Effect of dry or temper rolling of high or low protein wheat and its impact on rumen parameters, growth performance, and liver abscesses of feedlot cattle

The objective of this study was to assess the impact of dry (DR) vs. temper rolled (TR) and low (13%, LP) vs. high protein (18%, HP) wheat grain on rumen parameters, liver abscess incidence, and growth performance of feedlot cattle. One hundred and sixty crossbred Angus steers (302 ± 34 kg; 24 ruminally cannulated) were used in a backgrounding (BG) to finishing (FN) feedlot trial. Steers were blocked by weight and randomly assigned to 16 pens. The cannulated steers (3 per pen) were housed within 8 of the pens that were equipped with a feed intake monitoring system. The BG diet consisted of 60% barley silage, 35% wheat grain, and 5% supplement, and the FN diet contained 10% barley silage, 85% wheat grain, and 5% supplement (DM basis). Transition (TN) diets increased the proportion of wheat grain in the total mixed ration by 12.5% weekly. Ruminal samples were collected in each phase and ruminal pH was measured using indwelling loggers. Steers experienced lower (P≤0.03) ruminal pH with HP-DR and LP-TR than HP-TR wheat during the TN. Tempering HP wheat reduced (P≤0.03) the generation of fine particles and bouts of low ruminal pH. Steers fed HP wheat had higher (P≤0.001) ruminal NH3 concentrations throughout the BG and TN phases. Ruminal NH3 concentrations were higher (P=0.01) during the FN phase for steers fed LP-DR compared to LP-TR wheat. The C2:C3 ratio for BG and FN steers was greater (P≤0.01) with HP wheat; with a reduction (P<0.001) in the C2:C3 ratio with TR wheat during FN. Steers fed LP-DR wheat during FN had the shortest (P<0.001) meal durations, and DMI was reduced (P=0.04) with HP wheat. Steers fed TR diets had slower (P=0.01) eating rates and consumed more (P=0.02) meals with shorter (P=0.03) intervals between meals. Greater (P=0.01) ADGs were exhibited by FN steers fed LP wheat. Liver abscesses were notably more (P