35 Effect of feeding 60% dried corn distillers grains plus solubles or the equivalent sulfur on performance, hormone concentrations, and glutathione peroxidase activity in yearling Angus bulls

Abstract

Abstract The objectives were to investigate the effects of feeding 60% dried corn distillers grains plus solubles (DCD) or equivalent sulfur as calcium sulfate (CaSO4) on performance, hormone concentrations, and glutathione peroxidase (GPx) activity in yearling bulls. Thirty-six half-sibling Angus bulls [256 ± 8 d; initial BW = 320 ± 2 kg] were assigned one of three treatments: 1) corn-based diet containing 60% concentrate (CON; S = 0.18%; n = 12); 2) diet containing 60% DCD as a replacement for corn (DDGS; S = 0.53% DM; n = 12); 3) CON diet + equivalent sulfur of the DDGS diet added as CaSO4 (SULF; S = 0.51%; n = 12). Bulls were fed in Calan gates to target an average daily gain (ADG) of 1.6 kg/d. Data were analyzed as repeated measures using PROC MIXED in SAS. Blood and semen samples were collected on d 0, 56, and 112 then evaluated for concentrations of testosterone, thyroxine, triiodothyronine in serum, and GPx activity in seminal plasma. By design, no differences (P ³ 0.14) were observed among treatments for final BW, ADG or dry matter intake. However, DDGS tended (P = 0.07) to have reduced gain: feed when compared with CON, whereas SULF was intermediate. No differences (P ³ 0.13) were observed among treatments for serum concentrations of testosterone and thyroxine; however, DDGS had reduced (P = 0.009) triiodothyronine concentrations compared with CON and SULF. A treatment ′ d interaction (P = 0.03) was observed for seminal plasma GPx. On d 56, GPx activity was greater (P = 0.03) for DDGS compared with CON, whereas SULF was intermediate, but on d 112, DDGS had greater (P £ 0.02) GPx activity compared with CON and SULF. Therefore, alterations in triiodothyronine concentrations and GPx activity among treatments indicates that DDGS may influence characteristics of semen quality.