Exploring the effects of transport duration on the fecal microbial communities of surplus dairy calves.

Transportation significantly affects the health and welfare of surplus dairy calves, largely due to the various stressors and pathogen exposures encountered during the process. Concurrently, an animal's microbiome is known to correlate with its health status, with stress-induced alterations in the microbiota potentially precipitating various diseases. This study aimed to compare the effects of transportation durations of 6, 12, or 16 h on the fecal microbiota in young surplus dairy calves. We used a randomized controlled design in which surplus dairy calves aged 1 to 19 d from 5 commercial dairy farms in Ontario were allocated into 1 of 3 transportation groups (6, 12, and 16 h of continuous transportation). Health assessments were conducted before, immediately after, and for 2 wk following transportation. Fecal samples were collected before, immediately after, and at 24 and 72 h after transportation and subjected to 16S rRNA sequencing. Alpha diversity metrics showed no significant differences between the 3 transportation groups at any of the sampling time points. Although ß diversity metrics revealed no clustering by transportation groups, they indicated significant differences across sampling time points within each group. The overall analysis revealed a total of 22 phyla and 353 genera, with Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, and Fusobacteria being the most abundant phyla. Bacteroides, Escherichia/Shigella, Lactobacillus, Collinsella, and Bifidobacterium were the most abundant genera. The reduction in Fusobacteria abundance before and after transport was significantly larger in the 16-h transportation group when compared with the 6-h transportation group. We also identified several genus-level and amplicon sequence variation-level taxa that displayed significant differences in their abundances across various transportation groups, observed at all sampling time points investigated. This research identifies microbiota changes due to varying transportation durations in surplus dairy calves, providing a broad understanding of the microbial shifts in surplus dairy calves after transportation across varying durations. Although these variations may not directly correlate with overall calf health or indicate dysbiosis, these results emphasize the importance of further investigating transportation practices to enhance calf health and well-being. Further studies are warranted to elucidate the relationship between microbiota and calf health.

Effect of time of sample collection after onset of diarrhea on fecal microbiota composition of calves.

BACKGROUND: The effect of time of sample collection after onset of diarrhea on the fecal microbiota composition of calves is unknown. OBJECTIVE: Compare the fecal microbiota of calves with diarrhea onset on the day of sampling (D <24h), and calves having had diarrhea for >24 to 48 hours (D 24-48h). ANIMALS: Thirty-one diarrheic calves (20 D <24h and 11 D 24-48h), 3 to 7 days of age. METHODS: Cross-sectional study. Diarrhea was defined as a calf with loose feces or watery feces. Assessment of the fecal microbiota was performed by sequencing of 16S ribosomal RNA gene amplicons. RESULTS: Richness and diversity were not statistically different between D <24h and D 24-48h (P > .05), but bacterial membership and structure differed significantly (AMOVA, P < .001 for both comparisons). Linear discriminant analysis effect size (LefSe) showed an enrichment of Faecalibacterium, Phocaeicola, Lachnospiracea, and Lactobacillus in the feces of D <24h calves, whereas Escherichia/Shigella, Ligilactobacillus, Clostridium_Sensu_Stricto, Clostridium_Incerta_Sedis, and Enterococcus were enriched in the D 24-48h calves. CONCLUSION AND CLINICAL IMPORTANCE: Rapid changes in fecal microbiota occur during the first 48 hours of diarrhea with an enrichment of lactic acid-producing bacteria in D <24h followed by an enrichment in Escherichia/Shigella and Clostridium spp. in D 24-48h. The time from diarrhea onset to sampling appears to affect the bacterial composition. Researchers should standardize times for fecal collection based on the time of diarrhea.

Assessing dairy calf response to long-distance transportation using conditioned place aversion.

Surplus neonatal dairy calves are routinely transported long distances from the dairy farm of birth to calf raisers. Most of the research assessing the effect of transportation on young calves has focused on physiology and health, without considering calf affective states. The aim of this study was to assess the affective response of young male dairy calves to transportation using conditioned place aversion (CPA) testing. Three bouts of transportation exposed dairy calves (n = 95) to transportation for 6 (n = 31), 12 (n = 32), or 16 h (n = 30). During transportation, the trailer interior was made visually distinct using blue horizontal (n = 2 groups) or red vertical (n = 1 group) stripes. Distinct color and pattern combinations were used to create a visual association with transportation. A subset of calves (6 h = 14; 12 h = 14; 16 h = 14) were selected for CPA testing if they were ≥7 and <28 d of age at the time of testing after transport. A group of sham calves that were not transported (n = 13) and were ≥7 and <28 d of age at the time of testing also were enrolled. Wall coverings with the same color and pattern of those in the trailer were fixed in individual sham calf stalls for 6 h on the morning of transportation. Before transportation, calves were placed in a 3-compartment test apparatus with neutral walls and were able to move about freely for 15 min to habituate them to the test apparatus. Calves were CPA tested on d 2 after transportation. During the posttest, calves were placed in the test apparatus with 3 compartments including a neutral center pen (center), blue horizontal stripe compartment (side), and red vertical stripe compartment (side) for 30 min; calves were able to move throughout the apparatus freely. Time spent in each compartment was recorded using continuous observation and analyzed as a percentage of total time in the apparatus. Calves spent less time in the compartment associated with transportation compared with the compartment with no prior association (22% vs. 42% ± 3% of time in the transportation-association and no-association compartments, respectively); however, this behavior was not affected by transportation treatment. Results from this study suggest that calves may perceive transportation to be aversive regardless of duration but may also be attracted to exploring a novel stimulus.

Calf Diarrhea Is Associated With a Shift From Obligated to Facultative Anaerobes and Expansion of Lactate-Producing Bacteria.

Diarrhea is the leading cause of morbidity, mortality and antimicrobial drug use in calves during the first month of age. Alteration in the bacterial communities of the gastrointestinal tract occurs during diarrhea. Diarrheic calves often develop anion gap (AG) acidosis associated with increased concentrations of unmeasured anions including D- and L-lactate. However, studies investigating the association between gut microbiota alterations and the development of acid-base disorders in diarrheic calves are lacking. We investigated the fecal bacterial alterations of calves with diarrhea and its association with changes in blood pH, and AG. Blood and fecal samples from healthy and diarrheic veal calves were taken 7 days after arrival to the farm. The fecal microbiota of healthy and diarrheic calves was assessed by sequencing of 16S ribosomal RNA gene amplicons. Blood gas analysis was completed using an i-Stat analyzer. In healthy calves, higher richness, evenness, and diversity were observed compared to diarrheic calves. Phocaeicola, Bacteroides, Prevotella, Faecalibacterium, Butyricicoccus, Ruminococcaceae and Lachnospiraceae were enriched in healthy compared with diarrheic calves. Enterococcus, Ligilactobacillus, Lactobacilus, Gallibacterium Streptococcus, and Escherichia/Shigella were enriched in diarrheic calves. In diarrheic calves, an increased abundance of lactate-producing bacteria including Lactobacillus, Streptococcus, Veillonella, Ligilactobacillus and Olsenella was detected. Diarrheic calves had a lower pH and bicarbonate concentration and a higher AG concentration than healthy calves. Together, these results indicate that calf diarrhea is associated with a shift from obligated to facultative anaerobes and expansion of lactate-producing bacteria which are related to acidemia, low bicarbonate and increase AG. Our results highlight the importance of the gastrointestinal microbiota on the clinicopathological changes observed in diarrheic calves.