The influence of processing upon the nutritive value of the potato. Digestibility studies with pigs

Digestibility trials were undertaken with pigs weighing 40 kg to determine the nutritive value of cooked potato flour, dried potato dice and raw potato mash. Apparent digestibility coefficients were, respectively, 0.96, 0.95 and 0.92 for energy and 0.89, 0.80 and 0.69 for nitrogen (N). The digestible energy values were 16.5, 16.3 and 15.7 MJ/kg d.m., and the contents of digestible N were 1.35, 1.05 and 1.02 g N/100 g d.m. When fed with balancer meals based on either maize or oat husk meal, the raw potato caused an apparent depression in the digestibility of N in the diet as a whole, and a reduction in the efficiency of utilisation of digested N. The findings are discussed in relation to the ability of the pigs to digest raw potato starch and the possibility of a component of raw potato, rendered ineffective by cooking but only partly so by drying, interfering with N digestibility and utilisation.