Relun, A. | bioRxiv Science

bioRxiv2023

Massive detection of cryptic recessive genetic defects in cattle mining millions of life histories

We present a data-mining framework designed to detect recessive defects in livestock that have been previously missed due to a lack of specific signs, incomplete penetrance, or incomplete linkage disequilibrium. This approach leverages the massive data generated by genomic selection. Its basic principle is to compare the observed and expected numbers of homozygotes for sliding haplotypes in animals with different life histories. Within three cattle breeds, we report 33 new loci responsible for increased risk of juvenile mortality and present a series of validations based on large-scale genotyping, clinical examination, and functional studies for candidate variants affecting the NOA1, RFC5, and ITGB7 genes. In particular, we describe disorders associated with NOA1 and RFC5 mutations for the first time in vertebrates. The discovery of these many new defects will help to characterize the genetic basis of inbreeding depression, while their management will improve animal welfare and reduce losses to the industry.

genetics↗

bioRxiv2019

Do footbath disinfectants modify the dynamics of the skin microbiota in dairy cattle affected by digital dermatitis?

Bovine digital dermatitis (DD), is a highly prevalent disease among dairy cattle characterized by ulcerative and painful lesions. While multiple management factors are involved in the disease, its precise etiology remains uncertain and the effectiveness of current control strategies remains highly variable. The major role of Treponema spp. in the development of the disease is consistently recognized. Nevertheless, it remains unclear how other bacterial communities are relevant to the onset and progression of the disease, and how the skin microbiota is affected by the environment during the course of the disease. The objective of this study was to describe the dynamics of microbiota recovered from DD affected feet under field conditions. This study described the diversity, structure, and composition of DD lesion microbiota over 45 days according to different clinical and management factors. The results of this investigation confirmed the existence of a specific skin microbiota associated with DD lesions, dominated by Treponema spp. and very different from the microbiota of healthy skin. Interestingly, the diversity and structure of the microbiota in DD lesions did not vary with the footbath disinfectant or the individual topical antibiotic treatments used. In addition, microbiotas from proliferative lesions evidenced a different structure and diversity in comparison to non-proliferative lesions. Our results confirm the major role of Treponema spp. And highlight the potential role of Mycoplasmopsis spp. in the DD lesion onset. Further studies are needed to confirm whether the clinical course of DD lesions is driven by a particular microbiota and how that microbiota may induce disease. HighlightsMultiple bacteria have been identified in DD lesions. However, many of these microorganisms are inhabitants of the foot skin and the farm environment. For the first time, the microbiota of DD lesions was monitored for 45 days under field conditions to describe its evolution over time. The results of this investigation highlighted a particular microbiota dominated by Treponema spp. present on the skin of DD affected animals and highly different from those microbiotas of healthy skin. The microbiota of DD lesions evolved over the study period and differential bacteria were identified. Further studies are warranted to determine the role of the bacteria composing these microbiotas on lesion onset and outcome.

microbiology↗