard nutritional profiles, and mean outputs (descriptive and analytical statistics) were generated using the Statistical Package for Social Sciences. Overall, swill feeding strategies did not vary according to pigs’ age or physiological condition. The swill samples were high in moisture (household: 80.14%, school: 80.27%, restaurant: 54.36%, wholesaler: 56.63%), and low in dry matter (household: 19.86%, school: 19.73%, restaurant: 45.64%, wholesaler: 43.37%), compared to standard feeds. Excess crude protein and fibre contents and imbalanced macro-mineral compositions (calcium, phosphorus, and sodium contents) were observed. The moisture, dry matter, and crude fibre contents fell outside the recommended range. The crude protein, calcium, sodium, phosphorus, and ash contents were within the recommended range, but variances were wide, preventing standardisation. The significant variation in the composition of the swill samples has implications for pigs’ physiology, well-being, and general health. Swill feeding exposes pigs to vitamin and mineral deficiencies, hyperproteinaemia, increased vulnerability to infectious diseases, possible foreign bodies, and an inability to eat enough to meet the body’s nutritional requirements. Farmers should thus consider parboiling and dehydrating swill before feeding it to pigs as partial feed replacers, and pigs of ≤40 kg body mass should be fed a balanced ration, rather than swill. (Submitted 18 June 2024; Accepted 8 April 2025; Published 22 September 2025)