PSIII-12 Dynamics of neonatal dairy calf behaviors and their association with early gut microbiota

Abstract The behavior of dairy cattle can be both an indicator and a determinant of their productivity and health. Additionally, animal behavior is also associated with their gastrointestinal microbiota through the bi-directional pathways of the gut-brain axis, influencing nutrient utilization and gut health. Few studies have looked at the dynamics of neonatal calf behaviors and their associations with early microbiota development. Therefore, the objective of this study is to observe feeding behaviors and activity of neonatal dairy calves and investigate its associations with the diversity and composition of early-stage gut microbiota. We used Holstein-Angus crossed calves (n = 25) raised in individual outdoor hutches and bucket-fed milk replacer twice daily. The number of milk exposures until calves were successfully bucket trained was recorded, along with milk consumption times during the AM feedings on d 7, 11, and 14. We also monitored the activity of the calves using HOBO Pendant G Data Logger accelerometers secured on the right hind leg of each calf to monitor standing and lying behavior from d 3 to d 13. Fecal samples were collected from the recto-anal junction of the calves at d 7 and 14 after birth and gut microbiota were analyzed using full-length 16S rRNA gene amplicon sequencing on an Oxford Nanopore sequencer. The Generalized Linear Model (GLM) was applied to evaluate effects of gender and birth weight on behavior and gut microbiota using RStudio 4.2.1. The Linear discriminant analysis Effect Size (LEfSe) was used to determine the unique bacterial species for each behavioral group. The results revealed that there was no influence of sex or birth weight on bucket training or consumption time; however, male calves exhibited significantly increased total standing time compared with female calves. We found no significant difference in microbiota between fast-learning calves (one milk exposure; n = 3) and slow-learning calves (5 or more exposures; n = 3). We observed greater alpha diversity of slow drinking calves (top 25%; n = 6) compared with fast drinking calves (top 25%; n = 6) on d 7 (Chao1; P = 0.03). The LEfSe analysis identified Akkermansia muciniphilia to be more abundant in fast drinking calves, and Megasphaera elsdenii to be more abundant in slow drinking calves. Additionally, a trend of differing microbiota composition was observed between the most active and least active calves (n = 4 per group) on d 14 (Bray-Curtis; P = 0.1), and many Prevotella species were more abundant in the most active calves. In conclusion, this study sheds light on the gut-brain axis of neonatal dairy calves at the species-level and provides further insights into cognitive, consumptive, and active behaviors.