LAUSR

The aim of this research was to investigate the effect of drenching with a feed additive on rumination time (RT) and reticuloruminal pH post-partum at a Hungarian large-scale dairy farm. One hundred and sixty-one cows were fitted with a Ruminact© HR-Tag and from these 20 also received SmaXtec© ruminal boli approximately 5 days before calving. Drenching and control groups were established based on calving dates. Animals in the drenching group were dosed three times (Day 0/day of calving/, Day 1, and Day 2 after calving) using a feed additive containing calcium propionate, magnesium sulphate, yeast, potassium chloride and sodium chloride mixed in approximately 25 L of lukewarm water. RT before calving and sensitivity to subacute ruminal acidosis (SARA) were considered in the final analysis. There was a significant decrease in RT in the drenched groups compared to the controls after drenching. Reticuloruminal pH was significantly higher and time below reticuloruminal pH 5.8 remained significantly lower in SARA-tolerant drenched animals on the days of the first and the second drenchings. Drenching temporarily decreased RT in both drenched groups compared to controls. The feed additive had a positive effect on reticuloruminal pH and time below reticuloruminal pH 5.8 in tolerant drenched animals.