Concentrations of Mo, Cu, Zn, Mn, Fe, N, Ca, P, Mg and K were determined in native and introduced grasses and legume forages from throughout northwestern Manitoba. Nutrient concentrations were compared with minimum requirements of cattle suggested by the Agricultural Research Council and the National Academy of Sciences–National Research Council. Differences in Mo concentrations were noted in forages between two geologic subareas within the study area. Cu and Mo concentrations suggested potentials for primary Cu deficiency in grasses throughout the region, and for Mo-induced Cu deficiency with grasses west of the Swan River formation and with legumes from all areas within the region. Throughout the study area, concentrations of Zn and Mn were found to be at deficient levels while those of Fe and Ca were found to be at adequate to excessive levels for cattel production. N and P concentrations in all forages were borderline to adequate, while Mg and K concentrations of grass forages were deficient to borderline with relation to the requirement of cattle.

-re, L. E. 1984. Geographical variation in the copper and molybdenum contents of forages grown in northwestern Manitoba. Can. J. Animal At the rate to two to three sites per township (93.24kmr) For personal use only.

BorLn, R. J., Dsvr-rx, T. J., Dnvsoer_e

No abstract

From two or three sites per township (93.24 km2), in the cattle-producing area of Northwestern Manitoba, 612 grass and 271 legume samples were collected and analyzed for zinc (Zn), manganese (Mn) and iron (Fe). Analyses were reported on an air-dry basis of approximately 90% dry matter. Within subregions, the mean Zn concentration ranged from 18.6 to 22.0 mg/kg and the mean Mn concentration ranged from 24.1 to 45.1 mg/kg for grass samples. The mean concentrations for the legume samples ranged from 17.8 to 25.5 mg/kg for Zn and 15.6 and 25.6 mg/kg for Mn. The mean Zn content in the legume samples was 3–5 mg/kg higher (P < 0.05) than that of the grass samples in three of seven subregions. In six of seven subregions the mean Mn content was 5–10 mg/kg higher (P < 0.05) in the grass than the legume samples. The range of Fe concentration was 31.3–1044.5 mg/kg for grass and 29.8–617.2 mg/kg for legume samples. Mean Fe for the entire study area was 107.6 and 93.6 mg/kg for grass and legume samples, respectively. For grazing cattle in Northwestern Manitoba, forages were deficient in Zn and Mn to varying degrees, with excessive intakes of Fe through soil contamination of forages possible. Recommendations for supplemental Zn and Mn should apply to the entire study area, and be based on the difference between the mineral content of forages and the requirement of cattle. Key words: Cattle, forage, minerals, zinc, manganese, iron