Chemical and physical characteristics of grains related to variability in energy and amino acid availability in pigs: a review

To optimise pig production, there is a need to define the variation in the available energy and amino acid content of feed grains and to understand th ose factors that influence nutritive value. Differences of up to 3.7 MJ/kg dry matter (DM) in digestible energy (DE) content were observed following a review of data for more than 70 cultivars of wheat. Similarly, analysis of data for more than 125 cultivars of barley revealed a range in DE estimate s from 11.7 to 16.0 MJ/kg DM. Differences of this magnitude are economicall y significant to pig producers. Cultivar has a minimal effect on the availa bility of energy and amino acids in cereals, although this variation is lar ger in legumes, particularly lupins. The cultural conditions and agronomic practices (e.g. fertiliser rate) have a greater influence on amino acid and energy availability than the growing region or the growing year. Many fact ors are shown to influence the availability of energy and amino acids in fe ed grains, including protein source and type, starch characteristics, fat s ource and type, non-starch polysaccharide components, and anti-nutritional factors. Although all of these factors can influence the nutritive value of a feed grain for pigs in some way, the availability of energy and amino ac ids will ultimately depend on the particular combination of these component s in a grain and how they behave in the presence of nutrients from other fe ed ingredients. For this reason, an understanding of the factors that influ ence the nutritive value of feed grains is more likely to eventuate when mu ltiple regressions of grain components are made against the availability of energy and amino acids.