VARIATION IN THE MINERAL-CONTENT OF CEREAL-GRAINS GROWN AT SELECTED LOCATIONS THROUGHOUT MANITOBA

Cultivars of wheat, barley, oats and rye were grown at 12 locations th roughout Manitoba over 2 consecutive years. The concentrations of macr ominerals Ca, P, Mg, K and S, and of microminerals Cu, Zn, Mn and Fe i n the grains were determined and found to differ (P < 0.05) among cult ivars of each grain. These differences among cultivars were considered to be minor, however, when comparisons between mineral concentrations and dietary requirements of economically important livestock were mad e. Location arid year of growth (environmental variance) were factors affecting the concentrations of Cu, Zn and Mn, accounting for 72-96% o f the total variance in these mineral concentrations (total variance = environmental variance plus cultivar x environmental variance). The c oncentrations of macrominerals in cultivars of wheat or barley differe d among locations and year of growth, with cultivar x environment effe cts accounting for 25-50% of the total variance observed, except for S where these effects accounted for 86-87% of the total variance; this percentage was lower for oats and rye where a lower number of cultivar s or locations was evaluated. Variation in mineral concentrations in t he four Manitoba-grown grains was often considerable with coefficients of variation ranging from 8.5 to 40.1%. With all cereal grains, suppl emental Ca, P, K, S, Cu, Zn, and Mn would be required to insure adequa te dietary intakes for ruminants in general and Mg for lactating dairy cows, with Ca, P, Zn and Fe required for swine and poultry, Mn requir ed for poultry and K required for some classes of poultry. Supplementa l Cu would be required with wheat-based diets fed to swine and poultry .