Dairy Cattle Industry Research Articles

Veterinary Expert Opinion on Potential Drivers and Opportunities for Changing Antimicrobial Usage Practices in Livestock in Denmark, Portugal, and Switzerland.

Reducing antimicrobial use (AMU) in livestock is requested by Public Health authorities. Ideally, this should be achieved without jeopardizing production output or animal health and welfare. Thus, efficient measures must be identified and developed to target drivers of AMU. Veterinarians play a central role in the identification and implementation of such efficient interventions. Sixty-seven veterinarians with expertise in livestock production in Denmark, Portugal, and Switzerland participated in an expert opinion study aimed at investigating experiences and opinions of veterinarians about the driving forces and practices related to AMU in the main livestock sectors (broiler, dairy cattle, fattening/veal calf, and pig industry) of the aforementioned countries. Opinions on potential factors influencing the choice of antimicrobials and opportunities to reduce AMU were collected. Antibiograms are seldom used, mainly due to the time lag between testing and obtaining the results. The perceived percentage of treatment failures varied between countries and livestock sectors; however, little changes were reported over time (2005−2015). The animal health problems of each livestock sector most frequently leading to AMU did not vary substantially between countries. Mandatory official interventions (i.e., binding measures applied by national or international authorities) were highlighted as having the biggest impact on AMU. There was a variation in the experts’ opinion regarding feasibility and impact of interventions both between countries and livestock sectors. Nevertheless, improved biosecurity and education of veterinarians frequently received high scores. Most veterinarians believed that AMU can be reduced. The median potential reduction estimates varied from 1% in Swiss broilers to 50% in Portuguese broilers and veal/fattening calves in all countries. We hypothesize that the differences in views could be related to disease epidemiology, animal husbandry, and socio-economic factors. A profound investigation of these disparities would provide the required knowledge for developing targeted strategies to tackle AMU and consequently resistance development. However, experts also agreed that mandatory official interventions could have the greatest impact on antimicrobial consumption. Furthermore, improvement of biosecurity and education of veterinarians, the use of zinc oxide (in pigs), improving vaccination strategies, and the creation of treatment plans were the measures considered to have the largest potential to reduce AMU. This paper can inform policymakers in Europe and countries with a similar animal production regarding their AMU policy.

Mutual antagonism between Mannheimia haemolytica and Pasteurella multocida when forming a biofilm on bovine bronchial epithelial cells in vitro

Mannheimia haemolytica and Pasteurella multocida are two bacterial species implicated in the bovine respiratory disease complex (BRDC) that is costly to the beef and dairy cattle industries. Both bacterial species are thought to occupy a similar niche as commensals in the upper respiratory tract. Many bacteria are thought to exist as biofilms in their hosts, perhaps in close proximity with other bacterial species. We previously showed that M. haemolytica forms biofilm on bovine respiratory epithelial cells in vitro. We are interested in the possibility that M. haemolytica and P. multocida co-exist as biofilms in the upper respiratory tract of cattle. In this study, we begin to explore this possibility by assessing the ability of M. haemolytica and P. multocida to form a biofilm on bovine respiratory epithelial cells in vitro. We found that M. haemolytica and P. multocida are separately able to form biofilms on bovine respiratory epithelial cells, but mutually inhibit one another when incubated together as a biofilm. Both the biofilm matrix (crystal violet stain) and bacterial numbers (CFU and PCR) were reduced when M. haemolytica and P. multocida were incubated together on fixed epithelial cells. This inhibition does not appear to result from a soluble factor, as neither conditioned medium nor separation of the two species by a transwell filter membrane reproduced the effect. We infer that when located in close proximity on the epithelial surface, M. haemolytica and P. multocida mutually regulate one another.

Identifying individual animal factors associated with Mycobacterium avium subsp. paratuberculosis (MAP) milk ELISA positivity in dairy cattle in the Midwest region of the United States

BackgroundMycobacterium avium subsp. paratuberculosis (MAP) is a widespread chronic disease of ruminants that causes severe economic losses to the dairy cattle industry worldwide. The objective of this study was to evaluate the association between individual cow MAP-ELISA and relevant milk production predictors in dairy cattle using data routinely collected as part of quality and disease control programs in the Midwest region of the U.S. Milk ELISA results of 45,652 animals from 691 herds from November 2014 to August 2016 were analyzed.ResultsThe association between epidemiological and production factors and ELISA results for MAP in milk was quantified using four individual-level mixed multivariable logistic regression models that accounted for clustering of animals at the farm level. The four fitted models were one global model for all the animals assessed here, irrespective of age, and one for each of the categories of < 4 year-old, 4–8 year-old, and > 8 year-old cattle, respectively.A small proportion (4.9%; n = 2222) of the 45,652 tested samples were MAP-seropositive. Increasing age of the animals and higher somatic cell count (SCC) were both associated with increased odds for MAP positive test result in the model that included all animals, while milk production, milk protein and days in milk were negatively associated with MAP milk ELISA. Somatic cell count was positively associated with an increased risk in the models fitted for < 4 year-old and 4–8 year-old cattle. Variables describing higher milk production, milk protein content and days in milk were associated with significantly lower risk in the models for 4–8 year-old cattle and for all cattle.ConclusionsOur results suggest that testing cows with high SCC (> 26 × 1000/ml), low milk production and within the first 60 days of lactation may maximize the odds of detecting seropositive animals. These results could be useful in helping to design better surveillance strategies based in testing of milk.

Differential proteomic profiling of endometrium and plasma indicate the importance of hydrolysis in bovine endometritis

Endometritis is an important disease of dairy cows that leads to significant economic losses in the dairy cattle industry. To investigate the alteration of proteins associated with endometritis in the dairy cow, the isobaric tags for relative and absolute quantification (iTRAQ) technique was applied to quantitatively identify differentially expressed proteins (DEP) in the endometrium and peripheral plasma of Chinese Holstein cows with endometritis. Compared with the normal (control) group, 159 DEP in the endometrium and 137 DEP in the plasma were identified in cows with endometritis. Gene ontology analysis demonstrated that the predominant endometrial DEP were primarily involved in responses to stimulus and stress processes and mainly played a role in hydrolysis in the extracellular region. The predominant plasma DEP were mainly components of the cytosol and non-membrane-bound organelles, and they were involved in the response to stress and regulation of enzyme activity. Protein-protein interaction of tissue DEP revealed that some core seed proteins, such as RAC2, ITGB2, and CDH1 in the same network as CD14, MMP3, and MMP9, had important functions in the cross-talk of pathways related to extracellular proteolysis. In summary, significant enzymatic hydrolase activity in the extracellular region is proposed as a molecular mechanism by which altered proteins may promote inflammation and hence endometritis.

In this issue – September 2017

In this issue – September 2017

Multiple criteria decision-making process to derive consensus desired genetic gains for a dairy cattle breeding objective for diverse production systems

Dairy cattle industries contribute to food and nutrition security and are a source of income for numerous households in many developing countries. Selective breeding can enhance efficiency in these industries. Developing dairy industries are characterized by diverse production and marketing systems. In this paper, we use weighted goal aggregating procedure to derive consensus trait preferences for different producer categories and processors. We based the study on the dairy industry in Kenya. The analytic hierarchy process was used to derive individual preferences for milk yield (MY), calving interval (CIN), production lifetime (PLT), mature body weight (MBW), and fat yield (FY). Results show that classical classification of production systems into large-scale and smallholder systems does not capture all differences in trait preferences. These differences became apparent when classification was based on productivity at the individual animal level, with high and low intensity producers and processors as the most important groups. High intensity producers had highest preferences for PLT and MY, whereas low intensity producers had highest preference for CIN and PLT; processors preferred MY and FY the most. The highest disagreements between the groups were observed for FY, PLT, and MY. Individual and group preferences were aggregated into consensus preferences using weighted goal programming. Desired gains were obtained as a product of consensus preferences and percentage genetic gains (G%). These were 2.42, 0.22, 2.51, 0.15, and 0.87 for MY, CIN, PLT, MBW, and FY, respectively. Consensus preferences can be used to derive a single compromise breeding objective for situations where the same genetic resources are used in diverse production and marketing circumstances.

Improvements in diagnosis of disease caused by Mycoplasma bovis in cattle

The major disease problems associated with Mycoplasma bovis are contagious mastitis and respiratory disease in cattle. Its importance has increased worldwide due to its increasing resistance to antimicrobial agents and the lack of an effective vaccine. Chronically infected silent carriers introduce infection to naïve herds and M. bovis diseases can cause significant economic losses to the affected herds. Availability of a suitable diagnostic tool for extensive screening will improve the ability to determine the appropriate treatment and the full impact of M. bovis in both beef and dairy cattle industries. The present review focuses on the past and present improvements in the diagnosis of disease caused by M. bovis in cattle.

Dairy cattle industry and genetic improvement programs in Thailand

The objective of the present study was to estimate genetic parameters and evaluate the genetic trends of 100-day milk yield (MY), fat percentage (FP) and protein percentage (PP) in three government dairy cattle farms in Thailand, located in the north and north-east of the country. The data consisted of records from 1745 first-lactation cows that calved between 1986 and 2015, which were the progeny of 287 sires and 1237 dams. Most of the animals were crossbred Holstein-Friesian with native or zebu animals. The total number of animals in the pedigree was 4753. Univariate and bivariate linear mixed models were used to estimate genetic parameters and breeding values by using ASReml-R. The fixed effects in the model were herd, year of calving, season of calving, breed group and the interaction between year and season of calving, and the random effects were animal and residual. All fixed effects had significant effects on the three traits, except breed group. The estimated heritabilities for MY, FP and PP were 0.242 ± 0.061, 0.066 ± 0.048 and 0.329 ± 0.072 respectively. The genetic correlation for MY and FP, MY and PP, and FP and PP were 0.219 ± 0.352, –0.271 ± 0.177 and 0.452 ± 0.255 respectively. The genetic trends based on estimated breeding values over year of birth did not show consistent improvement in all three traits, although there was a slight declining trend in MY in the later years.

Identification of Candida strains with nested PCR in bovinemastitis and determination of antifungal susceptibilities

Mastitis is one of the biggest problems of dairy cattle industries. In recent years, fungal agents have been frequently reported among the causative agents for mastitis. Among the fungal agents, Candida species are the most common. This study's aims were the isolation, identification, and determination of antifungal susceptibility of Candida species causing mycotic mastitis in cattle. A total of 260 mastitic milk samples were collected from different farms. Identification was conducted by rapid diagnostic tests and nested PCR method; 6 different antifungal agents were examined. Candida sp. was detected in 46 (17.7%) of the 260 mastitic milk samples. Based on API 20 C AUX and nested PCR test results, 6 different species of Candida were identified. C. tropicalis was the predominant one (26.1%), followed by C. parasilosis (21.7%), C. kefyr and C. krusei (17.4% each), C. rugosa (13%), and C. glabrata (4.4%). A total of 46 strains were confirmed by PCR. According to antifungal test results, the isolates were found to be susceptible to ketoconazole (78.3%) and resistant to flucytosine (91.3%), amphotericin (82.6%), miconazole and nystatin (73.9%), and fluconazole (69.5%).

Whole-Genome Resequencing of Holstein Bulls for Indel Discovery and Identification of Genes Associated with Milk Composition Traits in Dairy Cattle.

The use of whole-genome resequencing to obtain more information on genetic variation could produce a range of benefits for the dairy cattle industry, especially with regard to increasing milk production and improving milk composition. In this study, we sequenced the genomes of eight Holstein bulls from four half- or full-sib families, with high and low estimated breeding values (EBVs) of milk protein percentage and fat percentage at an average effective depth of 10×, using Illumina sequencing. Over 0.9 million nonredundant short insertions and deletions (indels) [1–49 base pairs (bp)] were obtained. Among them, 3,625 indels that were polymorphic between the high and low groups of bulls were revealed and subjected to further analysis. The vast majority (76.67%) of these indels were novel. Follow-up validation assays confirmed that most (70%) of the randomly selected indels represented true variations. The indels that were polymorphic between the two groups were annotated based on the cattle genome sequence assembly (UMD3.1.69); as a result, nearly 1,137 of them were found to be located within 767 annotated genes, only 5 (0.138%) of which were located in exons. Then, by integrated analysis of the 767 genes with known quantitative trait loci (QTL); significant single-nucleotide polymorphisms (SNPs) previously identified by genome-wide association studies (GWASs) to be associated with bovine milk protein and fat traits; and the well-known pathways involved in protein, fat synthesis, and metabolism, we identified a total of 11 promising candidate genes potentially affecting milk composition traits. These were FCGR2B, CENPE, RETSAT, ACSBG2, NFKB2, TBC1D1, NLK, MAP3K1, SLC30A2, ANGPT1 and UGDH. Our findings provide a basis for further study and reveal key genes for milk composition traits in dairy cattle.

What can Akabane disease teach us about other arboviral diseases.

Viruses of the Simbu serogroup cause lesions to foetuses that are seen at birth and that correlate with the stage of pregnancy at which the dam first contracts the virus. The Simbu serogroup comprises arboviruses known to cause outbreaks of abnormal parturitions in domestic ruminants; these abnormalities include abortion, stillbirth, and congenitally deformed neonates. Simbu serogroup members include: Akabane virus (AKAV), Aino virus, Cache Valley virus, and Schmallenberg virus. Lately, dairy herds calf malformations have been observed in Europe, where there have been reports of clinical manifestations such as diarrhoea, fever, and reduced milk yield in adult lactating cows. The Israeli dairy cattle industry has experienced 2 major episodes of abnormal parturitions that resulted from 2 arboviral Simbu serogroup episodes, which occurred 35 years apart. A wave of apparently newly introduced AKAV was noted from the beginning of January 2012. Investigations carried out throughout the period of late Summer 2011 to early Winter 2012, associated the Israeli AKAV strain with central nervous system manifestations in lactating cows. A lack of clinical/epidemiological 'uniformity' among the AKAV infections was noted during these investigations. Here we describe and discuss the clinical and spatial distribution differences found among the 3 above-mentioned outbreaks. Comparable features in the clinical presentation, spatial distribution, and target‑animal issues relating to Akabane disease are discussed.

Identification of Leukotoxin and other vaccine candidate proteins in a Mannheimia haemolytica commercial antigen.

Bovine Respiratory Disease is the most costly disease that affects beef and dairy cattle industry. Its etiology is multifactorial, arising from predisposing environmental stress conditions as well as the action of several different respiratory pathogens. This situation has hindered the development of effective control strategies. Although different type of vaccines are available, many currently marketed vaccines are based on inactivated cultures of the main viral and bacterial agents involved in this pathology. The molecular composition of commercial veterinary vaccines is a critical issue. The present work aims to define at the proteomic level the most relevant valence of a line of commercial respiratory vaccines widely used in Central and South America. Since Mannheimia haemolytica is responsible for most of the disease associated morbid-mortality, we focused on the main proteins secreted by this pathogen, in particular Leukotoxin A, its main virulence factor. By Western blot analysis and mass spectrometry, Leukotoxin A was identified as a major component of M. haemolytica culture supernatants. We also identified other ten M. haemolytica proteins, including outer membrane proteins, periplasmic transmembrane solute transporters and iron binding proteins, which are relevant to achieve protective immunity against the pathogen. This work allowed a detailed molecular characterization of this vaccine component, providing evidence of its quality and efficacy. Furthermore, our results contributed to the identification of several proteins of interest as subunit vaccine candidates.

Genome-wide association study for longevity with whole-genome sequencing in 3 cattle breeds

Longevity is an important economic trait in dairy production. Improvements in longevity could increase the average number of lactations per cow, thereby affecting the profitability of the dairy cattle industry. Improved longevity for cows reduces the replacement cost of stock and enables animals to achieve the highest production period. Moreover, longevity is an indirect indicator of animal welfare. Using whole-genome sequencing variants in 3 dairy cattle breeds, we carried out an association study and identified 7 genomic regions in Holstein and 5 regions in Red Dairy Cattle that were associated with longevity. Meta-analyses of 3 breeds revealed 2 significant genomic regions, located on chromosomes 6 (META-CHR6–88MB) and 18 (META-CHR18–58MB). META-CHR6–88MB overlaps with 2 known genes: neuropeptide G-protein coupled receptor (NPFFR2; 89,052,210–89,059,348 bp) and vitamin D-binding protein precursor (GC; 88,695,940–88,739,180 bp). The NPFFR2 gene was previously identified as a candidate gene for mastitis resistance. META-CHR18–58MB overlaps with zinc finger protein 717 (ZNF717; 58,130,465–58,141,877 bp) and zinc finger protein 613 (ZNF613; 58,115,782–58,117,110 bp), which have been associated with calving difficulties. Information on longevity-associated genomic regions could be used to find causal genes/variants influencing longevity and exploited to improve the reliability of genomic prediction.

English

A cross-sectional study was conducted in Asella and Bishoftu towns of Oromia Regional State of Ethiopia to determine seropositivity and associated risk factors exposing dairy cattle to brucellosis from December, 2013 to March, 2014. A total of 570 dairy cattle from 35 herds were purposely selected for inclusion in the study based on abortion history. From 35 farms studied, 80, 55.56 and 100% of the farm owners in small, medium and large herd sizes responded as they were aware of brucellosis, respectively. It was also found out that all farm owners of the study area were dependent on culling of the known Brucella infected animals, while most of the farm owners dispose the after birth to open dump in small and medium herd size farms. All sera sample collected were tested and confirmed serologically using the card test (CT), rose Bengal plate test (RBPT), indirect enzyme linked immuno sorbent assay (i-ELISA) and complement fixation test (CFT). Out of 570 samples tested in the present study, an overall sero prevalence was estimated 1.4% (95% CI: 0.241, 3.461) by complement fixation test (CFT). Among the tested samples, 13 (2.28%), 15 (2.63%) and 16 (2.81%) were found positive by the aforementioned tests, respectively. The higher seroprevalence, 3.23% (95% CI: 3.0, 7.4) was observed in Asella compared to Bishoftu (0.52%) town. A Chi-square computed statistical analysis indicated that origin (&chi;2=6.63; P&lt;0.05), breed type (&chi;2= 8.49; P&lt;0.05), abortion history (&chi;2=92.43; P&lt;0.001) and abortion period (&chi;2=192.97; P&lt;0.001) were the major risk factors for Brucella infection in the study areas. Multivariable logistic regression statistical analysis revealed that origin and breed type were significantly associated with Brucella seropositivity (P&lt;0.05). Consequently, origin was statistically identified to be the major risk factor for brucellosis to occur in relation to other factors (OR=7.56). In conclusion, the prevailing Brucella seropositivity in most of the dairy farms of the study areas signifies the economic importance of brucellosis in the dairy cattle industry and the potential public health implication for human population. Therefore, more proactive measures should be taken to protect the cattle populations from Brucella infection to reduce its economic impact to the dairy industry and the risk of zoonotic infection in exposed human population in the study areas. Key words:&nbsp; Asella, Bishoftu, brucellosis, dairy cattle, seropositivity, risk factors.

A space-time analysis of Mycoplasma bovis: bulk tank milk antibody screening results from all Danish dairy herds in 2013-2014.

Background Mycoplasma bovis is an important pathogen causing severe disease outbreaks in cattle farms. Since 2011, there has been an apparent increase in M. bovis outbreaks among Danish dairy cattle herds. The dairy cattle industry performed cross-sectional antibody screening for M. bovis on four occasions, using the indirect BIO K 302 M. bovis enzyme-linked immunosorbent assay (ELISA) (Bio-X, Belgium) in bulk tank milk from all dairy herds between June 2013 and July 2014. The objective of this study was to investigate the evolution of the spatial distribution of M. bovis in the Danish dairy herd population throughout the study period. Repeated bulk tank milk samples were used as a proxy for the herd-level diagnosis. Descriptive and spatial analyses were performed for the four screening rounds. Based on a previous diagnostic test evaluation study, the M. bovis status for each herd was determined as test-positive or test-negative using a cut-off of 50 optical density coefficient %. The spatial global clustering was evaluated through a modified K-function method, and local clusters were identified by scan statistics.ResultsThe results showed that M. bovis test-positive herds had a dynamic pattern in space. The global clustering analysis showed that M. bovis test-positive herds were spatially correlated in rounds one, three and four. These findings were supported to some extent by the local clustering analysis, which found significant high- and low-risk spatial clusters in rounds one and three in the north and south of the mainland.ConclusionThe clusters with a high risk of observing test-positive herds did not remain between sampling rounds, indicating that M. bovis did not tend to persist upon emergence in dairy herds. In contrast, the clusters with a low risk of observing test-positive herds persisted in the same area throughout the study period.

Producer uptake

The Bovine Respiratory Disease Complex Coordinated Agricultural Project (BRD CAP) is a 5-year USDA-funded Coordinated Agricultural Project to develop genetic markers associated with bovine respiratory disease (BRD) to identify cattle that are less susceptible to BRD. Ultimately the aim of this project is to integrate predictive markers for BRD susceptibility into genetic tests and national cattle genetic evaluations. Work is ongoing to identify regions of the genome associated with BRD susceptibility in both dairy and beef cattle. Initial results have identified multiple genomic regions that were significantly associated with BRD susceptibility. Genomic information has typically been integrated into genetic evaluations based on linkage disequilibrium (LD) between single nucleotide polymorphism (SNP) markers and the causative mutations affecting economically relevant traits. This has been successful to develop selection within breeds in the dairy cattle industry, but has been more problematic in the beef cattle industry due to the presence of numerous breeds and the importance of crossbreeding in the commercial cattle population. LD between markers and QTL has not be consistent across breeds, and so markers that were identified in 1 breed were frequently uninformative in other breeds. However, the sequencing of a large number of animals has opened up the possibility of identifying the actual SNP variations that are causing genetic variation and performing sequenced-based genomic selection of cattle. There are several advantages associated with this approach including persistence of the marker affect across generations, and an increased likelihood that causative polymorphisms will be similarly associated with variation across multiple breeds. It is envisioned that by imputing the genotypes of reference animals collected by the BRD CAP up to full sequence and further fine mapping and analyses, that the causative genetic variants associated with BRD susceptibility will be identified, and that inclusion of these markers on genotyping platforms will provide a reliable selection criterion to enable for the selection of both beef and dairy cattle that are less susceptible to BRD.

Causal relationships between milk quality and coagulation properties in Italian Holstein-Friesian dairy cattle.

BackgroundRecently, selection for milk technological traits was initiated in the Italian dairy cattle industry based on direct measures of milk coagulation properties (MCP) such as rennet coagulation time (RCT) and curd firmness 30 min after rennet addition (a30) and on some traditional milk quality traits that are used as predictors, such as somatic cell score (SCS) and casein percentage (CAS). The aim of this study was to shed light on the causal relationships between traditional milk quality traits and MCP. Different structural equation models that included causal effects of SCS and CAS on RCT and a30 and of RCT on a30 were implemented in a Bayesian framework.ResultsOur results indicate a non-zero magnitude of the causal relationships between the traits studied. Causal effects of SCS and CAS on RCT and a30 were observed, which suggests that the relationship between milk coagulation ability and traditional milk quality traits depends more on phenotypic causal pathways than directly on common genetic influence. While RCT does not seem to be largely controlled by SCS and CAS, some of the variation in a30 depends on the phenotypes of these traits. However, a30 depends heavily on coagulation time. Our results also indicate that, when direct effects of SCS, CAS and RCT are considered simultaneously, most of the overall genetic variability of a30 is mediated by other traits.ConclusionsThis study suggests that selection for RCT and a30 should not be performed on correlated traits such as SCS or CAS but on direct measures because the ability of milk to coagulate is improved through the causal effect that the former play on the latter, rather than from a common source of genetic variation. Breaking the causal link (e.g. standardizing SCS or CAS before the milk is processed into cheese) would reduce the impact of the improvement due to selective breeding. Since a30 depends heavily on RCT, the relative emphasis that is put on this trait should be reconsidered and weighted for the fact that the pure measure of a30 almost double-counts RCT.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-015-0123-7) contains supplementary material, which is available to authorized users.

Antimicrobial resistance and virulence-related genes of Streptococcus obtained from dairy cows with mastitis in Inner Mongolia, China

Context: Mastitis is the most expensive disease in the dairy cattle industry and results in decreased reproductive performance. Streptococcus, especially Streptococcus agalactiae, possesses a variety of virulence factors that contribute to pathogenicity.Objective: Streptococcus isolated from mastitis was tested to assess the prevalence of antimicrobial resistance and distribution of antibiotic resistance- and virulence-related genes.Materials and methods: Eighty-one Streptococcus isolates were phenotypically characterized for antimicrobial resistance against 15 antibiotics by determining minimum inhibitory concentrations (MIC) using a micro-dilution method. Resistance- and virulence-related genes were detected by PCR.Results: High percentage of resistance to β-lactams, along with tetracycline and erythromycin, was found. Resistance to three or more of seven antimicrobial agents was observed at 88.9%, with penicillin–tetracycline–erythromycin–clindamycin as the major profile in Streptococcus isolates. Resistant genes were detected by PCR, the result showed that 86.4, 86.4, 81.5, and 38.3% of isolates were mainly carrying the pbp2b, tetL, tetM, and ermB genes, respectively. Nine virulence genes were investigated. Genes cyl, glnA, cfb, hylB, and scaA were found to be in 50% of isolates, while 3.7, 21, and 4.9% of isolates were positive for bca, lmb, and scpB, genes, respectively. None of the isolates carried the bac gene.Discussion and conclusion: This study suggests the need for prudent use of antimicrobial agents in veterinary clinical medicine to avoid the increase and dissemination of antimicrobial resistance arising from the use of antimicrobial drugs in animals.

English

Mastitis causes inflammation of the mammary gland and physical, chemical and bacteriological alterations in milk. The control of this disease deserves special attention within health programs of the dairy cattle industry. The aim of the present study was to assess the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of a commercial product (gentamicin + amoxicillin) indicated for the treatment of mastitis, propolis,and their association against Staphylococcus spp. In total, 70 samples of Staphylococcus spp. isolated from cases of subclinical mastitis, were used in the present study. The bacterial isolates were tested against the commercially available association of gentamicin and amoxicillin, as well as commercially available propolis. Muller Hinton (MH) micro-broth dilution was used in the present study. The presence of phenolic compounds and flavonoids was confirmed in the propolis used. The MIC values ​​found for gentamicin and amoxicillin were 0.2258 g/ml and 0.8469 mg/ml, respectively. The MBC values found for gentamicin and amoxicillin were 1.7793 and 6.6722 mg/ml, respectively. The mean MBC values of amoxicillin and gentamicin in synergism with propolis were 0.1384 g/ml and 0.5235 mg/ml, respectively. Analysis of propolis showed the presence of derivatives of the following acids: caffeic; cinnamic; p-coumaric; ferulic and 3,4-dihydroxybenzoic. The results of the present study showed that gentamicin and amoxicillin, associated with propolis, exhibit synergistic activity that could reduce the selection of resistant microorganisms. The synergistic effect of propolis is probably due to the presence of cinnamic acid derivatives. Key words: Antimicrobial, bovine mastitis, propolis, Staphylococcus spp.

A cross sectional study on reproductive health disorders in dairy cattle in Sudan

A cross sectional survey was carried out in dairy farms in four States of Sudan to determine prevalence of reproductive health disorders that affect dairy cattle industries in the country. A total of 575 adult female cows in dairy farms located in Khartoum, Gezira, Sennar, and White Nile States were investigated using questionnaire survey and face-to-face interviews with the owners. The results indicated that 24.4% of the animals were affected with one or more reproductive health disorders. Abortion (57.1%) represented the major health problem affecting calf yield, followed by infertility (34.3%) and neonatal death (8.6%). Other health problems included stillbirth, vaginitis and retained placenta, anomalies, metritis and repeat breeder. Most of the abortion cases were detected during third trimester (76.25%) followed by first (12.5%) and second (11.25%) trimesters. Finally, countrywide investigations of reproductive disorders and increasing awareness to the owners are recommended for designing successful control strategies of reproductive disorders in Sudan. http://dx.doi.org/10.5455/javar.2015.b57