The effect of sulfur in cattle diets with varying cation-anion balances upon feedlot performance, blood chemistry and body fluid compartments.

Abstract

Corn distillers grains with solubles (DGS) is a major feed commodity ingredient used by the U.S. cattle feeding industry. Increasing dietary levels of DGS increases sulfur intake. Excess sulfur in finishing diets has been associated with reduced dry matter intake (DMI), body weight (BW) gain, and a negative dietary cation-anion difference (DCAD). The potential of supplemental cations to increase DCAD and improve performance of cattle consuming finishing diets containing MDGS was investigated. In a completely randomized block design, 186 crossbred steers (342 kg ±4.80) were blocked by weight, allotted to 28 pens, and assigned to one of seven treatments with 3 levels of wet, MDGS (25, 50, 75% of DM) supplemented or not with added cations. A Control diet contained no MDGS. Steers were fed to appetite twice daily (0800 and 1500 hr). On d 56, blood samples were collected prior to the morning feeding from each steer and analyzed for components. Steers were harvested at d 170 of the trial. Increasing DCAD with added cations reduced the metabolic acid load of steers as evidenced by reduced blood Cl and increased bicarbonate concentrations, but had no effect upon DMI, BW gain, or carcass characteristics. Steers fed MDGS did not differ compared with Control steers in ADG, DMI or G:F. Increasing the level of MDGS above 25% in diets resulted in a linear decrease in ADG, a quadratic decrease in DMI, and a trend towards a quadratic increase in F:G. Supplementation of finishing diets containing MDGS with sodium and potassium to increase DCAD is not an economical management tool to improve performance.