The use of peas and sweet lupin seeds alone or in association for fattening lambs: Effects on performance, blood parameters and meat quality

The aim of this study was to evaluate the effects of using sweet lupin and pea seeds singly or in association as protein sources in the diet of fattening lambs. We investigated lamb growth performances, carcass characteristics, blood parameters, chemical and physical characteristics of the meat and its fatty acid composition. Twenty-four "Gentile di Puglia" male lambs (body weight 15.8 ± 0.5 kg and age 38 ± 2 days) were divided into three homogeneous groups (n = 8) and fed for 7 weeks with three different experimental diets: L containing 250 g/kg diet (on as fed basis) of lupin seeds; P + L containing 150 g/kg diet of pea seeds plus 150 g/kg diet of lupin seeds; P containing 300 g/kg diet of pea seeds. Three types of pelleted total mixed rations were formulated to be isonitrogenous and isocaloric. Group P had a higher average daily feed intake than the other two groups, while there were no differences in slaughter body weights, average daily gains and feed conversion ratio due to dietary treatment. Carcass traits and tissue composition of leg were not affected by the protein source. Group L lambs had higher concentrations of urea than the other two groups at the end of the trial. Meat chemical composition, pH, colour and tenderness were not influenced by the protein source. Group L meat contained higher proportions of saturated fatty acids (SFA), in particular myristic acid (C14:0), than meat from groups P and P + L; comparison of unsaturated fatty acid (UFA) percentages also showed that lupin-fed lamb contained lower levels of oleic acid (C18:1n-9, cis-9) than the other two groups. Meat of lupin-fed lambs had a lower n-6/n-3 ratio than group P, but worse atherogenicity and thrombogenicity indices than groups P and P + L. In conclusion, when lupin was used alone in lamb feed, it had a negative effect on intramuscular fatty acid composition, while the use of pea and lupin together eliminated the negative effects of lupin.