Posture and location preferences and gastrointestinal homeostasis in Holstein cows with tongue-rolling behavior

BACKGROUND: Tongue-rolling is the most common stereotypic behavior in dairy farming and is often considered an indicator of poor animal welfare. This study aimed to investigate the posture and location preferences of tongue-rolling cows and to compare digestion profiles between tongue-rolling and non-tongue-rolling cows. A total of 755 cows from four barns were selected for behavioral observation using scan sampling over a 7-day period to record the postures and locations associated with tongue-rolling. Subsequently, 10 tongue-rolling cows (TR group) and 10 non-tongue-rolling cows (CON group) were selected to analyze intake composition, apparent nutrient digestibility, rumen fermentation parameters and fecal microbiota. RESULTS: Results showed a 28.90% prevalence of tongue-rolling in the observed herd. Tongue-rolling was most frequently expressed in the stall area (40.59% in the morning, 41.99% in the afternoon) and a standing posture (82.80% in the morning, 89.28% in the afternoon). There was no significant difference in intake preference between TR and CON cows. Although ruminal pH was significantly lower in TR cows compared to CON cows (P < 0.05), other rumen fermentation parameters were not significantly affected. 16S rRNA sequencing results indicated that the fecal microbial composition was relatively similar between TR and CON cows; however, at the genus level, the abundances of norank_o_Bacteroidales (P = 0.045), Lachnospiraceae_NK4A136_group (P = 0.037), and norank_f_Erysipelatoclostridiaceae (P = 0.049) were significantly lower in TR cows than in CON cows, suggesting a potential dysbiosis that could affect gut barrier function. Compared with CON cows, TR cows exhibited significantly reduced digestibility of neutral detergent fiber and ether extract (P < 0.05). CONCLUSION: Overall, tongue-rolling behavior in dairy cows may be associated with altered nutrient utilization and subtle gut microbial shifts, highlighting its potential value as an indicator of compromised digestive efficiency and welfare status, and providing new insights into the understanding of this behavior.