Chemical, physical, and nutritional characteristics of different samples of wheat

Thirty-three samples of wheat (Triticum aestivum L.) were assessed on the basis of physical and chemical analysis, protein quality and quantity, and metabolizable energy. None of the values, or combination of values, from the physical and chemical analyses showed significant correlation with metabolizable energy values. Biological tests demonstrated variations in the nutritive quality of the protein in the different wheats. The diets in which the samples of wheat were incorporated were formulated to contain different levels of protein and different proportions of wheat protein and soybean protein to stress in a variety of ways the pattern of available amino acids provided by the wheat protein. A significant response was obtained from lysine supplementation to different cultivars of wheat. Nevertheless, lysine was not always the primary limiting amino acid for growth, despite a consistent improvement in feed efficiency from lysine supplementation. No consistent difference was found in the nutritional quality of protein from wheats containing different levels of protein. Further tests of protein digestibility and amino acid analyses of various cultivars of wheat may explain the varietal differences in biological response.