Disposition Kinetics of Difloxacin After Intravenous,Intramuscular and Subcutaneous Administration in Calves

The pharmacokinetics of difloxacin (Dicural) was studied in a crossover study using three groups (n = 4) of male and female Friesian calves after intravenous (i.v.), intramuscular (i.m.) and subcutaneous (s.c.) administrations of 5 mg/kg body weight. Drug concentration in plasma was determined by high-performance liquid chromatography using fluorescence detection. The plasma concentration–time data following i.v. administration were best fitted to a two-compartment open model and those following i.m. and s.c. routes were best fitted using one-compartment open model. The collected data were subjected to a computerized kinetic analysis. The mean i.v., i.m. and s.c. elimination half-lives (t _1/2β) were 5.56 ± 0.33 h, 6.12 ± 0.42 h and 7.26 ± 0.6 h, respectively. The steady-state volume of distribution (V _dss) was 1.12 ± 0.09 L/kg and total body clearance (Cl_B) was 2.19 ± 0.1 ml/(min. kg). The absorption half lives (t _1/2ab) were 0.38 ± 0.027 h and 2.1 ± 0.09 h, with systemic bioavailabilities (F) of 96.5% ± 6.4% and 84% ± 5.5% after i.m. and s.c. administration, respectively. After i.m. and s.c. dosing, peak plasma concentrations (C _max) of 3.38 ± 0.13 μg/ml and 2.18 ± 0.12 μg/ml were attained after (t _max) 1.22 ± 0.20 h and 3.7 ± 0.52 h. The MIC₉₀ of difloxacin for Mannheimia haemolytica was 0.29 ± 0.04 μg/ml. The AUC/MIC₉₀ and C _max/MIC₉₀ ratios for difloxacin following i.m. administration were 120 and 11.65, respectively and following s.c. administration were 97.58 and 7.51, respectively. Difloxacin was 31.7–36.8% bound to calf plasma protein. Since fluoroquinolones display concentration-dependent activities, the doses of difloxacin used in this study are likely to involve better pharmacodynamic characteristics that are associated with greater clinical efficacy following i.m. administration than following s.c. administration.     

Mannheimia haemolytica serotype A1 exhibits differential pathogenicity in two related species, Ovis canadensis and Ovis aries

Mannheimia haemolytica causes pneumonia in both bighorn sheep (BHS, Ovis canadensis) and domestic sheep (DS, Ovis aries). Under experimental conditions, co-pasturing of BHS and DS results in fatal pneumonia in BHS. It is conceivable that certain serotypes of M. haemolytica carried by DS are non-pathogenic to them, but lethal for BHS. M. haemolytica serotypes A1 and A2 are carried by DS in the nasopharynx. However, it is the serotype A2 that predominantly causes pneumonia in DS. The objectives of this study were to determine whether serotype A1 exhibits differential pathogenicity to BHS and DS, and to determine whether leukotoxin (Lkt) secreted by this organism is its primary virulence factor. Three groups each of BHS and DS were intra-tracheally administered either 1 x 10(9)cfu of serotype A1 wild-type (lktA-Wt group), Lkt-deletion mutant of serotype A1-(lktA-Mt group), or saline (control group), respectively. In the lktA-Wt groups, all four BHS died within 48h while none of the DS died during the 2-week study period. In the lktA-Mt groups, none of the BHS or DS died. In the control groups, one DS died due to an unrelated cause. Necropsy and histopathological findings revealed that death of BHS in the lktA-Wt group was due to bilateral, fibrinohemorrhagic pneumonia. Although the A1-Mt-inoculated BHS were clinically normal, on necropsy, lungs of two BHS showed varying degrees of mild chronic pneumonia. These results indicate that M. haemolytica serotype A1 is non-pathogenic to DS, but highly lethal to BHS, and that Lkt is the primary virulence factor of M. haemolytica.     

Effect of Different Culture Ways on Health and Development of Japanese Black Calves

The test was conducted to study the effect of different culture ways on health and development of Japanese Black calves in cold area,20 healthy and newborn calves were divided into 2 groups using single factor randomized block design.Calves of control group were fed using traditional feeding method while calves of experimental group were fed using artificial feeding method.The test period was 180 d,body weight and body steep size indexes of calves were measured,and the health condition of calves were observed.The results showed that when weaned at 3 months old,body weight and average daily gain of calves in experimental group were significantly higher than that of control group (P<0.05);Body weight and average daily gain of calves with 6 months old in experimental group were significantly higher than that of control group (P<0.05);The fecal index,diarrhea rate,diarrhea frequency and death rate of experimental group were lower than that of control group,and the difference of diarrhea rate and diarrhea frequency were significant (P<0.05).And the respiratory disease incidence,incidence frequency and death rate of experimental group were lower than that of control group,the difference of the three indexes were significant (P<0.05).The results suggested that artificial feeding method could improve the Japanese Black calves survival rate,strengthen the prevention of diarrhea and respiratory disease and sufficiently play the potential to improve calf weaning weight.It not only could reduce the economic costs of farms,and also significantly improve the economic efficiency of domestic high-quality beef cattle.     

培育方式对和牛犊牛健康及生长发育的影响

本试验旨在研究在寒冷地区不同培育方式对和牛犊牛健康及生长发育的影响。选取20头健康、初生的和牛犊牛,采用单因素随机分组设计,分为2组。对照组采用母牛带犊自然哺乳方式培育犊牛,试验组采用人工哺乳方式培育犊牛。试验期为180 d,定期测定犊牛体重和体尺指标,观察犊牛健康状况。结果显示,犊牛在3月龄断奶时,试验组犊牛断奶体重及日增重显著高于对照组（P<0.05）;试验组6月龄时体重及日增重显著高于对照组（P<0.05）;对照组犊牛粪便指数、腹泻率、腹泻频率及死亡率均高于试验组的犊牛,其中腹泻率与腹泻频率两组间差异显著（P<0.05）。对照组犊牛呼吸系统疾病发病率、发病频率及死亡率也均高于试验组犊牛,且均差异显著（P<0.05）。结果提示,人工饲养培育和牛犊牛提高了和牛犊牛成活率,降低了犊牛腹泻和犊牛呼吸道疾病等的发病率,可充分发挥提高犊牛断奶体重的潜力,不仅降低了养殖和牛的经济成本,也提高优质肉牛的经济效益。     

Comparison of the peripheral blood leukocyte population between Japanese Black and Holstein calves

Japanese black (JB) calves have greater susceptibility to infectious diseases compared to Holstein (Hol) calves. In order to clarify the differences in cellular immune status between JB and Hol calves, the leukocyte population and lymphocyte proliferative ability were analyzed. In total 200 healthy calves, 1 day to 14 weeks of age, were examined: 105 JB and 95 Hol calves. Lower numbers in peripheral blood and percentage in peripheral blood mononuclear cells of CD3⁺TcR1‐N12⁺ T cells and major histocompatibility complex class‐II⁺CD14^‐ B cells were observed in the JB compared to the Hol. The percentage of TcR1‐N12⁺CD25⁺ T cell in the JB was significantly lower than that of the Hol at 4–6, and 8–10 weeks. Interleukin (IL)‐2 sensitivity in the JB was lower than that in the Hol, and significant differences were observed in age groups of 6–8 weeks and 10–14 weeks. These findings indicated that the lower numbers of γδ T cells and B cells in the JB compared to the Hol might be associated with the specificity of the immune systems in JB calves.     

Comparison of cytokine mRNA expression in peripheral CD4+, CD8+ and γδ T cells between healthy Holstein and Japanese Black calves

Japanese Black (JB) calves are more susceptible to infectious diseases compared to Holstein (Hol) calves. To clarify the immunological differences between JB and Hol calves, expression of cytokine messenger RNA (mRNA) was examined using peripheral CD4⁺, CD8⁺ and γδ T cells. Healthy calves, 24 from each species, were examined. Blood samples were obtained from calves at 1 week, 1 month and 3 months old, eight calves for each age of each species. Peripheral blood mononuclear cells were stimulated with phytohemagglutin (PHA), and T cell subsets were isolated by positive selection using magnetic cell sorting (MACS). Levels of interlekin (IL)‐2, IL‐4, IL‐10 and interferon (IFN)‐γ mRNA in three T cell subsets were analyzed. WC1‐N1⁺ γδ T cell percentages were significantly lower in JB calves at 1 week and 1 month of age compared to Hol calves. In addition JB calves had significantly lower IL‐2, IL‐10 and IFN‐γ mRNA in WC1‐N1⁺ γδ T cells at 1 and 3 months of age, whereas there were no significant differences in cytokine mRNA of CD4⁺ and CD8⁺ cells between the two groups. Decreased cytokine mRNA and cell number of peripheral γδ T cells may affect negatively on the immune system of JB calves.     

Yersiniosis caused by Yersinia pseudotuberculosis in captive toucans (Ramphastidae) and a Japanese squirrel (Sciurus lis) in zoological gardens in Japan

Two captive Keel-billed toucans and a Chestnut-mandibled toucan in another zoological garden died suddenly without any pre-existing symptoms, and three months later, a Japanese squirrel died of diarrhea. All these animals showed necrotic enteritis and multifocal necrosis in the liver and spleen with Gram negative bacilli. The bacilli showed strong positive immunolabeling for Yersinia pseudotuberculosis O4 in the Keel-billed toucans, Y. pseudotuberculosis O2 in the Chestnut-mandibled toucan and Y. pseudotuberculosis O1 in the Japanese squirrel, while Y. pseudotuberculosis 4b, 2b and 1b were respectively isolated from the lesions. To our knowledge, this might be the first reported case of fatal yersiniosis in a Japanese squirrel in the world as well as in toucans in Japan.     

Estimation of direct and maternal genetic parameters for growth and carcass traits in a herd of Japanese Black cattle in Miyagi prefecture, using a multitrait animal model

Data from 1170 records of fattening calves were collected on growth and carcass traits from a Japanese Black cattle herd located in Miyagi prefecture, Japan. The objective was to determine direct and maternal heritabilities, direct and maternal genetic correlations and phenotypic correlations between bodyweight at the beginning of the fattening period (BWS), bodyweight at the end of the fattening period (BWF), carcass weight (CW), average daily gain during the fattening period (ADG), rib eye area (REA), rib thickness, subcutaneous backfat thickness (SFT), yield estimate (YE) and beef marbling score (BMS). Direct heritability estimates of 0.16 (SFT) and 0.07 (BMS) were low, whereas estimates of the other traits were medium to high and ranged between 0.44 (REA) and 0.78 (CW). Direct genetic correlations were all positive, except those that were between BWS and SFT, and between BWS and YE (?0.49 and ?0.14, respectively). The lowest positive genetic correlation was between BWS and BMS (0.04) and the highest was between BWF and CW (0.99). The phenotypic correlation coefficients ranged between ?0.41 (between SFT and YE) and 0.96 (between BWF and CW). Maternal heritability estimates were generally low and ranged between 0.00 for BMS and 0.08 for BWS, CW and ADG. Selection programs comprising information on growth and carcass traits of calves and maternal traits of dams were suggested.     

Three cases of idiopathic eosinophilic enteritis with chronic obstinate diarrhea in Japanese Black fattening cattle

Eosinophilic enteritis (EOE) is a type of inflammatory bowel disease and is characterized clinically by chronic obstinate diarrhea. Three Japanese Black (JB) fattening cattle (2 males and 1 female) on different cattle farms presented with chronic episodic diarrhea without fever or dehydration. Soft reddish spherical carneous tissues (1−3 cm) were occasionally excreted within the diarrheic feces. Administration of antibiotics, antidiarrheal drugs and vermicides had no therapeutic effect, but dexamethasone improved the fecal characteristics. The symptoms persisted until the animals were slaughtered at 27–30 months of age. Histopathological examination of the intestines revealed marked eosinophilic infiltration in the lamina propria and submucosa. From these findings, we diagnosed these cattle as the first cases of EOE in JB cattle.     

Transmission of Mannheimia haemolytica from the tonsils of lambs to the teat of ewes during sucking

Objective of the work was to study whether Mannheimia haemolytica may be transmitted from the mouth of the lambs into the teat of the dam during sucking. We compared bacterial populations within the teat duct and milk of ewes immediately before and immediately after sucking by the lambs. Tonsils of lambs of the ewes were swabbed. M. haemolytica strain DAG21T recovered from a teat duct of a ewe was compared to strain DAG21R recovered from the tonsils of her lamb by using 16s rRNA sequencing. We used those two isolates and another one of known pathogenicity, for challenging ewes: (i) 2-mm deep into healthy teats, (ii) 2-mm deep into teats with chapping lesions or (iii) into the cistern of healthy mammary glands. Of samples collected before suckling, 20/792 were bacteriologically positive, and of those after, 50/792 were bacteriologically positive (P < 0.001); in 37 cases, a negative sample became positive. One M. haemolytica (DAG21T) was recovered after suckling from a teat duct of a ewe. The organism was isolated from 57/90 tonsillar swabs from lambs. Risk of infection of ewe’ teats was 0.004 throughout lactation, being greatest (0.021) during the 3rd week of lactation. The 16s rRNA sequences of strains DAG21T and DAG21R were identical over 1450 nucleotides. Phylogenetic analysis showed that the two isolates clustered together with isolates of M. haemolytica. Organism deposition into healthy teats caused subclinical mastitis; deposition into teats with lesions or directly into mammary gland caused clinical mastitis. When results of inoculation of the three strains were compared between them, statistical significance was always P > 0.9. Results provide clear evidence that suckling by lambs can lead to transmission of M. haemolytica into the teats of the ewes; the bacteria have the potential to cause mastitis if circumstances are favourable.     

Estimation of dominance genetic variances for reproductive traits and growth traits of calves in Japanese Black cattle

The dominance genetic effects for reproductive and calf growth abilities in the practical Japanese Black populations were examined using average information (AI) algorithm restricted maximum likelihood (REML) under animal models. The reproductive traits were observed in Japanese Black cattle maintained at Tottori and Okinawa prefectures, and growth traits of calves were observed in cattle at Okinawa. The average of dominance relationships in Tottori ranged from 0.2 to 0.4%, while the level in Okinawa was lower and sparse compared with Tottori. The proportions of the dominance variances to sum of additive and dominance variances () were all 0.02 for reproductive traits in Tottori. In contrast, the proportion was 0.02–0.64 in Okinawa regardless of the level of dominance relationships. These proportions suggested that the dominance might affect the expression of calving interval, days open and gestation length in Okinawa, where breeding units were spread over many islands. Although the dominance variances could not estimate birthweight, w as 0.34 for calf market weight and 0.27 for average daily gain from birth to calf market in Okinawa. These values also suggested that the dominance might affect the early growth of calves. In the near future, genetic relationships will become more complicated with continuation of the current selection and mating systems. Therefore, genetic evaluation accounting for dominance effects would be necessary for particular traits and populations.     

Stimulation and analysis of the immune response in calves from vaccinated pregnant cows

The effect of vaccinating pregnant cows with an inactivated vaccine against Mannheimia haemolytica, BRSV and PI3V infections on selected immune responses in their offspring was examined. Blood samples were collected weekly for 12 weeks from six newborn calves from each of vaccinated (experimental) and unvaccinated (control) dams. Specific antibodies to M. haemolytica, BRSV and PI3V and mean values of IgA, IgG concentrations were significantly higher in the experimental calves compared with the controls. However, specific antibody titres to adenovirus type 3, BHV1 and BVDV in the experimental calves had constant levels while the control group levels changed. The IgM, Hp and SAA concentrations generally increased until week 8 in the experimental group, but the control group titres became higher after week 9. This study demonstrates that specific immunisation of cows pre-partum significantly stimulated parameters associated with immunity and it also controlled the acute phase response intensity in their offspring. Therefore the vaccination of dams may provide additional antibody protection against infection to their offspring.     

渤海黑牛和日本和牛MSTN基因的比较分析

利用PCR扩增及测序的方法,分别对渤海黑牛和日本和牛的MSTN基因编码序列进行分析。结果显示:与日本和牛相比,渤海黑牛MSTN基因外显子1的111 bp处存在一个突变位点,在其外显子2和外显子3处进行比较分析,发现与NCBI上牛的序列一致,没有发生改变的位点。     

Forestomach developmental failure in an 11-month-old Japanese Black steer with severely retarded growth and chronic ruminal tympany

This study reports findings from the pathological examination of the forestomach of an 11-month-old Japanese Black steer with severely retarded growth (41% of expected weight) and chronic ruminal tympany. The ruminal papillae were weakly formed (0.3–0.5 cm long) and unevenly distributed. The cellulae and cristae reticuli were underdeveloped; the cristae were 0.4–0.7 cm in height and milky white. The keratinized layer in the stratified squamous epithelium was thickened. Ruminal pH was 5.25, and ruminal volatile fatty acid concentration was 11.7 mM. The steer’s severely retarded growth was considered to be caused by malnutrition due to developmental and functional failure of the forestomach.     

Genome‐wide association study for fatty acid composition in Japanese Black cattle

Fatty acid composition is one of the important traits in beef. The aim of this study was to identify candidate genomic regions for fatty acid composition by genome‐wide association study with 50 K single nucleotide polymorphism (SNP) array in Japanese Black cattle. A total of 461 individuals and 40 657 SNPs were used in this study. We applied genome‐wide rapid association using mixed model and regression (GRAMMAR) and genomic control approaches to estimate the associations between genotypes and fatty acid composition. In addition, two SNPs in fatty acid synthase (FASN) (T1952A) and stearoyl‐CoA desaturase (SCD) (V293A) genes were also genotyped. Association analysis revealed that 30 significant SNPs for several fatty acids (C14:0, C14:1, C16:1 and C18:1) were located in the BTA19 FASN gene located within this region but the FASN mutation had no significant effect on any traits. We also detected one significant SNP for C18:1 on BTA23 and two SNPs for C16:0 on BTA25. The region around 17 Mb on BTA26 harbored two significant SNPs for C14:1 and SNP in SCD in this region showed the strongest association with C14:1. This study demonstrated novel candidate regions in BTA19, 23 and 25 for fatty acid composition.