Digestibility and energy value of pea (Pisum sativum L.), faba bean (Vicia faba L.) and blue lupin (narrow-leaf) (Lupinus angustifolius) seeds in broilers

An experiment was carried out to determine the apparent metabolizable energy (AME) and coefficient of apparent ileal digestibility (CAID) of nutrients of two pea cultivars (Pisum sativum L. ʻSohviʼ and ʻKaritaʼ), two fava bean cultivars (Vicia Faba L. ʻKontuʼ and ʻUkkoʼ) and one blue (narrowleaf) lupin cultivar (Lupinus angustifolius ʻPershatsvetʼ) in 144 5-week-old broilers. The methods used were excreta collection and slaughter method. A total of six feeding treatments including the basal diet were tested. Pea, faba bean and lupin diets consisted of 500 g of basal diet with 500 g of legume grain per kg respectively. Chromium (Cr) mordant straw (1.7 g/kg each feed) was included in the diets as an indigestible marker and the diets were pelleted. The CAID of nutrients for the individual test legume seeds was calculated by the difference. Essential amino acid content was highest in faba beans, moderate in peas and lowest in lupin. The AME of pea cv. Karita (13.8 MJ/kg DM) was higher (P ≤ 0.05) than that of faba beans (≤ 12.4 MJ/kg DM), while AME of pea cv. Sohvi (12.2 MJ/kg DM) did not differ (P > 0.05) from that of faba beans. The AME (7.0 MJ/kg DM) and the CAID of dry matter, organic matter and ash of lupin were lower than in pea and faba bean (P ≤ 0.05). The CAID of lysine and methionine were higher (P ≤ 0.05) in peas (lysine ≥ 0.858, methionine ≥ 0.831) than in faba bean cv. Kontu (lysine = 0.869, methionine = 0.714). The CAID of lysine and methionine in lupin and faba bean cv. Ukko (lysine ≥ 0.891, methionine ≥ 0.791) did not differ (P > 0.05) from other legume varieties. The CAID of cystine was higher (P ≤ 0.05) in peas and lupin (≥0.671) than in faba beans (≤0.516). The CAID of threonine varied from 0.770 (faba bean cv. Kontu) to 0.852 (pea cv. Sohvi), but did not differ statistically among cultivars (P > 0.05). In conclusion, peas cv. Karita and cv. Sohvi were a good source of energy and amino acids and their amino acids were well digested except for cystine which was moderately digested in cv. Karita. Faba beans were a moderate source of energy and have a good digestibility of lysine, but digestibility of the most amino was found to be relatively low. Most amino acids, in particular lysine was well digested in blue lupin, but it was a poor source of AME. The poor energy value of blue lupin was related to its poor apparent ileal digestibility of dry and organic matter.