Many crop cultures yield high amounts of by-products (straws from cereal grains and from legume pulses, staiks and stover from maize culture) that must be got rid of. Yet, they still contain nutrients which could be utilized in ruminant feeding. Because of their low digestibilities, these by-products are considered poor feeds. In many instances the nutritive value of poor feeds can be improved (by means of physical treatments, chemical treatments, association with other feeds in diets) and the by-products can be employed as ingredients in complete diets with results that, sometimes, are very good results.
The project intends to examine the following by-products:
- wheat straw (Italy, Portugal, Spain),
- maize stover (Spain),
- leaves and stubble residues from legume grain harvesting (Portugal).
Many crops produce large amounts of residues that have to be disposed of, such as straw from cereals and legume pulses and stalks and stover from maize. These residues contain nutrients which can be used in ruminant feeding but, because of their low digestibilities, they are considered to be poor feeds. In many instances, the nutritive value of poor feeds can be improved by means of physical and chemical treatments and then employed as ingredients in complete diets. The utilization of residues as feed is of particular importance in Mediterranean regions, where forage supplies are often limited. Research is being done to improve the digestibility of wheat straw in Italy, Spain and Portugal, maize stover in Spain and leaf and stubble residues from harvesting grain legumes in Portugal.
Straws and other fibrous byproducts which have been investigated untreated were confirmed as poor feeds compared with lucerne hay used as a reference. Their poor digestibilities were improved both by means of chemical treatments with alkali and by the correct association with other feeds and supplements in balanced complete diets. However, chemical treatments with ammonia from urea and with sodium hydroxide did not appear so useful on straws when these were included in complete balanced diets. The different nitrogen sources included in the diet of lambs did not affect their performances but the ratio of forage to concentrates did.
As far as wheat straw and maize stover are concerned, the possibility of improving their nutritive value by treating them with urea solutions will be studied as well. In all instances the by-products, either treated or not, either alone or in association, will be studied by means of in vivo and in vitro methods, which have been standardized at the international level. All this will provide useful information on how to use the above mentioned by-products in order to achieve the best results.
The social impact of the project conclusions on farmers could be very important in the Mediterranean environment.
28800 Alcala De Henares