Virginiamycin and monensin supplementation in high-concentrate dairy cow’s diets

Abstract

The objective of this study was to evaluate the performance, apparent digestibility of nutrients and ruminal fermentation parameters in diets of high concentration for dairy cows supplemented with virginiamycin or monensin. Five rumen-fistulated crossbred cows with 88 days of lactation, average daily milk yield of 26 kg, mean body weight of 550 kg at the beginning of the experiment in a 5 x 5 Latin square design, were used. Proportion of these additives: 300 mg/d VM (VM300); 300 mg/d MO (MO300); 300 mg/d MV and 300 mg/d OM (VM300 + MO300); 300 mg of VM and 150 mg of MO (VM300 + MO150); Control, without additives (C). There was no difference in DM and nutrient intake, except for starch intake which was higher in the control group when compared to the VM group and a trend towards higher starch intake in the VM300 + MO300 group as compared to the group VM300 + MO150. There was a difference in the apparent digestibility of crude protein, indicating superiority of the groups that used the association of MV and OM when compared to the group supplemented only with MV. Higher milk yield was observed in the control group and in the groups supplemented with MV and associated OM when compared to MV. Food efficiency data showed better values for the control groups and those that used the associated additives. NUP and ammonia nitrogen values were higher in diets that used associated MV and OM. There was a superiority of animals supplemented with MV and associated OM at doses of 300 and 150 mg/cow/d, respectively, in maintaining higher ruminal pH values when compared to the combination at 300 mg/cow/day of MV and MO. The similar behavior was observed for fecal pH. Higher total propionate, butyrate and AGV productions were observed in the control group when compared to the VM group.