The use of faba bean and sweet lupin seeds in fattening lamb feed. 2. Effects on meat quality and fatty acid composition

This study aimed to evaluate the effects of using faba bean and lupin seeds used singly or in association as protein sources in the diet of fattening lambs. The physical and chemical characteristics of the meat and its fatty acid composition were investigated. Twenty-four “Gentile di Puglia” male lambs, weaned at 38 ± 2 days of age and at an average initial body weight of 15.8 ± 0.5 kg (mean ± sd), were divided into three homogeneous groups (n = 8) and fed for 8 weeks with three different experimental diets: FB containing 300 g/kg diet (on as fed basis) of faba bean seeds; FB + L containing 150 g/kg diet of faba bean seeds plus 150 g/kg diet of lupin seeds; L containing 250 g/kg diet of lupin seeds. Three types of pelleted total mixed rations were formulated to be isonitrogenous and isocaloric. Meat chemical composition, pH, colour and Warner-Bratzler Shear Force were not influenced by dietary treatment. Analysis of the intramuscular fat showed a higher percentage of the saturated fatty acid (SFA) myristic acid (C14:0) in the meat of L lambs than in FB and FB + L (7.13 vs 4.41–4.71%; P < 0.05); comparison of the polyunsaturated fatty acid (PUFA) percentages showed that the faba bean diet gave higher levels of linoleic acid (C18:2 n-6 cis9, cis12) than lupin (3.35 vs 2.44%; P < 0.05) and lower levels (0.31 vs 0.39%; P < 0.05) of linolenic acid (C18:3 n-3). The n-6/n3 ratio and the thrombogenicity index were not influenced by diet, whereas the atherogenicity index was lower, and therefore better, when lambs were fed the faba bean diet in comparison with the lupin diet (0.89 vs 1.29; P < 0.05). In general, for the parameters we studied, the use of lupin in association with faba gave intermediate values, without any significant differences compared to those for the protein sources used singly. In conclusion, the diet containing lupin had a negative effect on fatty acid composition of the intramuscular fat, while this effect was mitigated by the use of lupin + faba in association.