Vicia sativa can be cut for fodder, grazed, fed as hay or ensiled. Its nutritive value for ruminants according to maturity stage and preservation method has been reviewed by Tisserand et al., 1989.
Fresh Vicia sativa at early flowering has a crude protein content of about 24% DM, and OM digestibility in sheep reaches 74%. Nutritive value decreases with maturity but digestibility remains relatively high (69%) at the mature seed stage (Tisserand et al., 1989).
The nutritive value of common vetch hay is higher than that of alfalfa and sainfoin at a similar vegetative stage. At the flowering stage, vetch hay is a valuable forage with an OM digestibility of 69% and a crude protein content close to 20% DM. Common vetch hay shows a progressive decrease of digestibility and degradability as its vegetative structures mature, unlike hairy vetch (Vicia villosa), which benefits from a compensatory effect produced by increasing grain proportions as the plant ages. The nutritive value at flowering was higher for Vicia sativa hay than for Vicia villosa hay, but the opposite was observed at maturity. Voluntary DM intake was not affected by the species or harvest stages (Haj Ayed et al., 2001). In sacco N degradability is quite high at flowering (78% effective degradability) and decreases with maturity (65% at seed filling) (Haj Ayed et al., 2001). At seed filling, the increased rumen bypass protein and lower ratio of "structural carbohydrates: non-fibre carbohydrates" indicates that Vicia sativa forage should be harvested at this stage (Caballero et al., 2001).
At the vegetative stage, the high concentration of tannic polyphenols in common vetch could be useful to decrease lipolysis and biohydrogenation of polyunsaturated fatty acids in the rumen and thus contribute to a higher transfer efficiency of polyunsaturated fatty acids to ruminant dairy products (Cabiddu et al., 2010).
In northern Ethiopia, vetch hay greatly improves the performance of goats browsing in semi-extensive conditions. It reduces unnecessary wandering during the dry season and makes better use of locally available browse resources. Supplementation with Vicia sativa hay up to 1.5% LW resulted in a gradual and almost linear increase in milk yield and lactation length, and in a decrease in milk fat and total solids percentages. Kid weight at birth, at 90 days and 270 days also increased significantly with this level of supplementation (Berhane et al., 2006a; Berhane et al., 2006b; Berhane et al., 2006c).
When Vicia sativa is harvested for ensiling, field wilting or a silage additive are required to prevent poor silage fermentation due to low contentrations of water-soluble carbohydrates and high buffering capacity. Silages of oat-legume and ryegrass-legume mixtures produce well-preserved silages, as the grasses contain more water-soluble carbohydrates and have low to medium buffering capacity (Kaiser et al., 2007).
A by-product of seed production, Vicia sativa straw has a nutritive value higher than that of cereal straws (barley, oat or wheat), with an OM digestibility of 53% and a crude protein content exceeding 6% DM. The energy value of common vetch straw is close of that of ammonia-treated cereal straws and the N value intermediate between that of untreated and ammonia-treated cereal straws (Tisserand et al., 1989). The evaluation of rumen degradation kinetics of legume straws confirmed their advantage relative to cereal straws, due to their higher DM degradability and degradation rate in the rumen (Bruno-Soares et al., 2000). The assessment of nutritive values of cereal and legume straws (including common vetch straws) based on chemical composition and in vitro digestibility showed that there were noticeable differences among species within each botanical family. Legume straws showed better nutritional quality than cereal straws, indicating that they could be considered promising and interesting sources of roughage for inclusion into ruminant diets (Lopez et al., 2005).
The use of Vicia sativa seeds in dairy rations has been subject to considerable research in the first decades of the twentieth century, due to contradictory results on their negative effect on milk production and on the taste and safety of milk and dairy products. It was notably suggested that the animals be gradually accustomed to vetch diets and that the adaptation of the cow be monitored by tasting the milk for the presence of the vetch flavour and bitterness. The milk may become bitter if dairy cows are fed 2 kg/day of Vicia sativa seeds, and the taste of vicine and convicine passes into the milk, which renders it unsuitable for both direct consumption and cheese production. Vetch-related problems of milk quality can be easily monitored by taste analysis and may be transitory in nature. The milk obtained from animals unaccustomed to feeding on diets containing Vicia sativa grain should be tested for the presence of vicine as well as ß-cyanoalanine and γ-glutamyl-ß-cyanoalanine and their metabolites. A maximum feeding rate of 3 kg/head/day is recommended (Enneking, 1995).
Milled Vicia sativa seeds (HCN 64.9 mg/kg) were found to be highly palatable during a three months feeding period with 3 adult Kumaoni bulls that had ad libitum access to wheat straw. Compared to the control diet (groundnut meal), lower red blood cell counts and haemoglobin levels were found during the feeding of Vicia sativa, but as the values were within the range reported for this breed, it was concluded that milled Vicia sativa seeds could be fed as a concentrate to non-lactating cattle (Pandey et al., 1960 cited by Enneking, 1995).