Protein and amino acid digestibility and metabolizable energy value of pea (Pisum sativum), faba bean (Vicia faba) and lupin (Lupinus angustifolius) seeds for turkeys of different age

Apparent metabolizable energy (AME; by excreta collection) and ileal protein and amino acid digestibility (by a slaughter method) of peas (Pisum sativum ‘Karita’), faba bean (field bean; Vicia faba ‘Kontu’) and narrow-leafed lupin (blue lupin; Lupinus angustifolius ‘Pershatsvet’) seeds were assayed in 5- and 10-week-old turkeys. The highest AME values were observed in peas and faba beans, whereas in lupin seeds the AME values were lower, AMEN of the diets ranging from 9.58 MJ/kg in lupin diet (10 weeks) to 12.79 MJ/kg in pea diet (10 weeks). Bird age interacted with the feed effect, and AME of the pea diet increased with age of the turkeys, but in faba bean and lupin diets no age trend was detected. Coefficient of apparent ileal digestibility (CAID) of protein and amino acids was higher in the 5- than in the 10-week-old birds. CAIDs were highest in peas, moderate in lupin seeds and lowest in faba beans. CAID of protein, lysine and methionine ranged from 0.66 (faba bean, 10 weeks) to 0.83 (lupin, 5 weeks), from 0.79 (lupin, 10 weeks) to 0.92 (peas, 5 weeks) and from 0.59 (faba bean, 10 weeks) to 0.83 (peas, 5 weeks), respectively. In particular, CAID of cystine was considerably low in faba beans (0.35–0.47).