Environmental temperature is one of the important abiotic factors that influence the normal physiological function and productive performance of dairy cattle. Temperature stress evokes complex responses that are essential for safeguarding of cellular integrity and animal health. Post-transcriptional regulation of gene expression by miRNA plays a key role cellular stress responses. The present study investigated the differential expression of miRNA in Frieswal (Holstein Friesian × Sahiwal) crossbred dairy cattle that are distinctly adapted to environmental temperature stress as they were evolved by using the temperate dairy breed Holstein Friesian. The results indicated that there was a significant variation in the physiological and biochemical indicators estimated under summer stress. The differential expression of miRNA was observed under heat stress when compared to the normal winter season. Out of the total 420 miRNAs, 65 were differentially expressed during peak summer temperatures. Most of these miRNAs were found to target heat shock responsive genes especially members of heat shock protein (HSP) family, and network analysis revealed most of them having stress-mediated effects on signaling mechanisms. Being greater in their expression profile during peak summer, bta-miR-2898 was chosen for reporter assay to identify its effect on the target HSPB8 (heat shock protein 22) gene in stressed bovine PBMC cell cultured model. Comprehensive understanding of the biological regulation of stress responsive mechanism is critical for developing approaches to reduce the production losses due to environmental heat stress in dairy cattle.

Zebu (Bos indicus) is a domestic cattle species originating from the Indian subcontinent and now widely domesticated on several continents. In this study, we were particularly interested in understanding the functionally active rumen microbiota of an important Zebu breed, the Gir, under different dietary regimes. Metagenomic and metatranscriptomic data were compared at various taxonomic levels to elucidate the differential microbial population and its functional dynamics in Gir cattle rumen under different roughage dietary regimes. Different proportions of roughage rather than the type of roughage (dry or green) modulated microbiome composition and the expression of its gene pool. Fibre degrading bacteria (i.e. Clostridium, Ruminococcus, Eubacterium, Butyrivibrio, Bacillus and Roseburia) were higher in the solid fraction of rumen (P<0.01) compared to the liquid fraction, whereas bacteria considered to be utilizers of the degraded product (i.e. Prevotella, Bacteroides, Parabacteroides, Paludibacter and Victivallis) were dominant in the liquid fraction (P<0.05). Likewise, expression of fibre degrading enzymes and related carbohydrate binding modules (CBMs) occurred in the solid fraction. When metagenomic and metatranscriptomic data were compared, it was found that some genera and species were transcriptionally more active, although they were in low abundance, making an important contribution to fibre degradation and its further metabolism in the rumen. This study also identified some of the transcriptionally active genera, such as Caldicellulosiruptor and Paludibacter, whose potential has been less-explored in rumen. Overall, the comparison of metagenomic shotgun and metatranscriptomic sequencing appeared to be a much richer source of information compared to conventional metagenomic analysis.

In dromedary camels, which are pseudo-ruminants, rumen or C1 section of stomach is the main compartment involved in fiber degradation, as in true ruminants. However, as camels are adapted to the harsh and scarce grazing conditions of desert, their ruminal microbiota makes an interesting target of study. The present study was undertaken to generate the rumen microbial profile of Indian camel using 16S rRNA amplicon and shotgun metagenomics. The camels were fed three diets differing in the source of roughage. The comparative metagenomic analysis revealed greater proportions of significant differences between two fractions of rumen content followed by diet associated differences. Significant differences were also observed in the rumen microbiota collected at different time-points of the feeding trial. However, fraction related differences were more highlighted as compared to diet dependent changes in microbial profile from shotgun metagenomics data. Further, 16 genera were identified as part of the core rumen microbiome of Indian camels. Moreover, glycoside hydrolases were observed to be the most abundant among all Carbohydrate-Active enzymes and were dominated by GH2, GH3, GH13 and GH43. In all, this study describes the camel rumen microbiota under different dietary conditions with focus on taxonomic, functional, and Carbohydrate-Active enzymes profiles.