Rumen fermentation shifts and microbial dynamics in mid-lactating Holstein dairy cows experiencing heat stress and subsequent recovery periods

Abstract

Objective In this study, we investigated the effects of heat stress (HS) on rumen fermentation, blood parameters, and ruminal microbial communities in mid-lactating Holstein dairy cows in Korea. Methods Our study involved 12 mid-lactation Holstein dairy cows aged 55.54 months with 2.5±0.65 parities and 100 to 200 days in milking (DIM), fed a total mixed ratio diet. Samples were collected during HS (temperature-humidity index [THI] = 81.69) and recovery (RC) period (THI 69.84). The samples were analyzed for rumen fermentation, blood parameters, heat shock proteins, and microbial communities in dairy cows. Results The milk yield, milk fat, milk protein, and milk urea nitrogen levels differed significantly between two-time points (p0.05). Blood total protein significantly increased during HS period compared with that during RC period (p0.8 (p<0.05) showed a complex structure with equal positive and negative connections, indicating Anaerohabdus furcosa and Ruminiclostridium cellobioparum as key species during the HS and RC periods respectively. Conclusion HS significantly impacts Holstein dairy cows’ physiological and metabolic processes, altering rumen fermentation, blood biochemistry, and gut microbiota during mid-lactation.

Keywords

• dairy cows
• heat stress (hs)
• microbiota
• mid-lactation
• recovery (rc)
• rumen