NRC e INRA para raciones de caballos de ocio basadas en forrajes secos y concentrados granulados

Abstract

This work was aimed to find out the effect of the feeding system on the cost and nutritional characteristics of the diets used for non-grazing horses in different physiological or working conditions (pregnancy, lactation, growth and light exercise). Working with a minimum cost, linear programming software, limits of ingredients and nutrients for twenty four diets were set using, a) one of three fibrous feedstuffs (alfalfa hay, cereal straw and a 50:50 combination of them) as a fixed component, and fourteen other variable ingredients commonly used in Spain to formulate pelleted, concentrate compound feedstuffs for horses; b) energy and protein values of every ingredient calculated according to NRC (1989) and INRA (1990) horse feeding systems on the basis of a chemical composition of reference for each feedstuff; c) energy, protein and lysine requirements of the animals, also taken from both feeding systems, and d) limits applied to other nutrients and to the feedstuffs, based in published literature, which were the same whatever the system used to formulate the diets. A limit of voluntary intake was set for each type of animal according to values consistent with both feeding systems. Twenty three valid solutions were found, the lowest cost of them being those with cereal straw as the only permanent roughage. Differences between systems, of variable size according to physiological conditions, were found for the calculated intake of roughage, concentrate and total daily ration, and for the cost of the daily ration. Energy and starch contents of the rations were also different between systems mainly of those of lactating mares and of those with cereal straw. The excess of dietary protein over the protein requirements was always higher in the rations with alfalfa hay as the only roughage, independently of the feeding system used to formulate the diets.