This study assessed the impact of dry (DR) vs. temper rolled (TR) and low (13%, LP) vs. high protein (18%, HP) wheat on ruminal fermentation, growth, and liver abscesses in feedlot cattle. Crossbred Angus steers (302 ± 34 kg; n=160; 24 ruminally cannulated) were used in a backgrounding (BG) to finishing (FN) trial. The BG diet consisted of 60% barley silage, 35% wheat, and 5% supplement, and the FN diet contained 10% barley silage, 85% wheat, and 5% supplement (DM basis). Four transition (TN) diets were used to adapt cattle to the FN diet. A numerical increase in large particles and reduction in small particles occurred when both HP and LP wheat were TR, with this response being greater for HP wheat. Steers experienced lower (P≤0.03) ruminal pH with HP-DR and LP-TR than HP-TR wheat during TN. Steers fed HP wheat BG diets tended to exhibit greater (P ≤ 0.09) G:F and NEg than steers fed LP wheat. Greater (P=0.01) ADG were exhibited by FN steers fed LP wheat. Liver abscesses were more (P<0.001) severe with HP wheat. While HP wheat improved the growth of BG cattle, it increased the severity of liver abscesses during FN.

The objective of this study was to assess the impact of low (13%, LP) or high protein (18%, HP) wheat grain subjected to dry (DR) vs temper rolling (TR) on growth performance, rumen parameters, and liver abscesses of feedlot steers. A backgrounding (BG) to finishing (FN) feedlot trial was performed using 160 302 ± 34 kg; 24 ruminally cannulated) Angus steers blocked by weight and randomly assigned to 16 pens. Cannulated steers (3 per pen) were housed within 8 pens equipped with a feed intake monitoring system. BG diets contained 35% wheat grain, 60% barley silage, and 5% supplement on a DM basis. Transition (TN) diets included sequential increases to the proportion of wheat grain in the total mixed ration to achieve a FN diet comprised of 85% wheat grain, 10% barley silage, and 5% supplement. Rumen pHs were measured with an indwelling logger and rumen samples were collected in each phase. Steers fed the HP-DR and LP-TR diets had lower (P≤0.03) ruminal pH than HP-TR during the TN phase. Tempering HP wheat reduced (P&lt;0.001) the generation of fine particles during rolling. During BG and TN, steers fed diets containing HP wheat had higher (P&lt;0.001) ruminal NH3 concentrations than the LP treatments. NH3 measurements during the FN phase were higher (P=0.01) for the LP-DR treatment compared to the LP-TR treatment. Greater (P≤0.01) C2:C3 ratios were noted for HP wheat diets during the BG and FN phases whereas the C2:C3 ratio was reduced (P&lt;0.001) with TR wheat during the FN phase. Greater (P= 0.01) NEgs were assessed for FN steers fed LP wheat. Steers fed HP wheat had more severe (P&lt;0.001) abscesses. Results suggest that HP wheat may limit the growth performance of FN cattle and increase the severity of liver abscesses.