Toxic Effects of High Dietary Sulfur on Growth Performance of Feedlot Calves during the Early Growing Phase

Three levels of dietary sulfur (.17, .22, and pens (6 head/pen). Pens were 43 m with 22 m overhead .27%, DM basis) were evaluated in an 84-d growing trial shade. The trial was initiated July 24, 1996. Steers were involving 108 crossbred steer calves (215 kg). Calves were implanted with Synovex-S® (Fort Dodge Animal Health, Fort blocked by weight and randomly assigned within weight Dodge, IA) upon initiation of the trial and then again on d 56. blocks to 18 pen (6 steers/pen). The basal diet contained (DM Three levels of dietary sulfur (.17, .22, and .27%, DM basis) basis): 12% alfalfa hay, 8% sudangrass hay, 63% steam-rolled were evaluated in a randomized complete block design. wheat, 6% yellow grease, 8% cane molasses, and 3% Composition of experimental diets is shown in Table 1. Diets supplement. Dietary sulfur levels were achieved by were prepared at approximately weekly intervals and stored in supplementing the basal diet with 0, .20, or .40% ammonium plywood boxes located in front of each pen. Steers were sulfate. Daily weight gain averaged 1.54 kg/d and was not allowed ad libitum access to feed. Approximately 40% of daily affected by dietary sulfur level (P > .20). However, DM intake feed consumption was provided in the morning feeding and tended to increase (linear effect, P = .15), and feed efficiency 60% in the afternoon feeding. Estimates of steer performance decreased (linear effect, P < .05) with increasing dietary sulfur were based on pen means. Assuming the primary determinant level. Observed daily weight gain was 101, 97, and 98% of of energy gain is weight gain, energy gain (EG, Mcal/d) was expected, based on observed NE intake (quadratic effect, P < calculated by the equation: EG = (.0557BW )ADG (NRC, .05). We concluded that exceeding a dietary sulfur level of 1984). Maintenance energy expended (Mcal/d, EM) was .17% (DM basis) in growing diets for feedlot cattle may have calculated by the equation: EM = .077BW . The NE and NE detrimental effects on the partial efficiency of energy of the diets were obtained by means of the quadratic formula utilization for maintenance and/or growth. ( ) where a = -.41EM, b = .877EM + .41DMI +