Wagdy ElAshmawy

Antimicrobial drug (AMD) use for bovine respiratory disease (BRD) continues to be concerning for development of antimicrobial resistance (AMR) in respiratory and enteric bacteria of cattle. This study aimed to provide data regarding AMR in respiratory isolates, and identify relationships between respiratory and enteric AMD susceptibility, in weaned dairy heifers. A cross-sectional study was performed between June of 2019 and February 2020, on 6 calf rearing facilities in California. Deep nasopharyngeal and rectal swabs were collected from 341 weaned heifers and submitted for selective bacterial culture and AMR testing. Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni were selectively isolated from respiratory samples; Escherichia coli and Enterococcus spp. were selectively isolated from rectal swabs. Minimum inhibitory concentrations (MIC) were determined for selected isolates against 19 AMD. The proportion of resistant isolates was calculated using Clinical Laboratory Standards Institute (respiratory) or USDA NARMS (enteric) breakpoints; when no applicable breakpoint was available, the distribution of MIC was described and compared. Association between AMR in a calf's respiratory isolate and a higher or lower MIC of the matched enteric isolates was determined. More than 50% of P. multocida isolates were resistant to each of 7 AMD commonly used to treat BRD (florfenicol, gamithromycin, tildipirosin, tilmicosin, danofloxacin, enrofloxacin and tetracycline). Resistance in respiratory isolates was only associated with higher matched enteric MIC for gamithromycin and tulathromycin. Multidrug resistance was reported in >70% of P. multocida and M. haemolytica isolates. Antimicrobial resistance, including multidrug resistance, in respiratory isolates appears to be widespread in weaned dairy heifers; this finding has not previously been reported and raises concern for the future efficacy of AMD used to treat respiratory diseases in weaned dairy heifers. Enteric bacterial MIC appear to have limited direct association with respiratory isolate AMR classification.

Stable flies (Stomoxys calcitrans) are blood-sucking insects commonly associated with cattle production systems worldwide and are known to cause severe irritation to cattle due to painful bites. Cattle react to biting stable flies with an aggregating behavior known as bunching. Bunching behavior reduces grazing or feed consumption and thus reduces cattle productivity and welfare. Cattle's fly-repelling behaviors include foot stomping, head tossing, tail switching and skin twitching. A longitudinal study was conducted in 2017 on 20 California dairies (average lactating herd size = 2,466 (SE±28.392)) during the stable fly season from April to July. The study objectives were to estimate the association between environmental factors and dairy characteristics including facility design, feed and manure management, total mixed ration (TMR) components fed to cattle, and operational pest management procedures and the outcome stable fly activity on California dairies. Stable fly activity was measured by counting stable flies on cow forelimbs (leg count) and on Alsynite traps (trap count) over the 13-week study period. Weekly leg counts were performed for cattle in lactating cow pens (31 pens from 10 study dairies) with counts made during the morning (AM) and again during the afternoon (PM). Trap counts were performed on all 20 study dairies. Data were analyzed using linear mixed models which revealed temporal variation in the average leg and trap counts with stable fly activity increasing from May to June and then decreasing to the lowest activity in July. Leg counts were higher during the afternoon compared to morning. Ambient temperatures ≤30⁰C and relative humidity (RH) measurements <50% were associated with higher leg and trap counts. Traps located at the periphery of study dairies had higher stable fly counts compared to traps located in the interior of the dairy. Cow pens with trees on the periphery had higher leg counts in comparison to pens away from trees. Specific TMR components were associated with both leg and trap counts. Dairies feeding by-products including almond hulls, wet distillers' grain, fruits, and vegetables had higher trap counts compared to dairies that did not feed these ingredients. At the pen level, pens with rations that contained straw had lower average leg counts compared to pens fed with rations that did not contain straw. A similar association was observed for pens with rations that contained wheat silage when ambient temperatures were ≤30⁰C. In contrast, pens with water added to the TMR while the RH was ≥50% had higher average leg counts compared to pens without water added to the TMR. Dairies that applied insecticides for fly control to their entire facility had lower trap counts compared to dairies that did not apply insecticides. Stable fly activity measured on California dairies using leg and trap counts varied according to the month, environmental factors, pen surroundings, trap location, TMR components, and insecticide use.

The California (CA) dairy industry was surveyed in July 2017 to evaluate producers' knowledge and perceptions and antimicrobial drug (AMD) use in preweaned dairy calves following the implementation of the nationwide veterinary feed directive final rule (VFD) in January 2017 and prior to statewide implementation of CA Senate Bill (SB) 27 in January 2018. Together, these regulations require veterinary oversight for all uses of medically important antimicrobial drugs (MIADs) administered to livestock in CA. Survey questionnaire was mailed to 1,361 CA Grade A milk producing dairies and calf ranches across CA resulting in a 12% (169) response. Most respondents (83%) were aware of the VFD and SB 27 changes. Use of antibiotics was perceived as important (77%) in raising preweaned dairy calves and judicious use of antibiotics was ranked as the most important antimicrobial stewardship practice, amongst record keeping, observing withdrawal periods, having a valid Veterinarian-Client-Patient-Relationship (VCPR), and use of alternatives to antibiotics. Treating sick calves was the major indication for AMD use (90.5%); however, few producers reported use of antibiotics to control (12.7%) or prevent disease (11%). Neomycin sulfate, chlortetracycline, oxytetracycline and sulfamethazine were the most used AMD. The respondents reported a decreased use of AMD in milk (10%) and in solid feed (5%), and discontinuation of one or more AMDs used in milk (18.6%) or in solid feed (5%) post-VFD rule implementation in 2017. Most respondents reported keeping treatment records and the information recorded included date (82%), dose (44%) and route (15%) of AMD used. A few respondents reported they had initiated use of alternatives to AMDs, such as vitamins (32.6%), minerals (25.6%), herbal remedies (11.6%) and pathogen specific antibodies (7%), post-VFD. The limited changes noted in AMD use could be attributed to the short period between the implementation of the VFD and the time of the survey. Our study outcomes identified opportunities to improve AMD use practices, including record keeping and use of AMD alternatives, and provides a baseline for future evaluation of the impact of these regulatory changes, as well as guidance for the future recommendations on best practices to promote judicious AMD use.

Ringworm is a fungal and zoonotic infectious disease, caused by different species of der - matophytes. In this study, skin scrapings and hair samples were collected from beef calves recently introduced into a beef farm they have clinical signs of dermatophytosis. The collected samples were directly examined for fungal elements by direct microscopy and fungal culture. Fungal culture re- vealed Trichophyton verrucosum. The antifungal activity of Bergamot oil (Citrus Bergamia) alone or in combination with salicylic acid using different concentrations was evaluated in vitro and revealed that Bergamot oil with different dilutions (1.25%, 2.5% and 5%) has a very effective antifungal effect against Trichophyton verrucosum

Foot and mouth disease is one of the economically important viral diseases of cattle resulting in high mortalities in young calves and reduction of production in adult animals. Egypt was endemic with serotypes O and A till march 2012 outbreak where serotype SAT2/2012 was isolated and resulted in high mortalities in young calves and adult cattle. Our study was carried out during 2012 FMD outbreak on 22 adult cattle with clinical picture suggesting FMD infection. Saliva, tongue epithelium and vesicular fluids were collected from clinically affected animals and FMD serotype SAT2/2012 was isolated from all animals. Hematological and biochemical examination was carried out on affected animals and revealed that, there's significant reduction in total protein, albumin, globulin, cholesterol and calcium. CPK level was increased in 3 samples out of 22 samples which is an indication of the degenerative effect of SAT2/2012 on the myocardium. Postmortem and histopathological examinations were carried out on the heart of dead adult animals and compared with the heart of young calves died from FMD during 2012 outbreak. There's grayish white small foci of necrosis present mainly at heart base, these areas were friable and appeared as cooked and pale. There's hyaline degeneration and zenker's necrosis of some myocytes. There were myolysis and complete disappearance of some myocytes with presence of large numbers of mononuclear cells infiltration.

In this study serum samples were collected from 4 different groups of cattle, Group I (non-vaccinated Brucella infected group), Group II (Vaccinated Brucella infected group), Group III (Non-vaccinated Brucella free group) and Group IV (vaccinated Brucella free group). These samples were subjected to the different serological tests including Rose Bengal plate antigen test, Tube Agglutination test, Rivanol test, Indirect Enzyme Linked Immunosorbent Assay and Competitive Enzyme Linked Immunosorbent Assay. Statistical analysis of the obtained results in different cattle groups was carried out using Latent Class Analysis (Lem model). The prevalence of brucellosis was 6.4%, the sensitivity of RBPT was 96.1% while its specificity was 99.3%, the sensitivity of Rivanol test was 85% while its specificity was 100%, the sensitivity of Indirect Enzyme Linked Immunosorbent assay was 100% while its specificity was 98.3 % and the sensitivity of Competitive Enzyme Linked Immunosorbent assay was 97.1% while its specificity was 100%. The results proved that, the most sensitive test was Indirect Enzyme Linked Immunosorbent assay while the most specific test was Competitive Enzyme Linked Immunosorbent assay. This study therefore, recommends the use of Indirect Enzyme Linked Immunosorbent assay as a screening test and Competitive Enzyme Linked Immunosorbent assay as a confirmatory test. Bacteriological examination was carried out on supramammary lymph nodes and spleen of some slaughtered seropositive cattle, the rate of isolation was 25% from non-vaccinated infected group and 10% from vaccinated infected group. Brucella melitensis biovar3 was recovered only from supramammary lymph nodes.

Aim: Due to inadequate data on the dynamics of foot and mouth disease (FMD) infection in buffalo, the present work was
aimed at investigating some virological and immunological aspects of FMD virus (FMDV) SAT2 infection in naturally
exposed and vaccinated buffalo cows and their calves.
Materials and Methods: The study employed clinical observation and examination, virus isolation in mice and cell culture,
in addition to virus detection using complement fixation test; indirect sandwitch enzyme-linked immunosorbent assay and
demonstration of RNA by reverse transcription polymerase chain reaction for confirmation the results.
Results: FMD type SAT2 antibodies was detected in a protective level by the 1st week post infection and 3rd week post
vaccination and peak titers were recorded by the 3rd week, 12th week in infected and vaccinated buffaloes, respectively.
These titers began to decline to reach their lowest protective levels by the 36th week, 12nd week in infected and vaccinated
buffaloes respectively. The SAT2 antibodies in calves born to vaccinated and infected buffalo cows were detected on
the 1st day post parturation through the suckling of their Dam’s colostrums. The highest maternal antibody titers were
recorded in sera by the 2nd day post parturation. These antibodies declined gradually to reach their lowest protective levels
on 14th week, 16th week post parturition in calves from vaccinated and infected buffaloes, respectively. High antibody titers
in the colostrums and milk of vaccinated and naturally infected buffalo cows were recorded at parturition, and they began to
decrease gradually recording their lowest protective titers by 10th and 12nd week post parturition respectively.
Conclusion: FMDV serotype SAT2 was confirmed as a causative agent of the suspected FMD signs in pregnant buffalo
at El-Fayoum Governorate, Egypt, during 2012. Vaccinated and naturally infected buffalo cows were able to provide their
calves with high levels of maternal derived antibodies through their colostrums, which could protect new born calves for
not less than 14 week post parturation.