INFLUENCE OF VARIETY, NITROGEN FERTILIZATION, LOCATION AND YEAR OF GROWTH ON THE NUTRITIVE VALUE OF WHEAT AS DETERMINED BY RAT GROWTH
The influence of variety, nitrogen fertilization, location (Grey Wooded vs. Black soil) and year of growth on the nutritive value of wheat fed to weanling rats was studied. Methods of dietary supplementation were: (a) no protein or amino acid supplement; (b) 0.6 per cent L-lysine — HCl; (c) wheat gluten to raise the total protein to 20 per cent. A complete vitamin and mineral supplement was added to all diets.Food intake was not influenced by any of the variables. Weight gains for a 2-week period were higher for rats fed Thatcher than for those fed Kenhi wheat (independent of protein content). Location and year of growth also influenced rate of gain. When lysine supplement was added, rats fed fertilized grain grew more rapidly than those fed unfertilized grain. Efficiency of food utilization followed a similar pattern to rate of gain, but varietal differences were less evident.Fifty to eighty per cent of the variation obtained in rat gain was associated with the protein or lysine content of the wheat. An inverse correlation of 0.72 was obtained between the level of protein in the wheat and the percentage of lysine in the protein. As there were no interactions between variety and the other variables, a biological assay with rats could yield useful information on the feeding value of wheat varieties, over and above information obtained from chemical analyses.