Feed efficiency of dairy cows fed amylase with monensin or a blend of essential oils

Abstract

Amylases and essential oils are additives of dairy cows that improve fermentation and ruminal health in dairy cows The objectives of this study were to evaluate the response of dairy cows to supplementation with an exogenous amylase in a basal diet containing monensin (MON) varying in ruminal acidogenic capacity, and to evaluate the substitution of monensin by a blend of essential oils (EO, Crina Ruminants, DSM) in a diet containing AM Thirty Holstein cows (207 ± 100 DIM) were individually fed a standard TMR for two weeks. At the end of the standardization period, cows were blocked based on parity and milk yield and were randomly allocated to one of three treatments in eight weeks of comparison period. Treatments were MON (M 15 mg/kg of DM), MON plus AMY (MA, 15 mg/kg of DM plus Ronozyme RumiStar, 375 KNU/kg of DM), and EO plus amylase (EA, 50 mg/kg of DM plus Ronozyme RumiStar, 375 KNU/kg of DM). Two diets were fed in sequence during the comparison period. A diet containing rehydrated and ensiled finely ground mature corn and finely ground mature corn was fed during weeks one to four (REC) and another diet formulated only with finely ground mature corn was fed during weeks five to eight (FGC). For all variables, two contrasts were tested: M vs. MA and MA vs. EA. Milk production and dry matter intake were not different between treatments. The substitution to MON by EO reduced milk fat yield (1.208 vs. 1.109 kg/d). Did not affect MUN in cows fed MA compared with M in REC diets (18.1 vs. 18.2 mg/dL), but decreased in FGC diets (20.3 vs. 22.6 mg/dL). The amylase supplementation tended to increased feed efficiency Milk/DMI and ECM/DMI when associated to M (1.59 vs. 1.55 and 1.59 vs. 1.51), however, the supplementation of amylase associated to EO decreased compared to MA (1.54 vs. 1.59 and 1.48 vs. 1.59). The treatment EA increased the proportion of butyrate in reticular fluid compared with MA (10.3 vs. 9.6 % of total VFA). When MA was fed in REC diets it did not affect rumen pH compared with M alone (6.53 vs. 6.49), and decreased in FGC diets (6.57 vs. 7.09).The amylase tended to increase the proportion of daily intake in the morning and to reduce the proportion of daily intake in the afternoon. Cows fed EA reduced chewing by 55 min/d compared with MA. The Addition of amylase increased feed efficiency in dairy cows only when fed with MON, the EO eliminated the positive effect of amylase.