Nutritional value of diets containing field bean (Vicia faba L.) seeds with high or low proanthocyanidin levels for pig

The nutritional value of pig diets containing about 30% field beans characterized by various levels of condensed tannins was studied. In a 54-day experiment on 24 Polish Large White x Duroc barrows (25-63 kg BW) four diets were fed: HT containing high-tannin field beans (cv. Nadwislanski), LT with low-tannin field beans (cv. Caspar), DHT with hulled high-tannin field beans, and DHTF with hulled high-tannin field beans and added white flowering pea hull fibre. The proanthocyanidin content of the HT, LT, DHT and DHTF diets was 591, 8, 70 and 70 mg/kg, respectively. Nutrient and energy digestibility, nitrogen balance, daily weight gain, and feed utilization were determined. The digestibility of N-free extractives and energy was significantly higher (P < 0.01), while that of crude protein was non significantly higher (P = 0.07) in the LT and DHT diets than in the HT diet. Daily nitrogen retention and utilization did not differ significantly among groups. Daily body weight gains (684-693 g) and feed conversion (3.02-3.07 kg/kg) also did not differ significantly among groups. Despite a slightly lower nutritional value as expressed by metabolizable energy and digestible protein, the HT diet that contained 0.1% phenols and 0.06% proanthocyanidins did not lower the growth rate of 25-63 kg pigs ( which gained slightly under 700 g daily) in comparison with animals fed the LT and DHT diets.