This study analyzed the diversity and phylogenetic relationship of the microbiome of bovine digital dermatitis (BDD) lesions and normal skin from cattle foot by using 16S rRNA amplicon sequencing. Three BDD samples and a normal skin sample were pre-assessed for analysis. The Illumina Miseq platform was used for sequencing and sequences were assembled and were categorized to operational taxonomic units (OTUs) based on similarity, then the core microbiome was visualized. The phylogeny was inferred using MEGA7 (Molecular evolutionary genetics analysis version 7.0). A total of 129 and 185 OTUs were uniquely observed in normal and in BDD samples, respectively. Of the 47 shared OTUs, 15 species presented increased abundance in BDD. In BDD and normal samples, Spirochetes and Proteobacteria showed the most abundant phyla, respectively, suggesting the close association of observed species in each sample group. The phylogeny revealed the evolutionary relationship of OTUs and the Euclidean distance suggested a high sequence divergence between OTUs. We concluded that a shift in the microbiome leads to richer diversity in BDD lesions, and the overabundance of opportunistic pathogens and its synergistic relationship with commensal bacteria could serve as factors in disease development. The influence of these factors should be thoroughly investigated in future studies to provide deeper insights on the pathogenesis of BDD.

This study aimed to isolate and characterize Treponema spp. from bovine digital dermatitis (BDD)-infected dairy cattle. Seven isolates were characterized in this study. Isolates exhibited slow growth, and colonies penetrated the agar and exhibited weak β-hemolysis. Round bodies were observed in old and antibiotic-treated cultures. Cells ranged from 9–12 µm in length, 0.2–2.5 µm in width, and were moderately spiraled. The 16S rRNA analysis revealed the isolates as Treponema phagedenis with >99% sequence homology. Isolates had alkaline phosphatase, acid phosphatase, β-galactosidase, N-acetyl-β-glucosaminidase, esterase (C4), esterase lipase (C8), naphthol-AS-BI-phosphohydrolase, and β-glucuronidase activities. Low concentrations of ampicillin, erythromycin, and tetracycline were required to inhibit the growth of isolates. Formic, acetic, and butyric acids were produced, while propionic acid was significantly utilized, indicating its essentiality for treponemal growth. The isolates shared the same characteristics and, therefore, were considered as a single strain. Isolate HNL4 was deposited as a representative isolate (Treponema phagedenis KS1). The average nucleotide identity of strain KS1 showed a small difference with the human strain (99.14%) compared with bovine strain (99.72%). This study was the first to isolate and characterize Treponema phagedenis from BDD in Korea and, hence, it delivered pathogenicity-related insights and provided valuable information that can be used for the management of BDD.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Md. Aftabuzzaman, Hector Espiritu, Seon-Ho Kim, Lovelia Mamuad, Su-Jeong Jin, Sang-Suk Lee, Yong-Il Cho. Korean J. Vet. Serv. 2021;44:321-6. https://doi.org/10.7853/kjvs.2021.44.4.321

Subclinical hypocalcemia (SCH) is traditionally associated with the transition period. However, emerging evidence suggests it may persist or recur throughout lactation. This study investigated the prevalence, metabolic profile, and risk factors for SCH in lactating dairy cows in South Korea. A cross-sectional analysis was conducted on 859 cows from 49 commercial dairy farms. SCH was defined as serum calcium ≤ 8.2 mg/dL. The individual-level prevalence was 9.4%, while 69.4% of herds had at least one affected cow, indicating widespread herd-level occurrence. SCH was significantly associated with parity, with cows in their fourth lactation or higher showing the highest prevalence. Although SCH prevalence did not differ significantly across lactation stages, early lactation cows had significantly lower mean serum calcium concentrations than those in later stages. Milk yield and composition did not differ significantly between groups. However, SCH cows showed notable metabolic differences, including higher serum phosphorus and lower albumin, total protein, and cholesterol levels, indicating potential energy and liver function challenges. Hematological values remained within physiological limits. These findings demonstrate that SCH can persist beyond the transition period, especially in older, high-producing cows, and may remain undetected by routine health checks. Broader monitoring and nutritional support are recommended to enhance metabolic resilience in at-risk animals.