Obihiro University of Agriculture and Veterinary Medicine
OAK Obihiro University Archives of KnowledgeNot a member yet
5082 research outputs found
Sort by
Genetic correlations among fertility traits and lactation persistency within and across Holstein herds with different milk production during the first three lactations✰
Get PDFapplication/pdfGenotype by environment interaction (G × E) effects for lactating cows’ fertility traits may differ with lactation number when accounting for herd production level. Our objective here was to investigate the genetic correlations among three fertility traits in cows and lactation persistency within and across herds with different milk-production levels by using lactation records of Japanese Holstein cows (475,446 records for first lactation, 378,540 for second, and 265,560 for third). Herds with data were categorized into three groups (LOW, MID, and HIGH) based on the average herd-year effects in each herd for 305-day milk yield at the first lactation. The fertility traits evaluated were conception rate at first insemination (CR); number of inseminations (NI); and days open (DO). Lactation persistency (PER) was defined as the difference between milk yields at 240 and 60 days in milk. Genetic parameters were estimated within each lactation by using a multiple-trait model that considered the traits of different herd milk-production groups (HPGs) as separate traits. The genetic correlations among fertility traits were estimated by using a three HPG × three-trait animal model; for those between fertility traits and PER we used a three HPG × two-trait (each fertility trait and PER) animal model. The genetic correlations among fertility traits were strong, whereas those between fertility traits and PER were weak and undesirable; most of the values did not differ significantly among HPGs or lactations. Some of the genetic correlations of CR or NI among different HPGs for the second and third lactations were lower than those for the first lactation. These findings suggest that G × E effects on a cow's ability to conceive with respect to herd production level are larger in later lactations than in the first lactation. © 2018journal articl
Bovine leukemia virus genotype 1 and 6 are circulating among dairy and beef cattle of small and medium holding farms in northern Vietnam
Get PDFapplication/pdfThe aims of this study were to determine the prevalence of bovine leukemia virus (BLV) infection among cattle in northern Vietnam, and to molecularly characterize the detected strains. Ninety-three blood samples (45 dairy and 48 beef cattle) were randomly collected from 464 cattle from 22 farms in four districts in northern Vietnam. The samples were tested for the presence of BLV by using two realtime PCR detection systems that targeted the BLV pol gene and tax gene. The samples were also tested for BLV antibody, using an ELISA kit. Nested PCR was designed to obtain the full-length nucleotide sequence of the BLV env gp51 gene. From the BLV pol gene real-time PCR and ELISA results, 33 of the 93 (35.48%) samples consistently tested positive for BLV infection. Phylogenetic analysis of the BLV env gp51 gene showed that the Vietnam strains were clustered into genotypes 1 and 6 (G1 and G6), of which G1 was dominant. Of three G6 strains detected, two were clearly distinguished from the known subgenotypes G6a-G6e and were therefore designated as a new subgenotype, G6f. Results of the phylogenetic analyses highlighted the requirement of the full-length env gp51 gene for reliable identification of the G6 strains. It was also noted that the commercial real-time PCR kit for the BLV tax gene failed to detect the Vietnam G6 strains, as was likewise previously reported for Myanmar BLV G10 strains. © 2019, Hokkaido University. All rights reserved.journal articl
Molecular characterization of a new Trypanosoma (Megatrypanum) theileri isolate supports the two main phylogenetic lineages of this species in Japanese cattle
Get PDFapplication/pdfTrypanosoma (Megatrypanum) theileri is a cosmopolitan, usually non-pathogenic, trypanosome of cattle transmitted by blood-sucking arthropods, mainly tabanid flies. Several T. theileri strains isolated from domestic and wild ruminants via co-culturing with mammalian feeder cells or blood cells have been characterized morphologically and genetically. Here, we cultured a new trypanosome isolate from a Holstein cow in Hokkaido, Japan, and performed morphological and molecular characterization studies. The new isolate (Obihiro strain) was co-cultivated with Madin–Darby bovine kidney (MDBK) cells in GIT medium supplemented with 10% fetal bovine serum. Trypomastigotes and epimastigotes, but not intracellular parasites, were identified in the culture. Analysis of the V7-V8 region of 18S rRNA sequences showed that the Obihiro strain is positioned within the subgenus Megatrypanum. A dendrogram based on whole internal transcribed spacer rDNA sequence showed that the Obihiro strain clustered in the lineage TthII together with the Japanese isolates of T. theileri, Esashi 9, and Esashi 12, and isolates from Zambia and the USA. T. theileri of the KM strain and a T. theileri-like trypanosome isolated from deer (TSD1 strain) clustered in the lineage TthI, separate from the Obihiro strain. Based on a partial cathepsin L-like protein gene analysis, the Obihiro strain clustered with isolates of the TthIIF genotype, which includes T. theileri from Vietnam, Sri Lanka, and Brazil. Our analyses of the T. theileri Obihiro strain provide relevant insights into its genetic diversity in Japanese cattle and corroborate the host specificity of cattle and deer trypanosomes of the subgenus Megatrypanum. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.journal articl
Activation of HSD11B1 in the bovine cumulus-oocyte complex during IVM and IVF
Get PDFapplication/pdfThe bovine cumulus-oocyte complex (COC) is capable of converting cortisone, an inert glucocorticoid to active cortisol. This mechanism is mediated by 11β-hydroxysteroid oxidoreductase type 1 (HSD11B1), whose expression dramatically increases in the mature COC. In this study, we investigate the time course expression of HSD11B1 and the enzyme activity in the bovine COC undergoing maturation and fertilization in relation to key events taking place in the COC. Bovine COCs were subjected to in vitro maturation (IVM) and fertilization (IVF). The activities of HSD11B1 and HSD11B2, which mediates the opposite reaction, were measured using a radiometric conversion assay. In parallel studies, cumulus expansion, P4 production and the expression of genes associated with ovulation were measured. The reductive activity of HSD11B1 increased in the latter half of IVM and remained high during IVF, whereas the oxidative activity of HSD11B2 remained unchanged over both periods. Consequently, the net glucocorticoid metabolism in the bovine COC shifted from inactivation to activation around the time of ovulation and fertilization. The increase in HSD11B1 expression lagged behind that of P4 increase and cumulus expansion but ahead of the expressions of genes responsible for PGE2 synthesis. The reductive activity of HSD11B1 was well correlated with the cumulus expansion rate. This outcome indicates that the ability of the cumulus to activate glucocorticoids is related to its ability to synthesize hyaluronan. These results also indicate that the activation of HSD11B1 is an integral part of the sequential events taking place at the ovulation and fertilization in the bovine COC.journal articl
Variovorax sp. Has an optimum cell density to fully function as a plant growth promoter
Get PDFapplication/pdfUtilization of plant growth-promoting bacteria colonizing roots is environmentally friendly technology instead of using chemicals in agriculture, and understanding of the effects of their colonization modes in promoting plant growth is important for sustainable agriculture. We herein screened the six potential plant growth-promoting bacteria isolated from Beta vulgaris L. (Rhizobium sp. HRRK 005, Polaromonas sp. HRRK 103, Variovorax sp. HRRK 170, Mesorhizobium sp. HRRK 190, Streptomyces sp. HRTK 192, and Novosphingobium sp. HRRK 193) using a series of biochemical tests. Among all strains screened, HRRK 170 had the highest potential for plant growth promotion, given its ability to produce plant growth substances and enzymes such as siderophores and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, respectively, concomitantly with active growth in a wider range of temperatures (10–30◦ C) and pH (5.0–10.0). HRRK 170 colonized either as spots or widely on the root surface of all vegetable seedlings tested, but significant growth promotion occurred only in two vegetables (Chinese cabbage and green pepper) within a certain cell density range localized in the plant roots. The results indicate that HRRK 170 could function as a plant growth promoter, but has an optimum cell density for efficient use.journal articl
肝障害の回復期に光線過敏症がみられたホルスタイン種育成牛の1症例
Get PDFapplication/pdf放牧中のl歳2カ月齢のホルスタイン種育成牛が突然の起立不能を呈し、ASTの著しい増加（4900U/l)および第3病日からの黄痘が認められたため、急性肝障害を疑った。ステロイドや解毒剤を用いた治療の継続により、一般状態は徐々に回復したが、第13病日に再び悪化し、皮膚白色部の被毛粗剛、皮膚硬結、ひび割れがみられた。症例は衰弱し、皮膚病変も改善せず、第16病日には再度起立不能を呈した。第18病日にはASTが180U/lとなり、初診日と比較して著しい低下を認めた。その後、第19病日に病性鑑定が行われた。病理学的検査により、皮膚白色部の角化允進、廃嫡～潰蕩、表皮直下水腫および線維化が観察された。肉眼的および組織学的に肝臓に顕著な異常はみられなかった。本症例は放牧牛であり、発症が10月という点から、有毒植物摂取による急性肝障害が疑われ、皮膚病変は肝原性光線過敏症と考えられた。しかし、病理学的検査において肝臓に病変がみられなかったことから、肝原性光線過敏症は肝障害の回復期にも発現する可能性が考えられた。journal articl