Research on nutritional and metabolic factors that influence the production performance and health of cattle is highly important. This study investigated how different severity of ruminal pH drop influences lactation performance, energy balance, and blood metabolites in primiparous cows when these are fed a similar high-grain diet. Findings indicate that primiparous cows show individual differences in the severity of ruminal pH drop despite being fed the same high-grain diet. Results also revealed that cows with greater ruminal pH drop had greater feed intake, increased milk production, and improved energy balance at the start of lactation as well as greater blood cholesterol. Therefore, these cows seem to tolerate the drop of ruminal pH during early lactation, as long as the starch content in their diet dry matter is <25%. Likely, the individual differences in ruminal pH under the range reported in this study are well tolerated by primiparous cows.

Read the full article in the Journal of Animal Science.