300 Effects of Associating Feed Additives on Rumen Ph Dynamics by Feedlot Cattle Fed a High-concentrate Diet

Abstract

Abstract Our objective was to evaluate the effects of feed additives on ruminal pH of finishing cattle fed a 90%-concentrate diet. Twenty four 18-mo Angus-Nellore crossbred bulls (IBW, 456 ± 6,5 kg) were allocated in a completely randomized design to three treatments with eight replicates each, as follows: 1) Control (MON) - Sodium Monensin (26 mg/kg DM, Rumensin, Elanco Animal Health); 2) Crina® RumistarTM (CR) - a blend of essential oils, 90 mg/kg DM + exogenous α-amylase, 560 mg/kg DM) and 3) CR + HyD® (25-hydroxy-vitamin-D3 at 1 mg/animal/d, CRD, DSM Nutritional Products). The ruminal pH and temperature was monitored individually for 98 days, using a wireless bolus, (SmaXtec Animal Care, Austria). Data were analyzed using the Mixed procedure of SAS and means comparison evaluated by Tukey test at P< 0.05. During adaptation period (i.e. first 14 days), bulls fed CR and CRD had increased rumen mean pH (6.40 and 6.36 vs. 6.16; P < 0.01) and minimum pH (5.89 and 5.87 vs. 5.57; P < 0.01) than bulls fed MON. In addition, rumen pH from bulls fed CR spent less time below 6.0 than bulls fed MON (256.07 vs. 452.62 min/d; P = 0.05). Regarding the total period, bulls fed MON had lower mean (6.22 vs. 6.51 and 6.42, P < 0.01) and minimum rumen pH (5.60 vs. 5.92 and 5.85, P < 0.01) than bulls fed CR and CRD. Additionally, feeding MON increased time duration of rumen pH (390.79 min/day, P < 0.01) and had a larger area below 6.0 (81.52 min x pH units/day; P < 0.01). Moreover, the addition of monensin increased pH time duration below 5.8 (161.10 vs. 121.13 and 122.56 min/day; P = 0.02) compared with CR and CRD, and increased ruminal temperature (39.60 vs. 39.51 and 39.5 °C; P < 0.01). We conclude that feeding Crina® RumistarTM and Crina® RumistarTM HyD® increased the rumen pH of bulls.