02280naa a2200205 a 450000100080000000500110000800800410001902400540006010000180011424501250013226000090025752016460026665000150191265000230192765000150195065000140196565300160197965300150199577300640201015208182023-11-09       1977    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1016/0301-6226(77)90033-12DOI1 aORSKOV, E. R.  aNutritional principles and evaluation of by-products, waste products and new feeds for ruminants.h[electronic resource]  c1977  aAbstract: Evaluation of by- or waste products for ruminants is in principle no different from evaluation of other feedstuffs, but by-products may have some of the following disadvantages. They are often variable in composition, strictly seasonal and local in production, and often contain undesirable contaminants of organic or inorganic origin. The use of simple and inexpensive techniques to gain knowledge of suitability for animal feeds is discussed. For compounds high in nitrogen this involves an assessment of protein and non-protein nitrogen and the rate of rumen degradation of protein in order to assess whether the nitrogen would be mainly a source of nitrogen for rumen microbes or for additional host animal protein need. The evaluation of by-products as sources of energy can be made firstly by chemical analysis and secondly by determination of their rate and extent of rumen degradation. This can be determined by incubating the materials in nylon bags in the rumen. Animal experiments should include information on digestibility and voluntary food intake, and in order for an experiment to be meaningful, the materials studied should constitute the largest proportion of the diet. The type of animal and its level and type of production for which various sorts of by-product are most suited are discussed, together with their influence on rumen pH and type of fermentation in relation to possible associative effects when given together with other foods. Finally, various categories of by-product are discussed in relation to their protein: energy ratio and how they can form the most efficient combination with other foods.  aByproducts  aRuminant nutrition  aNutrição  aRuminante  aSub-produto  aUtilizacao  tLivestock Production Sciencegv. 4, n. 2, p. 165-175, 1977.