Effects of essential oils and exogenous enzyme in feedlot finishing cattle diets high in flint corn ground at different particle sizes

Abstract Text: The objective of this study was to evaluate the interaction between two feed additives – MON (Sodium Monensin, Tortuga^®) vs. CRINA-RUM (the combination of essential oils - Crina^® Ruminants, DSM^® and α-amylase - Ronozyme^® RumiStar^TM) and two different ground flint corn particle sizes - ground corn (GC = 1.82 mm average particle size) vs. coarsely ground corn (CGC = 2.53 mm average particle size) on performance of finishing Nellore bulls. Two hundred fifty-six Nellore bulls (initial BW = 360 kg ± 38) were fed during 99 days with diets containing 82.5% ground corn (1.82 or 2.53 mm), 8.5% sugarcane bagasse, 5% soybean meal, 3% minerals-vitamins supplement and 1% urea. Animals were blocked based on initial BW and randomly allocated in 48 pens. Treatments were: GC + MON (1.82 mm ground corn and sodium monensin - 26 mg/kg DM), GC + CRINA-RUM (1.82 mm ground corn and the combination of essential oils - 90 mg/kg DM + α-amylase - 560 mg/ kg DM), CGC + MON (2.53 mm ground corn and sodium monensin - 26 mg/kg DM) and CGC + CRINA-RUM (2.53 mm ground corn and the combination of essential oils - 90 mg/kg DM + α-amylase - 560 mg/ kg DM). The data were analyzed using PROC MIXED of SAS in a 2 x 2 factorial arrangement (2 ground corn particle sizes and 2 feed additives). Pen was considered the experimental unit. No effect of treatment (P>0.05) was observed for final BW. Animals fed CGC (2.53-mm) showed a tendency to greater average daily gain (ADG; P=0.08) than animals fed GC (1.82 mm) – 1.60 and 1.50 kg, respectively. Effect of additive was also observed for DMI. Sodium Monensin (MON) decreased (P=0.013) DMI compared to the combination of essential oils and α-amylase (CRINA-RUM) – 8.70 and 9.34 kg respectively. No effects of treatment (P>0.05) were observed on feed efficiency (G:F) and dressing percentage. There was an interaction effect (P = 0.02) between ground corn particle size and feed additives for hot carcass weight (HCW). Animals fed CGC diets and CRINA-RUM presented 11.5 kg greater HCW (P<0.05) compared to animals fed CGC and MON - 295.2 and 283.7 kg, respectively. On the other hand, no effects (P>0.05) of additives were observed for HWC on GC diets. The CRINA-RUM combination for finishing cattle fed flint CGC diets increases HCW and can be an effective substitute for sodium monensin.

Keywords: beef, carcass, starch