Dairy Cows In China Research Articles

The Genetic Characteristics of FT-MIRS-Predicted Milk Fatty Acids in Chinese Holstein Cows

Fourier Transform Mid-Infrared Spectroscopy (FT-MIRS) can be used for quantitative detection of milk components. Here, milk samples of 458 Chinese Holstein cows from 11 provinces in China were collected and we established a total of 22 quantitative prediction models in milk fatty acids by FT-MIRS. The coefficient of determination of the validation set ranged from 0.59 (C18:0) to 0.76 (C4:0). The models were adopted to predict the milk fatty acids from 2138 cows and a new high-throughput computing software HiBLUP was employed to construct a multi-trait model to estimate and analyze genetic parameters in dairy cows. Finally, genome-wide association analysis was performed and seven novel SNPs significantly associated with fatty acid content were selected, investigated, and verified with the FarmCPU method, which stands for “Fixed and random model Circulating Probability Unification”. The findings of this study lay a foundation and offer technical support for the study of fatty acid trait breeding and the screening and grouping of characteristic dairy cows in China with rich, high-quality fatty acids. It is hoped that in the future, the method established in this study will be able to screen milk sources rich in high-quality fatty acids.

Molecular and epidemiological characterization of Staphylococcus aureus causing bovine mastitis in China

BackgroundStaphylococcus aureus is one of the most prevalent pathogens in bovine mastitis, which leads to substantial financial losses for the dairy industry. ResultsIn this study, S. aureus (n = 72) was isolated from 18 dairy farms in 15 provinces across China in 2021. The identification of these isolates at the species level was achieved by employing 16S rRNA sequencing. An isothermal amplification method for auxiliary detection of S. aureus was established, which can be employed not only for laboratory detection but also for point-of-care testing (POCT). Molecular characteristics of S. aureus mastitis in Chinese dairy cows were determined through MLST and spa typing. Finally, methicillin-resistant Staphylococcus aureus (MRSA) and MRSA resistance genes were detected using MIC and PCR amplification techniques. 72 isolates were identified as 12 sequence types (STs) and 7 clonal complexes (CC). ST1/CC1 was the dominant prevalent accounting for 33.3 % of the total, and exhibiting a wide distribution range. In terms of spa types, t114 was the dominant type, accounting for 31.9 % of the total, followed by t529 as the second major type. Four S. aureus strains were classified as MRSA according to their levels of oxacillin resistance (MIC ≥4 μg/mL). Among these four MRSA strains, one of them was found to be mecA positive. However, the presence of drug-resistance genes mecA and mecC was not detected in the remaining three MRSA strains, indicating the possible existence of new resistance genes. ConclusionsOur study investigated the prevalence of S. aureus mastitis in dairy cows in China, while also examined the molecular characteristics and MRSA strains. This information will help with the clinical monitoring, prevention, and control of S. aureus mastitis in dairy cattle.

Green total factor productivity of dairy cows in China: essential facts from the perspective of regional heterogeneity

Introduction: Enhancing the green total factor productivity of dairy cows (GPDC) is crucial for fostering the low-carbon sustainable development of the dairy industry.Methods: This research utilizes the Minimum distance to weak efficient frontier–Meta frontier–Malmquist–Luenberger (MinDW-MML) index to examine the GPDC using the unbalanced panel data on dairy cows in 26 provinces of China from 2004 to 2020, taking into account regional heterogeneity and unexpected output.Results: The findings revealed that 1) from 2004 to 2020, China’s GPDC displayed a fluctuating and declining trend, with the steepest decrease occurring from 2007 to 2010 (2.26% at the common frontier and 1.81% at the group frontier). The fundamental cause of the low GPDC, as seen from the standpoint of efficiency decomposition, is technical advancement (technological change, or TC); 2) the GPDC exhibits a declining trend from east to west to central China for the two-level frontier. The eastern region benefits clearly from technological advancement (TC) and improved technical performance (EC), while the middle and western regions are mostly constrained by TC; and 3) the GPDC displayed regional heterogeneity at several scales. Although the efficiency values of medium- and small-scale aquaculture were low and large-scale aquaculture GPDC in the eastern and western regions was greater than 1, the GPDC did not reach the effective state in the central region.Discussion: Based on these findings, we propose policy recommendations such as promoting technological innovation and low-carbon technology in dairy farming, improving the technical system of dairy farming, and optimizing the industrial layout of dairy farming, which will serve as a model for future high-quality and sustainable dairy farming development in China, and provide an experience for green dairy farming development in other countries.

Hematology Reference Intervals for Holstein Cows in Southern China: A Study of 786 Subjects.

Simple SummaryThe American Society of Veterinary Clinical Pathology guidelines recommend that hematology reference intervals (RIs) should be established based on specific animals in specific regions. However, the information on hematology RIs is still lacking for Chinese dairy cows, which account for a total number of more than 3 million. Thus, the aim of this study is to establish hematology RIs for Chinese dairy cows using a large sample size. After the collection of blood samples from 786 Holstein cows, we generated hematology RIs according to overall animals, different ages, different parities and different lactation stages. Our results provide important hematologic information for both clinicians and researchers to approach the health surveillance of Holstein cows in southern China.Hematology RIs help clinicians and researchers determine whether a hematology parameter is abnormal, which plays an important role in animal health surveillance. China is one of the largest dairy producers in the world, with millions of Holstein cows. However, there has been no published data on hematology RIs for dairy cows in China yet. Therefore, the aim of this study is to establish updated and accurate RIs for Holstein cows in southern China. To increase the accuracy of the RIs, we collected blood samples from 786 Holstein cows and analyzed 25 hematologic variables. The RIs for Holstein cows were established using the 95% percentile RIs according to the American Society of Veterinary Clinical Pathology guidelines. The effects of different ages, parities and lactation stages were also checked in this study. The data of 21, 22 and 19 out of 25 hematology parameters were significantly different between different ages, parities and lactation stages, respectively. Furthermore, the hematology RIs of separate subclasses according to different ages, parities and lactation stages were generated. Hematology RIs according to ages and lactation stages, as well as parities and lactation stages, were also assessed. Together, our results confirm that hematology RIs for cows vary by ages, parities and lactation stages. The present study helps to fill the gap in hematology RIs for Holstein cows in southern China, and our data may serve as a very useful tool for monitoring the health and welfare of dairy cattle in China.

Evaluation of an ELISA for the diagnosis of bovine tuberculosis using milk samples from dairy cows in China

Bovine tuberculosis (bTB) is an important zoonotic disease in developing countries including China. Lack of rapid and simple detection methods for surveillance affects efficient control and eradication of this disease. The objective of this study was to determine the feasibility of using an individual and bulk milk sample ELISA based on the fusion protein of four specific antigens (CFP10/ESAT-6/MPB70/MPB83) of Mycobacterium bovis for the rapid detection and surveillance of bTB in dairy cattle herds and to identify individual animal factors that affect its results. The study population consisted of 388 dairy cows from four herds in Henan province, China. The serum sample ELISA (cut-off value 30%) and milk sample ELISA (cut-off value 10%) were shown to have good agreement, while, there was fair agreement between a blood sample IFN-γ in vitro release assay and the milk sample ELISA (cut-off value 10%) (Cohen’s kappa statistic of 0.492 and 0.306, respectively). The sensitivity and specificity for the milk sample ELISA using a S/P% cut-off value of 10%, as estimated using a Bayesian latent class analysis model, was 48.4% (95%CI: 31.0 – 85.2) and 97.1% (95%CI: 92.2 – 99.7), respectively. Although both ELISAs had comparable sensitivities and specificities, the milk sample ELISA had a greater discriminatory ability, as measured by the area under the curve (ROC), than the serum sample ELISA with the difference of their AUCs being − 0.069 (95%PCI: −0.121 to −0.021). Further, it was estimated that the lower limit of detection at an animal level lacto-prevalence might be 1.1% with this milk ELISA using bulk milk samples. Additionally, a mixed linear regression model, incorporating herd as a random effect variable, was constructed to investigate the association between natural log-transformed bTB sample-to-positive ratio (LnS/P%) and milk data. Across the model, natural log-transformed Somatic Cell Count (SCC) and parity had a positive effect on the LnS/P% of bTB antibody response, and milk urea nitrogen had a curvilinear association with LnS/P%. In conclusion, a milk ELISA for bTB antibodies, especially bulk tank milk antibodies, could be used as an efficient tool for rapid screening in surveillance, which might be followed by confirmatory testing with IFN-γ assay in dairy cattle, during the implementation of bTB control programmes. Relevant milk factors should be considered to adjust the S/P% with the aim of classifying the infection status of animals and herds as accurately as possible.

The effects of cow-related factors on rectal temperature, respiration rate, and temperature-humidity index thresholds for lactating cows exposed to heat stress.

The objectives of this study were to investigate the effects of the cow-related factors on rectal temperature (RT) and respiration rate (RR) of lactating dairy cows under different heat stress (HS) conditions and establish the temperature-humidity index (THI) thresholds at which RT and RR begin to increase for cows in China. Cow-related factors included body posture (standing and lying), milk yield (<26kg/d, ≥ 26-39kg/d, and ≥39kg/d), days in milk (≤60d, > 60 and≤150d, and >150d), and parity (1, 2, and ≥3). Records of RT, RR, and individual characteristics were collected from July to October 2020 on a commercial dairy farm in Northern China, where 826 Holstein lactating cows were measured. Using the broken-stick regression models and the entire dataset, the THI thresholds for RT and RR were 69.8 and 67.1, respectively. Therefore, the heat stress conditions during this study were classified according to the THI levels as thermoneutrality (TN, 60<THI≤67), mild (67<THI≤72), moderate (72<THI≤80), and severe (80<THI≤86). Results showed that lying cows exhibited the higher RT and RR but the lower THI threshold for RT (68.8 vs. 70.7) and RR (65.6 vs. 68.4) than standing cows; milk yield is positively associated with the values of RT and RR under TN or HS conditions, and the THI thresholds for RT (70.2 vs. 70.0 vs. 68.0) and RR (68.1 vs. 64.7 vs. 64.7) were progressively lower for low-yielding, middle-yielding, and high-yielding cows; there was a significant increase in RT and RR in early-lactation cows compared to late-lactation cows under TN or HS conditions (P<0.001), and the lowest THI threshold (67.8 for RT and 64.7 for RR) was observed in early-lactation cows, followed by mid-lactation cows (68.2 for RT and 65.3 for RR) and late-lactation cows (70.0 for RT and 67.3 for RR); the effects of parity were not significant on RT (P>0.05), but significant on RR (P<0.001). The THI thresholds for RT (69.2) and RR (66.0) were lowest for cows in 3rd-parity and higher, followed by cows in 2nd-parity (70.0 for RT and 68.9 for RR) and 1st-parity (70.7 for RT and 66.6 for RR). This study highlighted the great significance of considering the cow-related factors in heat stress responses and THI threshold assessment. For dairy cows in China, we suggest that cooling should be initiated when THI reaches 65 to 66.

Review: Challenges and prospects for milk production in China after the 2008 milk scandal

The primary objectives of this review were to characterize the challenges faced by China’s milk industry after the milk scandal of 2008 and to propose prospects for the future. This review is supported by data and information from the literature, various statistical yearbooks and databases, administration documents, news reports, and the authors’ own investigations. After the milk scandal and the resulting decline in the number of dairy cows in China, more recently annual milk production has come to the end of a rapid growth period. Importing large quantities of dairy products, especially milk powder, has affected domestic milk production. The high cost of milk production in China is the key reason for the lack of market competitiveness for milk within the country. Dairy farms are facing stricter environmental protection requirements, which have become an important economic constraint for future dairy farming development. In the transition from small-scale to large-scale (100 or more cows per farm) dairy farms in China, more 10,000-cow farms have emerged, which has triggered a debate about the size of dairy farms. Although China’s milk production is facing some challenges, the continuous improvement of consumers’ income, the formation of milk drinking habits, and governmental support have developed a large market potential for domestically produced dairy products and milk production. Improving market competitiveness while ensuring economic and environmental sustainability are key to the future prospects for China’s milk industry. The characterization and discussion of the past, current, and potential dairy industry in China is intended to enhance understanding for dairy farmers, dairy enterprises, and the government to positively and significantly adjust the strategies for the dairy industry. Future research needs to address the effects of different organizational forms of dairy enterprises and dairy farmers on milk production in China.

Using vaginal discharge score (VDS) grading system to evaluate the effect of clinical endometritis on reproductive performance of dairy cows in China.

Clinical endometritis (CE) is a major cause in affecting the reproductive performance of dairy cows. The objectives of this study were to ascertain the prevalence of CE and to evaluate the effect of CE on reproductive performance in dairy cows using vaginal discharge score (VDS) grading system. 803 dairy cows were examined by vaginoscope with 4-point VDS at 26 ± 3 days in milk (DIM) and classified into six groups: non-endometritis with VDS 0 (control; CON), endometritis with VDS 1 (MEM), non-treated endometritis with VDS 2 (NTME), treated endometritis with VDS 2 (TME), non-treated endometritis with VDS 3 (NTPE), and treated endometritis with VDS 3 (TPE). Cows in TME and TPE groups were treated with 200 mL of 50% dextrose solution by intrauterine infusion. The prevalence of CE was 33% at 26 ± 3 DIM. Binary logistic regression analysis revealed cows in MEM, NTME and NTPE groups had a less likelihood of first artificial insemination (AI) pregnancy than those in CON group (P < 0.05). Kaplan-Meier survival curves for days open were statistically different (P = 0.004). In Cox regression model, cows in NTME and NTPE groups had a reduced pregnancy rate than those in CON group (P < 0.05). The hazard of pregnancy in NTME group was lower than that in TME group (P = 0.044). Similarly, it was lower for the hazard of pregnancy in NTPE group than in TPE group (P = 0.048). Cows in MEM, NTME, and NTPE groups required more services per pregnancy than those in CON group (P < 0.05). In conclusion, CE examined by the VDS grading system impaired reproductive performance, and mild endometritis with VDS 1 should be treated in the early postpartum period to ameliorate fertility in dairy herds.

Spatio-Temporal Dynamics of Feed Grain Demand of Dairy Cows in China

As the income of urban and rural residents has increased in recent decades in China, dairy products have become an important part of the Chinese diet. Therefore, keeping up with the growing demand for feed grain for dairy cows is a critical issue of feed grain security. Utilizing traditional statistical and spatial statistical methods, this study analyzes the spatio-temporal dynamics of dairy cow feed grain (DCFG) demand on the provincial, regional, and national levels across China from 1990 to 2016. Additionally, this paper explores the impacts of various factors on the spatio-temporal dynamics of DCFG demand using the Geo-Detector method. The results demonstrate that: (1) the temporal dynamics of DCFG demand can be divided into three stages of slow growth, rapid growth, and high-level stability, and the relative level of DCFG demand in the whole animal husbandry tends to decline; (2) at the regional and national levels, the spatial concentration of high DCFG demand has intensified; in particular, North China was the region where the largest demand for DCFG was localized and was increasing at the highest rate; (3) based on the hot spot analysis of provincial DCFG demand, the high and low demand provinces of DCFG have sharp characteristic contrast from north to south China; (4) the spatio-temporal dynamics of DCFG demand in China were essentially co-affected by the four groups of factors (e.g., resource endowment, feeding scale, feeding technology, and market environment), of which resource endowment and feeding scale were the dominant factors. Therefore, in the future, dairy cow feeding in China should promote grain-saving feeding technology, improve the utilization of forage, expand large-scale feeding, and create a good market environment to ensure the reasonable development and sustainability of DCFG demand.

Detection and molecular characteristics of neboviruses in dairy cows in China.

In this study, 98 diarrhoeic and 70 non-diarrhoeic samples were collected from 13 dairy farms located across 5 provinces in China from April 2017 to May 2018. Approximately 41.8 % (41/98) of diarrhoeic samples and 5.7 % (4/70) of non-diarrhoeic samples were nebovirus-positive based on RT-PCR results, and some diarrhoeic samples were co-infected with bovine rotavirus (73.2 %), bovine coronavirus (36.6 %) and/or bovine viral diarrhoea virus (31.7 %). A phylogenetic analysis of 23 nebovirus RdRp fragments showed that these strains were closely related to Nebraska-like (NB-like) strains but were all located in a unique large branch. Moreover, a phylogenetic analysis of the 18 complete VP1 sequences from this study revealed that 14 strains belonged to lineage 1 and 4 strains belonged to lineage 3. Notably, all four lineage 3 strains shared the same recombination event, with a breakpoint located within the P1A domain. The complete genome of one nebovirus strain, Bo/YLA-2/17/CH, which had a recombination event within the P1A domain of its VP1, was successfully sequenced and was found to be 7453 nt in length, and this may represent a novel nebovirus strain based on the phylogenetic analysis of its complete genome sequence. In conclusion, this study reveals that neboviruses circulate widely in dairy cows in China and exhibit a unique evolution of RdRp. To the best of our knowledge, this is the first reported recombination event located within the P1A domain of nebovirus VP1.

Absence of zoonotic hepatitis E virus infection in Flemish dairy cows

Recently, infectious HEV particles were discovered in milk and fecal samples of dairy cows in China. Given the recent increase of autochthonous HEV infections in Europe, we wanted to assess whether cows constitute an HEV reservoir in this region and hence may be responsible for the advance of HEV through consumption of cow produce. To verify the zoonotic risk cows potentially pose towards European consumers, we screened >10% of dairy milk farms in Flanders, Belgium for the presence of HEV. A quarter of these housed both cows and pigs, the latter a well-known reservoir for HEV. Milk and fecal samples were analyzed for the presence of HEV RNA and HEV-specific antibodies.Despite the fact that HEV is circulating amongst pig farms in Flanders and proof of active HEV infection in the pigs of at least one of the mixed farms included in our study, we could not detect any sign of active or past HEV infection in cows. The HEV prevalence in our study was 0%, with a 99.99% confidence interval (CI) for HEV RNA and anti-HEV antibody of [0%–2.30%] and [0%–4.23%] respectively. Our results suggest that, at least in Flanders, cows are not an HEV reservoir and hence do not pose a major health risk towards humans.

Performance Evaluation of Manure Nitrogen Output Models Suitable for Lactating Dairy Cows in China

Abstract. Manure nitrogen (N) output from dairy cattle is a major environmental concern in China. Various empirical models are available to predict manure N output from dairy cattle, but the accuracy and precision of these models has not been assessed for Chinese conditions. The objective of this study was to evaluate the performance of extant models that predict different forms of manure N output for lactating dairy cows in China with the aim of identifying the best-fit and most suitable prediction models. A total of 35 empirical models were evaluated for their ability to predict N excretion of dairy cows in China fed a wide range of diets. The data set consisted of 99 treatment means from 32 publications with information on animal and dietary characteristics and N output flows. Performance of the models was evaluated using root mean square prediction error (RMSPE) and concordance correlation coefficient (CCC) analysis. A model (eq. 19) based on N intake (NI) was selected as best for predicting fecal N excretion (RMSPE = 15.8% and CCC = 0.75). Another model that also used NI as an input variable was most suitable for predicting urinary N (RMSPE = 26.0% and CCC = 0.63, eq. 14) and total N (RMSPE = 15.8% and CCC = 0.81, eq. 31). Models predicting urinary urea N (UUN) and urinary N / total N performed poorly. Overall, the deviation of the regression line from the equality line (y = x line) for even the best-fit urinary, fecal, and total N excretion models demonstrated the need to develop improved models for use under Chinese conditions. Using N output data from dairy cows in China to develop manure N output models may help improve environmental stewardship of the dairy industry in China. Keywords: Dairy cows, Evaluation, Manures, Model performance, Nitrogen excretion.

Early Warning System of Risk in Dairy Cows with Inactive Ovaries

The incidence of Inactive ovaries of dairy cows in China is relatively high. There is no complete early warning system for the occurrence of ovarian quiescence in clinical cows. This test provides early warning indicators for clinical prediction of ovary cessation in dairy cows. This experiment selected blood samples of dairy cows from 60 to 90 days postpartum in the inactive ovaries group and control group. Differential proteins were selected on the basis of proteomics, three energy indexes: AST, Glu, NEFA. Four reproductive hormones: E2, P4, FSH, LH, and four differentially expressed proteins: IGFBP-2, AHSG, APO-A4, and RBP-4. Key enzyme activities: ALDOB, LDHB, ITIH3, GPX3, SPAM1, PKM2. The ELISA test kit was used to detect the content and activity of the above markers in the test bovine serum. Through correlation analysis, binary logistic regression modeling and ROC analysis, a single indicator early warning technique for APOA4 and ITIH3 was established. The early warning values were APOA4 > 28.825 μg/L and ITIH3 > 195.07 ng/L. A multi-index early warning system based on potential biomarkers of APOA4 + ITIH3 and APOA4 + ITIH3 + E2 was established. The former had an early warning value of: APOA4 > 19.55 μg/I; ITIH3 > 191.14 ng/L; the latter has an early warning value: APOA4 > 47.56 μg/L, ITIH4 > 187.80 ng/L, E2 < 69.63 ng/L.

Heat stress alleviation for dairy cows housed in an open-sided barn by cooling fan and perforated air ducting (PAD) system

Curtain-sided barns with circulation fans above stall are commonly used to house dairy cows in China. Many farms equipped with circulation fans are unable to provide appropriate cooling, especially for the naturally ventilated shed, which can result in decreasing feed intake and milk production. For alleviating heat stress and improving animal comfort, a system consisting of an air cooler and a 30 m perforated air duct (PAD) was integrated to evenly distribute cooling air. The air was cooled by underground water and delivered to targeted zones above stall bed. The system was evaluated in an open sided dairy barn in Tianjin, China. For the stalls equipped with PAD system, air velocity reached above 1.1 m/s at 0.5 m height plane of the stall space, and was more uniformly distributed. Compared to the stalls equipped with circulation fans, the PAD system lowered air temperature by 1.5°C, and increased relative humidity by 8.1%. On average, Temperature Humidity Index (THI) and Equivalent Temperature Index (ETI) were decreased by 0.5 and 0.6, respectively. After a 15 days’ operation of the system, rectal temperatures of the treated dairy cows were significantly lowered. The results also showed that the cows under PADs had a higher milk production. These findings suggest the PAD can be an effective cooling alternative for naturally ventilated dairy barns to alleviate heat stress. Keywords: dairy cow, heat stress, perforated air duct, cooling fan, naturally-ventilated barn DOI: 10.25165/j.ijabe.20171006.3135 Citation: Xie L N, Wang C Y, Ding L Y, Gui Z Y, Zhang L, Shi Z X, et al. Heat stress alleviation for dairy cows housed in an open-sided barn by cooling fan and perforated air ducting (PAD) system. Int J Agric & Biol Eng, 2017; 10(6): 1–10.

Heat stress alleviation for dairy cows housed in an open-sided barn by cooling fan and perforated air ducting (PAD) system

Curtain-sided barns with circulation fans above stall are commonly used to house dairy cows in China. Many farms equipped with circulation fans are unable to provide appropriate cooling, especially for the naturally ventilated shed, which can result in decreasing feed intake and milk production. For alleviating heat stress and improving animal comfort, a system consisting of an air cooler and a 30 m perforated air duct (PAD) was integrated to evenly distribute cooling air. The air was cooled by underground water and delivered to targeted zones above stall bed. The system was evaluated in an open sided dairy barn in Tianjin, China. For the stalls equipped with PAD system, air velocity reached above 1.1 m/s at 0.5 m height plane of the stall space, and was more uniformly distributed. Compared to the stalls equipped with circulation fans, the PAD system lowered air temperature by 1.5°C, and increased relative humidity by 8.1%. On average, Temperature Humidity Index (THI) and Equivalent Temperature Index (ETI) were decreased by 0.5 and 0.6, respectively. After a 15 days’ operation of the system, rectal temperatures of the treated dairy cows were significantly lowered. The results also showed that the cows under PADs had a higher milk production. These findings suggest the PAD can be an effective cooling alternative for naturally ventilated dairy barns to alleviate heat stress. Keywords: dairy cow, heat stress, perforated air duct, cooling fan, naturally-ventilated barn DOI: 10.25165/j.ijabe.20171006.3135 Citation: Xie L N, Wang C Y, Ding L Y, Gui Z Y, Zhang L, Shi Z X, et al. Heat stress alleviation for dairy cows housed in an open-sided barn by cooling fan and perforated air ducting (PAD) system. Int J Agric & Biol Eng, 2017; 10(6): 1–10.

Occurrence and characterization of blaNDM-5-positive Klebsiella pneumoniae isolates from dairy cows in Jiangsu, China.

To investigate the epidemiological characteristics and the surrounding genetic structure of the blaNDM-5 gene in Klebsiella pneumoniae derived from dairy cows in Jiangsu Province, China. Ten carbapenem-resistant K. pneumoniae were collected from three dairy farms and were screened for the presence of carbapenemase genes using PCR and sequencing. PFGE and MLST were conducted to analyse the genetic relatedness of the blaNDM-5-harbouring K. pneumoniae isolates. The location of blaNDM-5 was identified by S1 nuclease-PFGE and Southern blotting. The transferability and profiles of blaNDM-5-carrying plasmids were analysed by conjugation experiments, and PCR-based replicon typing and RFLP, respectively. The surrounding genetic structure of the blaNDM-5 gene was obtained using WGS and PCR mapping. All 10 K. pneumoniae from dairy cows harboured the blaNDM-5 gene, exhibited resistance to multiple antimicrobials and belonged to five STs, of which ST1661 and ST2108 were the most prevalent. The blaNDM-5 gene was located on the ∼46 kb IncX3 plasmid in all isolates and these plasmids could be conjugated to an Escherichia coli recipient with no additional resistance profiles transferred. All blaNDM-5-carrying plasmids shared similar genetic contexts and were nearly identical to that of the human K. pneumoniae plasmid (pNDM-MGR194) previously reported in India. This was the first case of blaNDM-5-positive K. pneumoniae identified from dairy cows in China. The IncX3 pNDM-MGR194-like plasmid disseminated among cow farms should be highlighted and its potential role in mediating transmission of the blaNDM gene between bacteria from humans and animals requires further monitoring.

Effects of Forage Type and Dietary Concentrate to Forage Ratio on Methane Emissions and Rumen Fermentati

<abstract><title><italic>Abstract.</italic></title> This study was conducted to evaluate the effects of dietary forage type and concentrate-to-forage ratio (CTFR) on CH₄ emissions from dairy cows in China using the SF₆ tracer method. Rumen fluid concentrations of NH₄-N and VFA, rumen fluid pH, and daily milk yield were measured as well. The dietary regimens included: corn stalks (dry corn stalks after corn harvest) as the forage source at CTFR of 40:60 (ration A), corn silage as the forage source at CTFR of 40:60 (ration B), and corn silage as the forage source at CTFR of 60:40 (ration C). Twelve dairy cows (body weight = 525 ±12 kg, mean ±SE) were divided into three groups of four animals each, balanced in age and body weight, and randomly allocated to the dietary treatments. The study was run for 25 days, with the first 15 days used for adjustment and the subsequent 10 days used for response measurement. The dietary treatments ranked ration A > ration B > ration C for CH₄ emissions quantity (L d^-1 head^-1), rumen fluid pH, acetic acid concentration, and ratio of acetic acid and propionic acid concentration. For example, CH₄ emissions (mean ±SE) for rations A, B, and C were 353 ±13.4, 283 ±7.48, and 263 ±9.04 L d^-1 head^-1, respectively, or 335 ±12.75, 270 ±7.12, and 250 ±8.6 L d^-1 AU^-1 (AU = 500 kg live weight). On the other hand, the treatments ranked ration A < ration B < ration C for concentrations of NH₃-N, propionic acid, and butyric acid in the rumen fluid. This study indicates that CH₄ emissions intensity from dairy cows (g kg^-1 milk output) can be significantly reduced by using corn silage as a forage source and by increasing the content of concentrates in the ration. Compared with rations B and C, ration A increased CH₄ emissions by 25% and 34% (p < 0.01), respectively. A full assessment of the effectiveness of such an improved feeding management, through life cycle analysis, in reducing carbon footprint would be warranted in future studies.

Survey of mycotic mastitis in dairy cows from Heilongjiang Province, China

A survey of the prevalence rate, pathogenic subspecies, and risk factors of mycotic mastitis in dairy cows from Heilongjiang Province, China, was conducted. Milk samples from 412 cows with chronic mastitis were collected and cultured on 8% sheep blood agar, MacConkey agar, and Sabouraud agar with chloramphenicol. Counting of the morphologically distinct colonies was performed, as well as the isolation and identification of organisms through phenotypical and physiological criteria. Four hundred seventy-eight aerobic microorganisms were isolated. Yeasts and yeast-like fungi 35.6% (170/478) and bacteria 64.4% (308/478) were isolated. The fungal isolates were identified as Candida (79.4%), Trichosporon (5.9%), Aspergillus (7.1%), Cryptococcus (2.4%), and Rhodotorula (4.1%). More than ten species of yeast were isolated including Candida krusei 50/135 (37%), Candida rugosa 16/135 (11.9%), and Candida lusitaniae 15/135 (11.1%). A higher positivity (18.5 and 56.3%) (P ≤0.05) was observed in cows from environmental temperatures of 0-15 and 15-35°C than those at <0°C and in cows affected by the disease for >45 and 30-45days compared with cows suffering 10-30days. Meanwhile, a statistically significant difference (44.9 vs. 31.4%) (P ≤0.05) was observed under extensive raising systems vs. intensive raising systems. It appears that Candida is a major pathogen of mycotic mastitis of dairy cows. Extensive raising system, high environmental temperature (15-35°C), and the duration of the disease (>30days) were important risk factors of the incidence of mycotic mastitis. Here, we provide a theoretical foundation for research into preventing and treating mycotic mastitis of dairy cows in China.

Isolation of Mycobacterium tuberculosis complex (MTBC) from dairy cows in China

Eleven thousand five hundred and eighty non-blood samples from dairy cows were subjected to mycobacterium culture and genotyping. As a result, a total of 142 isolates of Mycobacterium tuberculosis complex (MBTC) were identified. Among them, 65 were Mycobacterium tuberculosis , while 77 Mycobacterium bovis . The genotype of M. tuberculosis strains was mainly Beijing family. In addition, the isolation rates of MTBC were 33.89% for lung lymph nodes, 2.81% for nasal swabs, and 3.95% for pharyngeal swabs from cattle positive to tuberculin skin test, respectively. This evidence implied that M. tuberculosis infection in cattle is a new risk to public health and should be paid more attention. Key words : Mycobacterium tuberculosis complex, cows, tuberculosis, zoonosis.

The detection of “Candidatus Mycoplasma haemobos” in cattle and buffalo in China

"Candidatus Mycoplasma haemobos" is a hemoplasma species found in cattle and has been recently reported in Switzerland and Japan. In this study, "Candidatus Mycoplasma haemobos" was shown to occur in cattle and buffalo in tropical China by PCR amplification and sequence analysis of the 16S rRNA gene from blood samples. Based on the 16S rDNA sequence, a specific PCR assay was developed. Occurrence of "Candidatus Mycoplasma haemobos" in cattle and buffalo in Guangxi, China, was determined by examining 25 buffalo blood samples, 12 yellow cattle blood samples and 42 dairy cow blood samples. The results showed that 32% (8/25) of buffalo, 41.7% (5/12) of yellow cattle, and 14.3% (6/42) of dairy cows were positive for "Candidatus Mycoplasma haemobos", respectively. Direct sequencing of representative PCR products confirmed that the amplified partial 16S rDNA sequence represented "Candidatus Mycoplasma haemobos". This is the first report of "Candidatus Mycoplasma haemobos" in buffalo, yellow cattle, and dairy cows in China.