The aim of this study was to evaluate different feed types collected from two districts (Ada’a and Adama zuria)
of two production systems (urban and peri-urban) based on season’s (dry and wet) in East Shoa Zone, for their
macro and micro mineral concentrations. Feeds in the selected districts comprised of roughages, concentrates, and non-conventional feeds. All feed samples were taken directly from the field supplied by the farmers. The feed samples were analyzed for the macro and micro minerals namely Ca, P, Mg, Cu, Fe, Zn, and Co, using atomic
absorption flame emission spectrometer and P concentration was measured by the spectrophotometer. The critical level (CL) used in this article is defined as the concentration of minerals below the level considering the requirements for dairy cows. The mean calcium concentrations in roughage varied from (0.13 to 0.55%); concentrate (0.14 to
0.64%) and non-conventional feed (0.34 to 0.69%) DM respectively. Out of the total feeds analyzed only, 26.92%,
66.15% for roughage (natural grass hay, sugar cane tops, and silage) and concentrates (noug seed cake, ground maize, cotton seed cake, and lean seed cake), respectively were found to be deficient in Ca. The mean phosphorus and
magnesium values were not deficient in analyzed feeds. The mean Copper concentrations varied in roughages (6.99 to 10.65 ppm); concentrate (6.67 to 8.78 ppm) and non-conventional (6.31 to 9.72 ppm) DM respectively. When those values are compared to the critical value (< 8ppm) of feeds analyzed only 19.23%, 79.92% and 65.22% for roughage (Triticum aestivum, Medicago sativa, Pennisetum purpureum), concentrates (wheat bran, wheat middlings, noug seed cake, cotton seed cake and concentrate mix) and non-conventional feeds (brewery by-products industrial, poultry liters) respectively were found to be deficient in Cu. The mean Iron concentrations varied in roughages (68.5 to 176.80 ppm); concentrate (73.94 to 174.81 ppm) and non-conventional (65.92 to 157.93 ppm) DM respectively.
When those values are compared to the critical value of (50 ppm) of feeds analyzed only 48.1% and 34.8% for
roughage (natural pasture, Pennisetum purpureum), sugar cane top) and non-conventional feeds (brewery by-products industrial), respectively were found to be deficient in Zn. The interaction effect of dairy feeds for most analyzed feed samples were significantly different (P < 0:05) for all Ca, P, Mg, Cu, Fe, and Zn within the study districts.
Similarly, the interaction effect between feed types and production systems were significantly different (P < 0:05) for Ca, P, Mg, Cu, and Zn but non-significant (P > 0:05) for Fe. Moreover, the interaction effect of feed based on sampling season was significantly different (P < 0:05) for Ca, P, Mg, and Zn but non-significant (P > 0:05) for Cu and Fe. Minerals such as Ca, Cu Zn and Co were present in inadequate amounts. Therefore, supplementation of these mineral elements is very likely to produce beneficial results in the ration of dairy. Hence, there is an urgent need for appropriate research to formulate area specific mineral mixture, and to devise supplementation packages for bio-available mineral salts.