This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.
The effects of substituting 50% of dietary soybean with urea or a slow-release urea on finishing performance, meat quality, and digestion parameters of Nellore steers
The effects of substituting approximately 50% of the soybeans in the diet of finishing Nellore steers with either urea (U) and/or slow-release urea (SRU) on the steer performance and meat quality were assessed in two experiments. In the first experiment, 46 Nellore steers in a 104-day experiment (Exp. 1) were fed a control diet with U or SRU or U + SRU. In experiment 2 (Exp. 2), digestibility and microbial protein (MCP) synthesis were assessed in 4 steers by using a 4 x 4 Latin square design with 21-day periods. Four corn-based diets were used in both Exp. 1 and 2. 1) Control (CTL): 0% of non-protein nitrogen (NPN). 2) U: 1.66% of NPN. 3) SRU: 1.8% of NPN. 4) U+SRU: 1.72% of NPN. In Exp. 1, final body weight, average daily gain, dry matter intake, Gain: Feed ratio (G:F), carcass traits and steer meat quality were not influenced by the experimental diets. In Exp. 2, the apparent digestibility was similar for all diets, and the MCP synthesis was affected by dietary treatments (P = 0.065). The NPN treatments showed 25.5% more (P = 0.03) MCP efficiency (g microbial protein/kg of total digestible nutrient content consumed) than the CTL. We conclude that the partial replacement of SBM with U, SRU or U+SRU will provide similar animal performance without negatively impacting carcass and meat quality and improve the efficiency of microbial protein synthesis in Nellore cattle.
AN16609 Accepted 01 August 2017
© CSIRO 2017