In this paper, we examined the microbiome of the bovine rumen, feces, and milk and attempted to understand how the bacterial communities at each site affected the production and movement of vitamin B ₁₂ around the animal’s body. It was determined that the composition of the bovine rumen microbiome correlates well with vitamin B ₁₂ concentration, indicating that the rumen microbiota may be a good target for manipulation to improve production of this important vitamin.

Milk is an excellent source of vitamin B₁₂ (B12) for humans. Therefore, being able to guarantee a high and consistent concentration of this vitamin would enhance consumer perception of milk as a health food. The aim of the paper was to gather additional knowledge on factors that could explain B12 variation in cow milk through two observational studies: (1) to explore the relationship between milk B12 and ruminal conditions, such as pH and volatile fatty acid concentrations; and (2) to examine the impact of bedding on B12 concentrations in bulk tank milk. For study 1, a total of 72 milk and ruminal liquid samples were obtained from 45 Holstein cows fitted with ruminal cannula between 10 and 392 days of lactation. For study 2, bulk tank milk samples were obtained from 83 commercial herds; 26 herds used recycled manure solid bedding and 57 used straw bedding. Milk samples were analyzed for B12 using radioassay. Using principal component regression analysis, we observed that ruminal pH and the acetate:propionate ratio for cows receiving the early lactation ration were positively correlated with milk B12. Bedding did not influence milk B12 in bulk tanks, which averaged 4276 pg/mL. In conclusion, as B12 is synthesized by ruminal bacteria, optimizing ruminal conditions had a positive effect on milk B12, while bedding management had no influence.

Background: The frequency of chromosomal rearrangements in Canadian breeding boars has been estimated at 0.91 to 1.64%. These abnormalities are widely recognized as a potential cause of subfertility in livestock production. Since artificial insemination is practiced in almost all intensive pig production systems, the use of elite boars carrying cytogenetic defects that have an impact on fertility can lead to major economic losses. To avoid keeping subfertile boars in artificial insemination centres and spreading chromosomal defects within populations, cytogenetic screening of boars is crucial. Different techniques are used for this purpose, but several issues are frequently encountered, i.e. environmental factors can influence the quality of results, the lack of genomic information outputted by these techniques, and the need for prior cytogenetic skills. The aim of this study was to develop a new pig karyotyping method based on fluorescent banding patterns. Results: The use of 207,847 specific oligonucleotides generated 96 fluorescent bands that are distributed across the 18 autosomes and the sex chromosomes. Tested alongside conventional G-banding, this oligo-banding method allowed us to identify four chromosomal translocations and a rare unbalanced chromosomal rearrangement that was not detected by conventional banding. In addition, this method allowed us to investigate chromosomal imbalance in spermatozoa. Conclusions: The use of oligo-banding was found to be appropriate for detecting chromosomal aberrations in a Canadian pig nucleus and its convenient design and use make it an interesting tool for livestock karyotyping and cytogenetic studies.

Background:Genome assembly into chromosomes facilitates several analyses including cytogenetics, genomics and phylogenetics. Despite rapid development in bioinformatics, however, assembly beyond scaffolds remains challenging, especially in species without closely related well-assembled and available reference genomes. So far, four draft genomes of Rangifer tarandus (caribou or reindeer, a circumpolar distributed cervid species) have been published, but none with chromosome-level assembly. This emblematic northern species is of high interest in ecological studies and conservation since most populations are declining. Results:We have designed specific probes based on Oligopaint FISH technology to upgrade the latest published reindeer and caribou chromosome-level genomes. Using this oligonucleotide-based method, we found six mis-assembled scaffolds and physically mapped 68 of the largest scaffolds representing 78% of the most recent R. tarandus genome assembly. Combining physical mapping and comparative genomics, it was possible to document chromosomal evolution among Cervidaeand closely related bovids. Conclusions:Our results provide validation for the current chromosome-level genome assembly as well as resources to use chromosome banding in studies of Rangifer tarandus.