The aim of this study was to compare the effect of controlled-release monensin on the automatic registered body condition score (BCS), and biomarkers registered using a fully automated inline analyzer, such as milk β-hydroxybutyrate (BHB), milk yield (MY) and milk lactate dehydrogenase (LDH).
Two experimental groups were formed: (1) monensin group (GK) supplemented with monensin (a monensin controlled release capsule (MCRC) of 32.4 g, n = 42) and (2) control group (GO) (capsule containing no monensin, n = 42). Treatment began 21 days before calving, and the experiment was finished one month after calving. In order to gather data about MY, BHB, and LDH, Herd Navigator a real-time analyzer (Lattec I/S, Hillerød, Denmark) was used together with a DeLaval milking robot (DeLaval Inc., Tumba, Sweden). BCS was measured using 3D BCS cameras (DeLaval, DeLaval International AB). All data were registered at one, 15 and 30 days after calving. The statistical analysis was performed using SPSS 26.0 (SPSS Inc., Chicago, USA) package. It was concluded that in the group of cows with monensin supplement (a monensin controlled release capsule of 32.4 g,), the body condition score was statistically significantly higher at the 15th (+0.24, p=0.003) and 30th (+0.52, p<0.001) days after calving, the productivity of cows in this group increased by 10.25% from the 1st to the 15th day and by 22.49% from the beginning of the experiment to the 30th day (p<0.001), lactate dehydrogenase activities at the 15th and 30th days after calving in this group were lower (p<0.001), and also in this group, the number of cows with a value of β-hydroxybutyrate of 0.06 mmol/L decreased from the beginning of the experiment to 30 days after calving by 4.70% (from 19.00% to 14.30%) compared with the control group.

Ruminal acidosis is frequent in cattle fattening systems associated with grain-rich fibre-poor diets. This study aimed to assess the prevalence of ruminal lesions compatible with ruminal acidosis intensive fattening farms and its risk factors on farm. Rumens of 218 out of 1960 bullocks from six farms were classified in slaughterhouses, and the management practices and the type of feed were compared. The prevalence of lesions compatible with ruminal acidosis was high (65%), where 47% and 18% of the animals had ruminal lesions compatible with subacute and acute disease, respectively. Prevalence of lesions differed significantly between the farms, with differences in the management and feeding practices. Ruminal lesions compatible with ruminal acidosis are prevalent in cattle fattening units in Portugal and husbandry and feeding practices are likely to have an impact.