Natural vetch economic alternative to soybean meal in Tunisia

Resumo

The price of soybean meal as the main protein source for livestock is prohibitive in Tunisia. The potential to provide a cheap source of protein has long led to interest in vetch (Vicia ssp.) seeds for human and animal nutrition. The potential nutritional value of vetch seeds from eleven species and cultivars (Vicia amphycarpa, Vicia sativa, Vicia sativa 'Sanda', Vicia 'Y98', Vicia sativa 'Mghilla', Vicia villosa '2535', Vicia sativa 'INRAT303', Vicia villosa Sedjnen', Vicia narbonensis, Vicia sativa 'Languedoc' and Vicia villosa '3615') grown in the humid region of northern Tunisia were evaluated by chemical composition, in vitro gas production and in vitro digestibility techniques. The chemical composition of the cultivars of vetch seeds differed significantly (p<0.05). The content of organic matter ranged from 66.7 to 78.3% dry matter (DM). From among studied species and cultivars, Vicia villosa '3615' showed the best crude protein content (31.6% of dry matter) while Vicia sativa 'Languedoc' had the lowest content (25% DM). The organic matter digestibility ranged from 70.75% (Vicia sativa 'Languedoc') to 88.3% (Vicia sativa). The gas production after 96 h incubation in glass syringe, Metabolisable energy (ME) and short chain fatty acids (SCFA) were significantly different among the cultivars (P<0.05), with the highest value recorded for Vicia villosa '2565' and Vicia sativa and the lowest for Vicia villosa 'Sedjnen' seeds. The ME and SCFA were highest (P<0.05) in Vicia villosa '2565' and Vicia sativa. The result of this study indicates that such cultivars of vetch seeds have the potential to be used as feed supplements for ruminants.