Mineral profiles of agro-industrial by-products and locally available supplementary feeds and their implications for dairy cattle nutrition in Ethiopia

Abstract

This study assessed the macro- and trace mineral profiles of major agro-industrial byproducts (AIBPs) and locally available feed resources commonly used as supplementary feeds to dairy cattle in Ethiopia. A total of 58 samples belonging to five categories of supplementary  feeds (compound dairy rations/concentrates, oilseed cakes, wheat bran, middling and grains, brewery by-products, and pulse grain by- products) collected from different agro-industries and local sources were included in the study. The result showed considerable  differences in mineral concentrations both within and among the different categories of supplementary feeds suggesting the likelihood  of complementing a mineral or minerals deficient in some of the supplementary feeds/feed ingredients by using others. The concentration of most minerals measured in compound dairy rations lied within or above the ranges recommended in dairy cattle diets.  On the other hand, average mineral profile of the other supplementary feed ingredients revealed deficiencies of two or more of the  following elements: K, Mg, Na, P, S, Mn, and Zn for dairy cattle. Among the locally produced supplementary feed ingredients, oats grain  and the traditional liquor residue (`Areke attela`) had exceptionally high Ca content. Mineral elements variability noted in the different feed ingredients investigated in this study indicate the nutritional significance of combining various feed supplements in dairy ration  formulation in order to rectify deficiencies of different minerals. Moreover, there is a need to demonstrate the comparative advantages of compound dairy ration to the individual concentrate feed ingredients in terms of cost and supply of the nutrients required by dairy cattle  in order to promote its wider utilization in major dairy shed areas.