Effects of mineral supplementation on cattle performance when grazed mature wheat

Abstract

ABSTRACT This research paper addresses the hypothesis that mineral supplementation (sodium chloride and magnesium oxide at 1:1 weight ratio) for dairy heifers grazing mature wheat in the spring-summer period will improve live weight gain compared with the non-supplemented group. In addition, the potential of mineral supplementation to reduce environmental pollution through diluting urinary nitrogen content was evaluated in this study. The grazing study was conducted at the Dookie Campus, The University of Melbourne, Australia between September and November 2017. The study comprised two temporal trial replications with two dietary treatments; graze wheat with (supplemented, SUP) or without mineral supplementation (control, CTR). The first and second trial replications used 22 and 24 heifers, respectively to conduct a 22-day and 21-day weight gain measurement. Heifers in the CTR group had 11% lower daily water intake than those in the SUP group. No differences were observed in heifers’ weight gain and urinary nitrogen content and excretion. The study indicates that protein deficiency may override the mineral deficiency when heifer grazed mature wheat, and this may have led to no mineral supplementation effect on heifer performance. The level of protein in grazing wheat needs to be considered in feeding minerals to heifers.