Analysis of Acute Phase Response Using Acute Phase Proteins Following Simultaneous Vaccination of Lumpy Skin Disease and Foot-and-Mouth Disease.

Since 2011, South Korea has implemented biannual vaccinations against foot-and-mouth disease (FMD) and recently, lumpy skin disease (LSD), to mitigate the spread of transboundary animal diseases. However, due to past adverse reactions, potentially linked to acute phase responses from FMD vaccinations, there is hesitancy among Korean livestock farmers regarding new strategies for simultaneous vaccinations against both FMD and LSD. This study was conducted to assess possible adverse reactions to the LSD vaccination by analyzing acute phase proteins (APPs) in three groups: cows vaccinated against FMD (G1-FMDV), LSD (G2-LSDV), and both (G3-FMDV/LSDV). In G1-FMDV, APP levels peaked on day 3 post-vaccination (p < 0.001) and returned to baseline. In G2-LSDV, APP levels increased gradually, peaking on day 10 post-vaccination. In G3-FMDV/LSDV, APP levels peaked on day 3 post-vaccination and remained high until day 10 (p < 0.001). These results indicate that LSD vaccines trigger a later immune response compared to FMD vaccines, possibly due to different adjuvants. Therefore, a longer follow-up period for monitoring adverse reactions to LSD vaccinations may be required to understand and mitigate potential risks.

Application of tenotomy on Korean native cattle (Hanwoo) with spastic paresis symptoms in the field.

Bovine spastic paresis (BSP) is a neuromuscular disorder characterized by hypertension and stiffness of hindlimb. Two Korean native cattle (Hanwoo) calves developed BSP or BSP-like symptoms, and a tenotomy of superficial tendon of medial head and deep tendon of lateral head of gastrocnemius muscle was performed for treatment. A cast was applied postoperatively to prevent muscle rupture and was removed three weeks later. The prognosis was evaluated at 3 weeks, 6 and 18 months postoperatively. Neither calf showed any other postoperative sequelae. This is the first case study to report the diagnosis, treatment, and prognosis of BSP in Hanwoo.

Comparison of prepartum blood parameters in dairy cows with postpartum ketosis and new risk prediction candidates.

Introduction: Ketosis is a predominant metabolic problem and a risk factor for several postpartum diseases. This retrospective study aimed to evaluate the complete blood count (CBC), plasma biochemistry, and osteocalcin and identify significant prepartum and early postpartum values expressed in ketotic cows. Methods: In 135 Holstein Friesian cows, 210 parturitions of 114 primiparous and 96 multiparous cows were examined. According to the plasma concentrations of ß-hydroxybutyrate (BHB; ≥ 1.4 mmol/L) or non-esterified fatty acids (NEFA; ≥ 0.7 mmol/L) in the postpartum period, cows were divided into healthy cows (CON) and ketotic cows (KET). Analyses of CBC and biochemistry profiles were performed from -6 to 4 weeks of parturition every 2 weeks (prepartum; BW-5, BW-3, and BW-1, postpartum; BW1 and BW3), and osteocalcin ELISA tests were performed using blood samples from -2 to 2 weeks of parturition (BW-1 and BW1). Results: In primiparous KET (n = 114) before parturition, lower lymphocyte (Lym) in BW-5 and BW-3, lower red blood cell (RBC) in BW-5, higher mean corpuscular volume (MCV) in BW-1, and higher NEFA in BW-3 were significant compared with CON. Primiparous KET showed lower carboxylated osteocalcin (cOC) levels and a significant decrease after parturition. In multiparous KET (n = 96) before parturition, lower neutrophil (Neu) in BW-5, higher hemoglobin (HGB) in BW-5, higher MCV in BW-5 and BW-1, higher MCH in BW-5, lower total cholesterol (TC) in BW-5, higher triglyceride (TG) in BW-3, higher NEFA in BW-1, higher glucose (Glu) in BW-3, lower γ-glutamyl transferase (GGT) in BW-5, lower inorganic phosphate (iP) in BW-3, and higher body condition score (BCS) in BW-5 and BW-3 were significant compared with CON. Multiparous KET showed decreased cOC and uncarboxylated osteocalcin (ucOC) after parturition, which was lower than that in the CON group. Discussion: The blood parameters expressing different values between CON and KET in prepartum or early postpartum periods are presumed to show individual nutrition and health states, liver function, and overweight status. These parameters could be valuable indicators that can be used to prevent the occurrence of ketosis and improve management practices by recognizing these differences in ketotic cows before calving.

Rapid Screening and Comparison of Chimeric Lysins for Antibacterial Activity against Staphylococcus aureus Strains.

Chimeric lysins composed of various combinations of cell wall-lysing (enzymatic) and cell-wall-binding (CWB) domains of endolysins, autolysins, and bacteriocins have been developed as alternatives to or adjuvants of conventional antibiotics. The screening of multiple chimeric lysin candidates for activity via E. coli expression is not cost effective, and we previously reported on a simple cell-free expression system as an alternative. In this study, we sufficiently improved upon this cell-free expression system for use in screening activity via a turbidity reduction test, which is more appropriate than a colony reduction test when applied in multiple screening. Using the improved protocol, we screened and compared the antibacterial activity of chimeric lysin candidates and verified the relatively strong activity associated with the CHAP (cysteine, histidine-dependent amidohydrolase/peptidase) domain of secretory antigen SsaA-like protein (ALS2). ALS2 expressed in E. coli showed two major bands, and the smaller one (subprotein) was shown to be expressed by an innate downstream promoter and start codon (ATG). The introduction of synonymous mutations in the promoter resulted in clearly reduced expression of the subprotein, whereas missense mutations in the start codon abolished antibacterial activity as well as subprotein production. Interestingly, most of the S. aureus strains responsible for bovine mastitis were susceptible to ALS2, but those from human and chicken were less susceptible. Thus, the simple and rapid screening method can be applied to select functional chimeric lysins and define mutations affecting antibacterial activity, and ALS2 may be useful in itself and as a lead molecule to control bovine mastitis.

Evaluation of Corpus Luteum and Plasma Progesterone the Day before Embryo Transfer as an Index for Recipient Selection in Dairy Cows.

The aim of the present study was to evaluate the effects of synchronization method, season, parity, corpus luteum (CL) size, and progesterone (P4) levels on the pregnancy rate after bovine embryo transfer (ET). Among 165 recipient candidates who received 1 of 2s estrus synchronization treatments, 96 heifers and 43 cows were selected through rectal examination and used as recipients. The day before ET, the CL size and plasma P4 concentration were evaluated. The CL sizes and plasma P4 levels were not different between the selected and unselected candidates, and the pregnancy rates with the two synchronization methods were not different. However, the pregnancy rates were higher in heifers than in lactating cows, and also higher after ET performed from September to February than from March to August (p < 0.05). The recipients with a CL larger than 1.5 cm showed statistically higher pregnancy rates, and although there was no statistical significance, the pregnancy rate was higher when the plasma P4 levels were between 2.0 and 4.0 ng/mL. Exposure to a stressful environment and repeated manipulations can reduce the success rate of ET, and recipient selection with an optimal CL size and P4 level can increase the success rate of ET.

Effect of oestrus synchronisation through ovulation delay by vaccination against foot-and-mouth disease in Hanwoo (Bos taurus coreanae) cows.

BACKGROUND: In Korean cattle, after foot-and-mouth disease (FMD) vaccination, anovulation increases, acute immune response is stimulated. OBJECTIVE: Here, we aimed to improve the fertility rate by ovulation delay caused by the foot-and-mouth disease vaccine. METHODS: 160 cows (control, FMD, FMD+Gn250 and FMD+Gn500 groups, with 40 cows each) were used. We analysed the ovulation delay, ovulation rate, conception rate and acute-phase immune responses. RESULTS: In the group vaccinated only with FMD, the average follicle size was maintained at 12 mm and ovulation was delayed. The ovulation rate of the FMD+Gn500 group (500 µg gonadotropin-releasing hormone (GnRH) injections 3 days after the FMD vaccination) was the highest at 81.8%. The ovulation rate of the FMD+Gn250 group (250 µg GnRH injections 3 days after FMD vaccination) was 54.5%, and that of the control group (not FMD vaccinated) was 53.3%. The conception rate was 52.5% (19/40) in the control group, 37.5% (15/40) in the FMD+Gn250 group, and 67.5% (27/40) in the FMD+Gn500 group. Analysis of acute-phase immune response revealed that the plasma contents of haptoglobin and serum amyloid A increased up to 7 days after vaccination against FMD in all the experimental groups, except the control group. CONCLUSIONS: We concluded that ovulation delay can be employed to improve conception rate after FMD vaccination through a modified ovulation synchronisation method with GnRH.

A Machine Learning Approach Reveals a Microbiota Signature for Infection with Mycobacterium avium subsp. paratuberculosis in Cattle.

Although Mycobacterium avium subsp. paratuberculosis (MAP) has threatened public health and the livestock industry, the current diagnostic tools (e.g., fecal PCR and enzyme-linked immunosorbent assay [ELISA]) for MAP infection have some limitations, such as inconsistent results due to intermittent bacterial shedding or low sensitivity during the early stage of infection. Therefore, this study aimed to develop a novel biomarker focusing on elucidating the gut microbial signature of MAP-positive ruminants, since the clinical signs of MAP infection are closely related to dysbiosis. 16S rRNA-based gut microbial community analysis revealed both a decrease in microbial diversity and the emergence of several distinct taxa following MAP infection. To determine the discriminant taxa diagnostic of MAP infection, machine learning-based feature selection and predictive model construction were applied to taxon abundance data or their transformed derivatives. The selected taxa, such as Clostridioides (formerly Clostridium) difficile, were used to build models using a support vector machine, linear support vector classification, k-nearest neighbor, and random forest with 10-fold cross-validation. The receiver operating characteristic-area under the curve (ROC-AUC) analysis of the models revealed their high accuracy, up to approximately 96%. Collectively, taxonomic signatures of cattle gut microbiotas according to MAP infection status could be identified by feature selection tools and applied to establish a predictive model for the infection state. IMPORTANCE Due to the limitations, such as intermittent bacterial shedding or poor sensitivity, of the current diagnostic tools for Johne's disease, novel biomarkers are urgently needed to aid control of the disease. Here, we explored the fecal microbiota of Johne's disease-affected cattle and tried to discover distinct microbial characteristics which have the potential to be novel noninvasive biomarkers. Through 16S rRNA sequencing and machine learning approaches, a dozen taxa were selected as taxonomic signatures to discriminate the disease state. In addition, when constructing predictive models using relative abundance data of the corresponding taxa, the models showed high accuracy for classification, even including animals with subclinical infection. Thus, our study suggested novel noninvasive microbiological biomarkers that are robustly expressed regardless of subclinical infection and the applicability of machine learning for diagnosis of Johne's disease.

Comparison of the bovine blood gas parameters produced with three types of portable blood gas analyzers.

BACKGROUND: A definite diagnosis should be made in the bovine practice field, however, it was difficult to perform laboratory analysis immediately. Currently, three types of portable blood gas analyzers are available in Korea. OBJECTIVES: This study aimed to evaluate the correlations among these three analyzers. METHODS: Seventy-two plasma samples from Holstein-Friesian cows were used for blood gas analysis, and three instruments (EDAN i15 Vet, VETSCAN i-STAT, and EPOC) were operated simultaneously. Moreover, plasma calcium levels were compared between these portable analyzers and blood chemistry device, which is usually used in a laboratory environment. Pearson analysis was performed to confirm the correlation of each parameter produced with the three instruments and blood chemistry analyzer. RESULTS: As results, high correlation was observed in parameters of pH, pO2, potassium ion, ionized calcium, and glucose (p < 0.001, r > 0.7). In addition, pCO2 showed a moderate correlation among the three analyzers (p < 0.001, r > 0.5), and there was no correlation among all instruments for sodium ions. There was also a high correlation between ionized calcium from the three portable devices and total calcium from the biochemistry analyzer (p < 0.001, r > 0.9). CONCLUSIONS: In conclusion, there was a high correlation between results from the three different blood gas analyzers used in the bovine clinical field in Korea. Thus, a consistent diagnosis can be made even with different equipment if the operator is aware of the strengths and weaknesses of each piece of equipment and operates it properly.

Vitamin A supplementation downregulates ADH1C and ALDH1A1 mRNA expression in weaned beef calves.

Our previous studies demonstrated that oral vitamin A supplementation during late-stage pregnancy and the neonatal stage enhances birth weight, growth performance, and mRNA expression related to muscle and preadipocyte development in beef cattle. The alcohol dehydrogenase 1C (ADH1C) c.-64T > C genotype also correlated with vitamin A concentration in beef production. This study aimed to investigate the effects of vitamin A supplementation on the muscle development and vitamin A metabolism in weaned beef calves with different ADH1C genotypes. Twenty male calves (90 d of age; initial BW: 89.03 kg [SD 8.60]) were stratified according to ADH1C genotype and vitamin A treatment (duration: 3 months) and randomly assigned to 4 groups with a 2 × 2 factorial arrangement. Vitamin A treatments included the following: control (10,000 IU/kg of as-fed, a. TT type; b. TC type); treatment (40,000 IU/kg of as-fed, c. TT type; and d. TC type). Parameters including BW, FI, blood, longissimus dorsi muscle, and liver status during the experimental period were analyzed using the generalized linear model (GLM) procedure and Tukey's test by SAS 9.4 program. Serum vitamin A was significantly increased (P < 0.05) in the vitamin A treatment group at 4 and 6 months of age. TT type calves showed higher serum vitamin A concentration (P < 0.05) than the TC type calves. Serum triglyceride and non-esterified fatty acid (NEFA) levels increased (P < 0.05) in the treatment group compared with the control at 6 months of age. However, BW, ADG and FI showed no differences between the groups. In addition, mRNA expression in longissimus dorsi muscle revealed upregulation of paired box 7 (PAX7) (P < 0.05) after the vitamin A treatment period based on biopsy results. Both ADH1C and aldehyde dehydrogenase (ALDH) 1A1 mRNA expression was downregulated (P < 0.01) by vitamin A supplementation. The TC type of ADH1C showed higher mRNA expression than the TT type. However, no effect was observed on adipogenic mRNA expression (preadipocyte factor-1 [PREF-1], peroxisome proliferator-activated receptor gamma [PPARγ], fatty acid binding protein 4 [FABP4]) in all groups. Our findings suggest that weaned calves treated with vitamin A may promote the storage of satellite cells by elevating PAX7 gene expression in the muscle. The TC type calves may show increased capacity for vitamin A metabolism, which can be used in genetically customizing feed management to maximize beef production in the calves.

Increased Ruminoreticular Temperature and Body Activity after Foot-and-Mouth Vaccination in Pregnant Hanwoo (Bos taurus coreanae) Cows.

How does vaccination against foot-and-mouth disease (FMD) affect pregnant cows? Vaccination is the most effective method of preventing the spread of FMD, but it is linked to sporadic side effects, such as abortion and premature birth, which result in economic loss. In this study, ruminoreticular temperature and body activity were measured before and after FMD vaccination using a ruminoreticular biocapsule sensor in Hanwoo cows at different stages of pregnancy. Compared to the unvaccinated groups, the ruminoreticular temperature increased 12 h after vaccination in the vaccinated groups. This increase in temperature is significantly correlated to vaccination. Compared to the nonpregnant and early pregnancy groups, the ruminoreticular temperature of the late pregnancy group increased sharply by more than 40 °C. Moreover, in nonpregnant and early pregnancy groups, a rapid increase in body activity was observed after FMD vaccinations. Of the 73 pregnant vaccinated cows in the study, a total of five cases had side effects (four abortions and one premature birth). Therefore, changes in the ruminoreticular temperature and activity in pregnant cows can be used as raw data to further clarify the association of FMD vaccination with the loss of a fetus and possibly predict abortion, miscarriage, and premature birth following FMD vaccination.

Comparative genomics of bovine mastitis-origin Staphylococcus aureus strains classified into prevalent human genotypes.

Humans may serve as a reservoir host of Staphylococcus aureus, resulting in transmission to animals. Previously, we used RNA polymerase beta subunit gene (rpoB)-based genotyping and classified S. aureus strains into rpoB sequence types (RSTs). According to our previous work, the predominant genotypes of S. aureus in humans and cows differ in Korea, but some predominant genotypes (RST4-1 and RST2-1) in humans have been isolated from bovine mastitis. Therefore, it needs to be determined whether some strains of the predominant human genotypes have adapted to or caused occasional infections in cows. We determined the whole genome sequences of 2 bovine mastitis-origin strains, PMB179 (RST4-1) and PMB196 (RST2-1), and performed comparative genomics with the corresponding RST4-1 and RST2-1 S. aureus strains in the NCBI database. We identified 257 and 180 pseudogenes among 131 RST4-1 and 54 RST2-1 strains, respectively, for the comparison of pseudogene profiles. RST4-1 strains shared more common pseudogenes than RST2-1 strains, and some epidemiologically related strains shared common pseudogenes. However, most of the pseudogenes were strain-specific, and diverse pseudogene profiles were apparent in both the RST4-1 and RST2-1 strains. Furthermore, analysis of the mobile genetic elements, virulence genes, and antibiotic resistance genes revealed no molecular markers to differentiate PMB179 and PMB196 from human strains. Interestingly, the collective comparison of RST4-1 or RST2-1 strains revealed cumulative acquisition steps of genomic islands and antibiotic resistance genes. In conclusion, our data support PMB179 and PMB196 causing occasional infections that result in bovine mastitis.

Spontaneous Alteration of Blood pH By a Bicarbonate Buffer System During Experimental Hypercalcaemia in Cows.

INTRODUCTION: Maintaining mineral homeostasis as well as the secretion and metabolism of mineralotropic hormones is important for healthy of periparturient dairy cows. To increase the activity of mineralotropic hormones, blood pH can be adjusted. The purpose of this study was to investigate changes in blood pH and the mechanism of action of this change in induced hypercalcaemic cows. MATERIAL AND METHODS: Six non-lactating Holstein cows were used in a 2 × 2 crossover design. To induce hypercalcaemia, calcium borogluconate was administered subcutaneously to experimental cows and normal saline was administered subcutaneously to control cows. Blood and urine samples were collected serially after administration. Whole blood without any anticoagulant was processed with a portable blood gas analyser. Plasma concentration and urinary excretion of calcium were measured. RESULTS: In hypercalcaemic cows, both blood and urine calcium levels were significantly increased at 8 h compared to those at 0 h (P < 0.05), and a spontaneous increase in blood pH was also observed. The calcium concentration in plasma was highest at 2 h after administration (3.02 ± 0.27 mmol/L). The change in pH correlated with that in bicarbonate (r = 0.781, P < 0.001) rather than that in partial pressure of CO2 (r = 0.085, P = 0.424). CONCLUSION: Hypercalcaemia induced a spontaneous change in blood pH through the bicarbonate buffer system and this system may be a maintainer of calcium homeostasis.

Evaluation of ruminal motility using an indwelling 3-axis accelerometer in the reticulum in cattle.

Attempts to increase production and improve farm environments have been made for several years. Rumen motility (RM) is one of the biological parameters that provides essential information of individuals in ruminants, and it is usually evaluated by auscultation. The study was aimed to examine RM using the 3-axis accelerometer (3XA) in cattle. The manufactured 3XA were placed in the reticulum (3XA-R) and implanted in the subcutaneous layer of the brisket (3XA-SC), respectively, and the accelerations were compared following intramuscular injection of xylazine (0.05 mg/kg) or saline in experiment 1 and of xylazine (0.05 mg/kg) or atropine (0.04 mg/kg) in experiment 2. In experiment 3, the dose-dependent decrease of RM was evaluated following xylazine administration (0, 0.05, 0.1 mg/kg) in the 3XA-R equipped cows via a 3 × 3 Latin square method. In experiment 1, saline-treated animals showed a continuous fluctuation while the frequency and amplitude of 3XA-R in xylazine-injected cows were reduced after administration. The acceleration of 3XA-SC was changed after administration, but not abruptly. Among the motion parameters, V2 was calculated only using X- and Z-axis acceleration in consideration of the cylindrical shape, and it showed the apparent difference between pre- and post-xylazine administration. In experiment 2, the V2 of 3XA-R was decreased after atropine administration while that of 3XA-SC was maintained. In experiment 3, a dose-dependent V2 decrement of 3XA-R after xylazine administration was observed and lasted for 40 and 80 min in doses of 0.05 mg/kg and 0.1 mg/kg, respectively. In conclusion, The 3XA detected the decrease in RM efficiently and processed the data wirelessly without interference from body movement. This technology will help detect problems early and prevent a decline in cattle productivity.

Changes in plasma pH and blood and urinary macromineral concentrations in experimentally induced hypocalcemic cows with Na2EDTA.

This study was performed to confirm the alterations of blood and urine parameters in artificially induced hypocalcemic cows. For a 2 × 2 cross-over design, four non-pregnant, non-lactating Holstein Friesian cows (623 ± 63 kg) were utilized. Cows in the treatment and control group were infused with ethylenediaminetetraacetic acid (Na2EDTA) solution and normal saline through an intravenous catheter for 3 hr, respectively. Laboratory analyses included complete blood cell count, plasma chemistry, blood gas analysis and urine chemistry. During the hypocalcemic period, abnormal signs were not observed clinically, hematologically nor biochemically either in groups. But, plasma calcium and magnesium concentrations continued to decrease throughout Na2EDTA infusion, and significant group differences (P<0.05 or P<0.001) were detected until 5 hr after the initiation of infusion. Urinary excretions of these minerals were significantly reduced compared to the control group by 6 hr (Ca, P<0.05; Mg, P<0.001). Moreover, there is a significant group difference in the change in plasma pH at 1 hr after Na2EDTA infusion (P<0.05) and maintained a decreased level until 6 hr. Consequently, the blood pH was diminished simultaneously with hypocalcemia and hypomagnesemia induction in cows infused with Na2EDTA. This phenomenon may be one of the mechanisms to recover normocalcemia including maximizing the effect of parathyroid hormone, however, further studies are needed to elucidate the mechanism to alter the blood pH in hypocalcemia.

Evolution of a major bovine mastitic genotype (rpoB sequence type 10-2) of Staphylococcus aureus in cows.

Staphylococcus aureus is the major pathogen leading to bovine mastitis globally while livestock-associated methicillin resistant S. aureus (LA-MRSA) has become a potential threat to public health. MRSA from bovine mastitis is not common but a methicillin susceptible S. aureus (MSSA) genotype, rpoB sequence type (RST)10-2 (RST10-2), is prevalent in Korea. To date, many genomic sequences from S. aureus have been elucidated, but the complete genome sequences of RST10-2 MSSA from bovine mastitis has never been reported. In this study, we determined the complete genome sequence of two RST10-2 MSSA that differ from each other in staphylococcal protein A and molecular prophage types [PMB64-1 (t2489/ mPPT0) and PMB81-4 (t127/mPPT1-2-3)] and conducted a comparative genomics study. The genomic sequences of PMB64-1 and PMB81-4 were more homologous to the representative human RST10-2 strains (MSSA476, MW2 etc.) compared to other RSTs. Most of them shared five common pseudogenes, along with high amino acid identity of four variable virulence genes that were identified in this study. However, PMB64-1 and PMB81-4 acquired different strainspecific pseudogenes and mobile genetic elements than the human strains. The unique pseudogene profile and high identity of the virulence genes were verified in RST10-2 field strains from bovine mastitis. Thus, bovine mastitic RST10-2 MSSA may have an evolutionary relationship with the human RST10-2 community-associated (CA) MSSA and CA-MRSA strains but may have adapted to cows.

Molecular prophage typing of Staphylococcus aureus isolates from bovine mastitis.

Staphylococcus aureus is one of the major pathogens causing bovine mastitis and foodborne diseases associated with dairy products. To determine the genetic relationships between human and bovine or bovine isolates of S. aureus, various molecular methods have been used. Previously we developed an rpoB sequence typing (RSTing) method for molecular differentiation of S. aureus isolates and identification of RpoB-related antibiotic resistance. In this study, we performed spa typing and RSTing with 84 isolates from mastitic cows (22 farms, 72 cows, and 84 udders) and developed a molecular prophage typing (mPPTing) method for molecular epidemiological analysis of bovine mastitis. To compare the results, human isolates from patients (n = 14) and GenBank (n = 166) were used for real and in silico RSTing and mPPTing, respectively. Based on the results, RST10-2 and RST4-1 were the most common rpoB sequence types (RSTs) in cows and humans, respectively, and most isolates from cows and humans clearly differed. Antibiotic resistance-related RSTs were not detected in the cow isolates. A single dominant prophage type and gradual evolution through prophage acquisition were apparent in most of the tested farms. Thus, RSTing and mPPTing are informative, simple, and economic methods for molecular epidemiological analysis of S. aureus infections.

Ruminal methane emissions, metabolic, and microbial profile of Holstein steers fed forage and concentrate, separately or as a total mixed ration.

Few studies have examined the effects of feeding total mixed ration (TMR) versus roughage and concentrate separately (SF) on ruminant methane production. Therefore, this study compared differences in methane production, ruminal characteristics, total tract digestibility of nutrients, and rumen microbiome between the two feeding methods in Holstein steers. A total six Holstein steers of initial bodyweights 540 ± 34 kg were divided into two groups and assigned to a same experimental diet with two different feeding systems (TMR or SF) in a crossover design with 21 d periods. The experimental diet contained 73% concentrate and 27% forage and were fed twice a day. The total tract digestibility of crude protein, neutral detergent fibre, and organic matter were not affected by the two different feeding systems. Steers fed TMR emitted more methane (138.5 vs. 118.2 L/d; P < 0.05) and lost more gross energy as methane energy (4.0 vs. 3.5% gross energy intake; P = 0.005) compared to those fed SF. Steers fed TMR had greater (P < 0.05) total volatile fatty acid (VFA), ammonia-N concentrations and propionate proportion of total VFA at 1.5 h, whereas lower after that compared to steers fed SF. The greater (P < 0.05) acetate: propionate ratio at 4.5 h for steers fed TMR reflected the shift of H2 sink from propionate towards acetate synthesis. The lower (P < 0.05) isobutyrate and isovalerate proportions of total VFA observed in steers fed TMR implies decrease in net consumption of H2 for microbial protein synthesis compared to SF. There were no differences in both major bacterial and archaeal diversity between TMR and SF, unlike several minor bacterial abundances. The minor groups such as Coprococcus, Succiniclasticum, Butyrivibrio, and Succinivibrio were associated with the changes in ruminal VFA profiles or methanogenesis indirectly. Overall, these results indicate that SF reduces methane emissions from ruminants and increases propionate proportion of total VFA without affecting total tract digestion compared to TMR. There were no evidences that the response differed due to different major underlying microbial population.

Prepubertal growth and single nucleotide polymorphism analysis of the growth hormone gene of low birth weight Holstein calves.

Holstein calves weighing less than 20 kg at birth have been noted in Korea. Due to insufficient information, we raised small calves with age-matched normal birth weight Holstein calves and determined body weights before puberty. In addition, 3 single nucleotide polymorphisms (SNPs) of the growth hormone (GH) gene were analyzed. Up to 10 months of age, low birth weight calves were smaller than normal weight calves. In exon 5 of the GH gene, SNP genotype variation was detected in some small calves; however, this did not appear to be the only factor inducing low birth weight and slow growth.

Prevalence, virulence potential, and pulsed-field gel electrophoresis profiling of Shiga toxin-producing Escherichia coli strains from cattle.

BACKGROUND: As a primary source of Shiga-toxin-producing Escherichia coli (STEC) infection, cattle are often targeted to develop strategies for reducing STEC contamination. Monitoring the virulence potentials of STEC isolates from cattle is important for tracing contamination sources, managing outbreaks or sporadic cases, and reducing the risks for human infection. This study aimed to investigate the prevalence of STEC in cattle farm samples in South Korea and to assess their virulence potentials. RESULTS: In total, 63 STEC were isolated from 496 cattle farm samples, and temperature and rainfall affected STEC prevalence (p < 0.001). The O157 serogroup was most prevalent, followed by O108, O8, O84, O15, and O119. In the stx variant test, high prevalence of stx2a and stx2c (known to be associated with high STEC virulence) were observed, and stx2g, a bovine STEC variant, was detected in STEC O15 and O109. Additionally, stx1c was detected in eae-positive STEC, suggesting genetic dynamics among the virulence genes in the STEC isolates. STEC non-O157 strains were resistant to tetracycline (17.9%), ampicillin (14.3%), and cefotaxime (3.6%), while STEC O157 was susceptible to all tested antimicrobials, except cefotaxime. The antimicrobial resistance genes, blaTEM (17.5%), tetB (6.3%), and tetC (4.8%), were only detected in STEC non-O157, whereas tetE (54.0%) was detected in STEC O157. AmpC was detected in all STEC isolates. Clustering was performed based on the virulence gene profiles, which grouped STEC O84, O108, O111, and O157 together as potentially pathogenic STEC strains. Finally, PFGE suggested the presence of a prototype STEC that continues to evolve by genetic mutation and causes within- and between-farm transmission within the Gyeonggi province. CONCLUSIONS: Considerable numbers of STEC non-O157 were isolated from cattle farms, and the virulence and antimicrobial resistance features were different between the STEC O157 and non-O157 strains. STEC from cattle with virulence or antimicrobial resistance genes might represent a threat to public health and therefore, continual surveillance of both STEC O157 and non-O157 would be beneficial for controlling and preventing STEC-related illness.

A novel technique of ultrasound-guided brachial plexus block in calves.

An interventional ultrasound technique to increase the safety of surgical treatment of the calf forelimb was tested. First, the brachial plexus was evaluated using ultrasonography and then 2% lidocaine was injected under ultrasound guidance. Ultrasonically, the brachial plexus appeared as multiple hypoechoic areas surrounded by a hyperechoic rim or a hyperechoic structure characterised by multiple discontinuous lines. It was located between the omotransverse muscle and axillary artery and vein. The sensitive effect in the forelimb was seen mainly in the area supplied by the musculocutaneous nerve, indicating successful blockage in the nerve plexus. Out of the eight forelimbs, the motor effect was observed in seven forelimbs. These results suggest the clinical feasibility of ultrasound-guided brachial plexus block in bovine medicine, although further studies are needed to examine various approaches, including the sites of needle insertion and the appropriate volume and dosage of anaesthetic.