Location: Livestock Nutrient Management ResearchTitle: Effects of wet distillers grains with solubles on visceral organ mass, trace mineral status, and polioencephalomalacia biomarkers by individually-fed cattle Author
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2014
Publication Date: 7/14/2014
Citation: Ponce, C., Brown, M.S., Osterstock, J.B., Cole, N.A., Lawrence, T.E., Soto-Navarro, S.A., MacDonald, J., Maxwell, C. 2014. Effects of wet distillers grains with solubles on visceral organ mass, trace mineral status, and polioencephalomalacia biomarkers by individually-fed cattle. Journal of Animal Science. 92:4034-4046. Interpretive Summary: Distillers grains are a co-product of the grain ethanol industry. Distillers grains can contain high concentratations of the mineral sulfur (S). In ruminant animal such as cattle, feeding diets that are high in dietary S concentrations can cause a neurological disorder called polioencephalomalacia (polio). In the first stomach compartment (the rumen) bacteria can convert dietary S to hydrogen sulfide. Hydrogen sulfide may be absorbed from the rumen, enter the blood stream and go to other organs where it can have a toxic effect. To evaluate the effects of dietary wet distillers grains (WDGS) on the risk of polio we individiually 24 steers (initial body weight [BW] = 850 lbs.) diets that contained 0, 30, or 60 % WDGS (DM basis). Steers were fed for 125, 150, 164 or 192 d (6 steers, 2/treatment) and were slaughtered when their backfat thickness was approximately 0.5 inches. Animal performance (daily gain, feed intake, feed conversion efficiency), weights of visceral organs, full and empty weights of gut segments, and samples of liver, lung, and brain tissue were obtained at slaughter. Tissues samples were analyzed for minerals and for enzymes involved with S and trace mineral metabolism. In general, feeding 30% WDGS did not have significant effects on animal performance or indicies of trace mineral and S metabolism; however feeding 60% WDGS decreased animal performance, increased gut fill, and altered copper status and several trace mineral enzymes. The results are interpreted to suggest that feeding 60% WDGS in steam-flaked corn based cattle finishing diets will increase the risk of trace mineral deficiencies and of polio in finishing beef cattle.
Technical Abstract: Distillers grains can contain high concentratations of sulfur (S). In ruminants, high dietary S concentrations can cause the neurological disorder polioencephalomalacia (polio). To evaluate the effects of dietary wet distillers grains (WDGS) on the risk of polio 24 steers (initial body weight [BW] = 385 kg) were blocked by BW and randomly assigned to three dietary treatments (0, 30, or 60 % wet distillers grains [WDGS] as DM basis). Steers were fed individually to determine the effect of WDGS on performance, visceral organ mass, trace mineral status, and polioencephalomalacia toxicosis. Steers were slaughtered at 125, 150, 164 and 192 d (2 blocks/slaughter) when fat thickness was approximately 1.3 cm based on visual appraisal. Weights of visceral organs, full and empty weight of gut segments, and samples of liver, lung, and brain tissue were obtained at slaughter. Tissues samples were analyzed for minerals and for enzyems involved with trace mineral metabolism. Steers fed 30 % WDGS had higher dry matter intake than steers fed 0 or 60 % WDGS (P < 0.05); and animals fed 60% WDGS had the lowest carcass-adjusted average daily gain (P < 0.09). However, WDGS concentration did not altered feed efficiency (P > 0.41) either on live or carcass-adjusted basis (P > 0.41). Steers fed 30% WDGS had greater liver S and Manganese concentrations and lower liver iron (Fe) concentrations than the control (P < 0.10; initial values used as a covariate). However, feeding 60% WDGS decreased liver copper (Cu) and increased liver Fe (P < 0.10) compared to steers fed 30% WDGS. Cytochrome c oxidase (COX) activity in brain tissue tended to decreased in cattle fed 60% WDGS compared to cattle fed 30% WDGS (P = 0.12), and COX activity decreased linearly (P = 0.06) in lung tissue as dietary WDGS concentration increased. Feeding WDGS increased gut fill in a linear manner (P = 0.01). Feeding 30% WDGS increased fractional mass (g/kg of EBW) of the small intestine (P < 0.10) compared to the control; whereas, feeding 60% WDGS increased fractional kidney mass (P < 0.10) compared to cattle fed 30% WDGS. Gut fill, Cu status, and COX activity may be compromised when WDGS are fed at high levels in diets based on steam-flaked corn.