Intake and Ruminal Fermentation Parameters of Beef Steers Consuming Bahiagrass Hay Treated with Calcium Oxide

To determine the effects of CaO treated bahiagrass hay on ruminal fermentation parameters of beef steers, 9 ruminally cannulated Angus crossbred steers (494 ± 145 kg BW) were used in a triplicated 3 × 3 Latin square design. In each of the 3 periods, steers were housed at the University of Florida Feed Efficiency Facility (3 steers/pen), where daily individual intake was recorded via the GrowSafe system. The steers had ad libitum access to bahiagrass hay, and were randomly assigned to 1 of 3 treatments: 1) untreated dry bahiagrass hay (n = 8; DH); 2) bahiagrass hay treated with 8.9% CaCO₃ (DM basis) + water (to 50% DM; n = 9; CC); or 3) bahiagrass hay treated with 5% CaO (DM basis) + water (to 50% DM; n = 8; CO). Starting at 0700 h (0 h), ruminal fluid was collected every 3 h for 24 h, and immediately after each collection, ruminal pH was measured. Ruminal fluid was analyzed for concentrations of VFA and NH₃-N. Data were analyzed as repeated measures using the MIXED procedure of SAS and the model included the fixed effects of treatment, time, treatment × time, square, and period. Animal within square and animal within treatment were included as random effects. Average DMI in kg/d (P = 0.76) and percent of BW (P = 0.67) were not affected by treatment. Ruminal concentrations of NH₃-N tended (P = 0.06) to be reduced in steers consuming CO. A treatment effect (P < 0.001) was observed for average ruminal pH, where steers consuming CO had the greatest pH when compared to DH and CC. No treatment effects (P > 0.05) were observed for molar proportions of acetate, propionate, or branched-chain VFA; however, butyrate molar proportion was lower (P = 0.002) in steers consuming CO and CC, when compared to DH. Moreover, no treatment effect (P = 0.64) was observed for acetate to propionate ratio; however, total VFA concentration was lower (P = 0.02) in steers consuming CO, when compared to DH and CC. Thus, we concluded that bahiagrass hay treated with CaO may reduce ruminal fermentation as indicated by decreased total VFA concentration without altering DMI.