Diet Influences Early Microbiota Development in Dairy Calves without Long-Term Impacts on Milk Production.

Gastrointestinal tract (GIT) microorganisms play important roles in the health of ruminant livestock and affect the production of agriculturally relevant products, including milk and meat. Despite this link, interventions to alter the adult microbiota to improve production have proven ineffective, as established microbial communities are resilient to change. In contrast, developing communities in young animals may be more easily altered but are less well studied. Here, we measured the GIT-associated microbiota of 45 Holstein dairy cows from 2 weeks to the first lactation cycle, using Illumina amplicon sequencing of bacterial (16S rRNA V4), archaeal (16S rRNA V6 to V8), and fungal (internal transcribed region 1 [ITS1]) communities. Fecal and ruminal microbiota of cows raised on calf starter grains and/or corn silage were correlated to lifetime growth as well as milk production during the first lactation cycle, in order to determine whether early-life diets have long-term impacts. Significant diet-associated differences in total microbial communities and specific taxa were observed by weaning (8 weeks), but all animals reached an adult-like composition between weaning and 1 year. While some calf-diet-driven differences were apparent in the microbiota of adult cows, these dissimilarities did not correlate with animal growth or milk production. This finding suggests that initial microbial community establishment is affected by early-life diet but postweaning factors have a greater influence on adult communities and production outcomes.IMPORTANCE The gut microbiota is essential for the survival of many organisms, including ruminants that rely on microorganisms for nutrient acquisition from dietary inputs for the production of products such as milk and meat. While alteration of the adult ruminant microbiota to improve production is possible, changes are often unstable and fail to persist. In contrast, the early-life microbiota may be more amenable to sustained modification. However, few studies have determined the impact of early-life interventions on downstream production. Here, we investigated the impact of agriculturally relevant calf diets, including calf starter and corn silage, on gut microbial communities, growth, and production through the first lactation cycle. Thus, this work serves to further our understanding of early-life microbiota acquisition, as well as informing future practices in livestock management.

Dill-McFarland KA ，Weimer PJ ，Breaker JD ，Suen G ... -  《-》

Bacterial communities in the rumen and feces of lactating Holstein dairy cows are not affected when fed reduced-fat dried distillers' grains with solubles.

Reduced-fat dried distillers' grains with solubles (RF-DDGSs) are co-products of ethanol production and contain less fat than traditional distillers' grains. The fat in corn is ~91% unsaturated, and it is toxic to rumen microorganisms so it could influence the composition of the rumen microbiome. It has been demonstrated that RF-DDGS is a suitable ration ingredient to support the high-producing dairy cow, and this feedstuff is a promising alternative protein source for lactating dairy cows. The current study aims to better understand the effect of RF-DDGS on the rumen and fecal bacterial composition in lactating dairy cows. Thirty-six multiparous (two or three), mid-lactation Holstein cows (BW = 680 ± 11 kg; 106 ± 27 DIM) were randomly assigned to two groups which were fed a control diet made up of corn, corn silage, and alfalfa hay supplemented with expeller soybean meal or with added RF-DDGS (20% of the DM) containing approximately 6.0% fat. Whole rumen contents (rumen fluid and digesta; esophageal tubing method) and feces (free-catch method) were collected on day 35 of the experimental period, after the 14-d acclimation period. Rumen contents and feces from each cow were used for DNA extraction. The bacterial community composition in rumen and fecal samples was assessed via the 16S rRNA gene by using the Illumina MiSeq sequencing platform. Bacteroidetes, Actinobacteria, and Firmicutes were the most abundant phyla in rumen contents. The fecal microbiota was dominated by the phyla Firmicutes and Bacteroidetes, as well as Actinobacteria and Chloroflexi. RF-DGGS increased bacterial richness, evenness, and Shannon diversity in both rumen and fecal samples and was associated with several taxa that had different abundance in treatment versus control comparisons. The RF-DGGS, however, did not significantly alter the bacterial community in the rumen or feces. In general, these findings demonstrated that dietary inclusion of RF-DDGS did not impose any serious short-term (within 30 days) health or production consequences, as would be expected. With this study, we present further evidence that inclusion of 20% (DM basis) RF-DDGS in the diet of lactating dairy cows can be done without consequence on the microbiome of the rumen.

Dankwa AS ，Humagain U ，Ishaq SL ，Yeoman CJ ，Clark S ，Beitz DC ，Testroet ED ... -  《-》

Bacterial Community Dynamics across the Gastrointestinal Tracts of Dairy Calves during Preweaning Development.

Microbial communities play critical roles in the gastrointestinal tracts (GIT) of preruminant calves by influencing performance and health. However, little is known about the establishment of microbial communities in the calf GIT or their dynamics during development. In this study, next-generation sequencing was used to assess changes in the bacterial communities of the rumen, jejunum, cecum, and colon in 26 crossbred calves at four developmental stages (7, 28, 49, and 63 days old). Alpha diversity differed among GIT regions with the lowest diversity and evenness in the jejunum, whereas no changes in alpha diversity were observed across developmental stage. Beta diversity analysis showed both region and age effects, with low numbers of operational taxonomic units (OTUs) shared between regions within a given age group or between ages in a given region. Taxonomic analysis revealed that several taxa coexisted in the rumen, jejunum, cecum, and colon but that their abundances differed considerably by GIT region and age. As calves aged, we observed lower abundances of taxa such as Bacteroides, Parabacteroides, and Paraprevotella with higher abundances of Bulleidia and Succiniclasticum in the rumen. The jejunum also displayed taxonomic changes with increases in Clostridiaceae and Turicibacter taxa in older calves. In the lower gut, taxa such as Lactobacillus, Blautia, and Faecalibacterium decreased and S24-7, Paraprevotella, and Prevotella increased as calves aged. These data support a model whereby early and successive colonization by bacteria occurs across the GIT of calves and provides insights into the temporal dynamics of the GIT microbiota of dairy calves during preweaning development.IMPORTANCE The gastrointestinal tracts (GIT) of ruminants, such as dairy cows, house complex microbial communities that contribute to their overall health and support their ability to produce milk. For example, the rumen microbiota converts feed into usable nutrients, while the jejunal microbiota provides access to protein. Thus, establishing a properly functioning GIT microbiota in dairy calves is critical to their productivity as adult cows. However, little is known about the establishment, maintenance, and dynamics of the calf GIT microbiota in early life. In this study, we evaluated the bacterial communities in the rumen, jejunum, cecum, and colon in dairy calves across preweaning development and show that they are highly variable early on in life before transitioning to a stable community. Understanding the dairy calf GIT microbiota has implications for ensuring proper health during early life and will aid in efforts to develop strategies for improving downstream production.

Dias J ，Marcondes MI ，Motta de Souza S ，Cardoso da Mata E Silva B ，Fontes Noronha M ，Tassinari Resende R ，Machado FS ，Cuquetto Mantovani H ，Dill-McFarland KA ，Suen G ... -  《-》

Comparison of rumen bacterial communities in dairy herds of different production.

Indugu N ，Vecchiarelli B ，Baker LD ，Ferguson JD ，Vanamala JKP ，Pitta DW ... -  《BMC MICROBIOLOGY》

Microbial succession in the gastrointestinal tract of dairy cows from 2 weeks to first lactation.

Dill-McFarland KA ，Breaker JD ，Suen G 《Scientific Reports》