Methods for improving the nutritive value of fibrous feed: treatment and supplementation
Annales de Zootechnie
Once harvested and stored it is important to optimize the use of poor quality roughages (PQR) by ruminants. This can be done through treatments, that improve the quality of the roughage per se and through appropriate supplementation and feeding techniques, whether the PQR is treated or not. A tremendous amount of work has been done over the last twenty years at both research and development level. This paper recalls the basic principles and the main technologies available for optimizing the
... stive use of poor quality roughages. It also discusses and tries to highlight the advantages and drawbacks of transferring them in practice, with particular emphasis on urea treatment and multinutritional blocks. Two main steps should be considered: (a) feeding the microorganisms of the rumen in such a way that the growth and activity of cellulolytic strains are favoured. This is achieved either by a so called catalytic supplementation or by a treatment and (b) feeding the host animal the necessary nutrients that would ensure a satisfactory nutritional status (including its intake capacity which is generally low with such a type of basal diet) to meet its production requirements. Provided some key rules, described in the paper, are observed, the «urea treatment» is technically perfectly adapted to small production units, at both the individual and the cooperative level. Much practical field experience has been acquired now in an extremely wide range of agro-ecological and sociological conditions. Sealing is less a concern than with an anhydrous ammonia treatment and is not necessarily important when large quantities of plant material are treated (self covering). Locally available material such as banana leaves or sheaths, seko mats, banco, mud and old plastic bags proved to be successful on farm scale. Animal response to urea treatment is similar to that observed with anhydrous ammonia treatment achieved at the same alkali level. This response is optimum with moderatly yielding animals (whose diet consists essentially of PQR) making them the «target animals». The «catalytic» supplementation supplies Non Protein Nitrogen (NPN) (namely urea) and minerals (the "strategic" supplements). This supplementation hardly covers the maintenance requirements of the animals. The carrying medium is either liquid, such as the molasses-urea mixtures used in Egypt or solid, in the form of multi nutritional blocks, now used in villages in many countries. Practical examples are given. Thanks to these blocks it is possible to incorporate local agro-industrial by-products that, otherwise, would be under-utilized. The supplementation required for higher levels of production should, at any time: (a) not endanger the cellulolytic rumen ecosystem (this prerequisite is of particular importance with treated roughages for not losing the benefit of the treatment), by providing digestible matter of plant origin (b) supply high quality («by pass», PDIA or undegradable) proteins. Unlike commercial concentrates, it consists of: (a) farm residues such as haulms and leaves of pulse crops and vegetables, (b) legumes and other fodder trees, (c) byproducts of locally processed food and, to a lesser extent, cash crops such as brans and broken cereals (rice, etc.), cotton seed (lintless) and cakes, palm oil kernels, and (d) by-products of animal origin (fishing, slaughter house) and animal excreta (poultry litter). Work done in China on urea treatment/cotton seed cake supplementation is given as a practical example.