Abstract
The objective of this experiment was to determine the effects of 4 levels of trace mineral supplementation on feedlot cattle. Two hundred and forty Angus crossbred steers (n = 48, BW = 291 ± 27 kg) were stratified by arrival BW and source and randomly assigned to 1 of 4 experimental treatments in a randomized complete block design (12 pens/ treatment; 5 steers/pen). Cattle went through a 35 d depletion period prior to the administration of treatments where cattle received a supplement that included zero trace minerals and was formulated to meet or exceed other nutrient requirements not met by the ration. Cattle were administered treatments after transition to the finishing ration. The treatments included a negative control (CON) which contained no added trace minerals, a requirement treatment (1X) in which cattle received added trace minerals at requirement levels indicated by NASEM (Co 0.15 mg/kg, Cu 10 mg/kg, Fe 50 mg/kg, I 0.5 mg/kg, Mn 20 mg/kg, Se 0.1 mg/kg, Zn 30 mg/kg; NASEM 2016), a 2 times requirement levels (2X) treatment, and a treatment at four times requirement (4X) levels recommended by the NASEM. Iron was kept constant at 50 mg/kg for 1X, 2X, and 4X treatments. Due to feeding laws, Selenium was included at 0.1, 0.2, and 0.3 mg/kg for 1X, 2X, and 4X respectively. Treatment levels were chosen based on the 2015 Feedlot Consulting Nutritionist Survey. There was no difference in BW, ADG, overall DMI and G:F over the course of the experiment (Linear P ≥ 0.12; Quadratic P ≥ 0.17; CON vs Supplements P ≥ 0.47) There was no difference in marbling score, yield grade, back fat, REA, HCW, or dressing percentage between treatments (Linear P ≥ 0.23; Quadratic P ≥ 0.36; CON vs Supplements P ≥ 0.30). In conclusion, the lack of or addition of supplemented trace minerals at or above indicated requirement levels has no effect on cattle performance or carcass characteristics.
Trace mineral supplementation in feedlot cattle: implications for the inflammatory response, growth, and carcass characteristics
