Biotechnologie, Agronomie, Société et Environnement (Jan 2005)
Improvement of lupin seed valorisation by the pig with the addition of alpha-galactosidase in the feed and the choice of a suited variety
Abstract
Three experiments were conducted to assess whether an a-galactosidase supplement improved the utilisation of lupin seeds by growing and finishing pigs and to determine the best lupin variety in presence of a-galactosidase. In experiment 1, three iso-nitrogen (iso-N) and iso-net energy (iso-NE) diets containing 15% of soybean meal (SBM diet) or 20% of lupin seeds (Lupinus albus var. Arès), with or without an a-galactosidase supplement (‘lupin’ and ‘lupin + a-gal’ diets, respectively), were ingested by 12 pigs fitted with a caecal canula, following a completely randomized experimental design. The ileal digestibility of a-galactosides tended to increase with the lupin + a-gal diet. Nitrogen retention of pigs eating the SBM diet was similar to that of those fed with the lupin + a-gal diet and higher than that observed for pigs given the lupin diet. The results suggested that a-galactosides are the main anti-nutritional factors in lupin seeds for pigs. The same diets were investigated in a production trial (experiment 2) involving 48 pigs with a live weight of between 30 and 105 kg. The fattening period was similar for the SBM and lupin + a-gal diets (107 d) and longer for the lupin diet (123 d). With the lupin diet there was a lower average daily gain (ADG, -16%) and a higher food conversion ratio (FCR, + 8%) than with the two other diets. The backfat of pigs fed with lupin-based diets contained fewer polyunsaturated fatty acids (PUFA) and had a lower w6/w3 ratio. In experiment 3, three iso-N and iso-NE diets containing different varieties of lupin (Lupinus albus cv Lublanc and Amiga; Lupinus angustifolius cv Boltensia) and an a-galactosidase supplement were investigated in 12 pigs fitted with a caecal canula, as in Exp. 1. The results showed that the digestible protein supply by the Boltensia diet was higher than in the others. However, the Boltensia variety led to a higher urinary N excretion than the Lublanc variety. The results obtained with Amiga were intermediate. Consequently, the utilisation of ingested and digested proteins was relatively high with the Lublanc diet, intermediate with the Amiga diet and low with the Boltensia diet. The results suggested that the Lublanc variety was better adapted for pig feed that contained an a-galactosidase supplement.
