Marcos Veiga dos Santos

Marcos Veiga dos Santos
University of São Paulo | USP · Departamento de Nutrição e Produção Animal (VNP) (Sao Paulo)

Ph.D.

About

169
Publications
48,156
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2,726
Citations
Citations since 2016
62 Research Items
1883 Citations
20162017201820192020202120220100200300
20162017201820192020202120220100200300
20162017201820192020202120220100200300
20162017201820192020202120220100200300
Introduction
Skills and Expertise

Publications

Publications (169)
Article
Most new pathogens of humans and animals arise via switching events from distinct host species. However, our understanding of the evolutionary and ecological drivers of successful host adaptation, expansion, and dissemination are limited. Staphylococcus aureus is a major bacterial pathogen of humans and a leading cause of mastitis in dairy cows wor...
Article
Full-text available
The objective of this study was to evaluate the efficacy of the antibiotic therapy associated with vaccination on the microbiological cure rate of subclinical mastitis caused by Staphylococcus aureus in lactating dairy cows. A total of five herds, from which 72 cows (120 mammary quarters - MQ) were diagnosed with S. aureus subclinical mastitis, wer...
Article
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We aimed to evaluate the impact of selective dry cow therapy (SDCT) (protocol 1: antimicrobial combined with internal teat sealant (ITS); vs. protocol 2: ITS alone) on bacterial diversity and the abundance of quarter milk. Eighty high production cows (parity ≤ 3 and an average milk yield of 36.5 kg/cow/day) from the largest Brazilian dairy herd ava...
Article
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This study evaluated (a) the efficacy of an association between injectable antibiotic therapy and sealant (ATBS) on milk yield (MY), somatic cell count (SCC), and prevalence of intramammary infections (IMI); and (b) the efficacy of gonadotropin-releasing hormone (GnRH) on follicular cyst (FCs) resolution (cyclicity at the 45th day in milk; DIM) and...
Article
Staphylococcus aureus is a contagious pathogen frequently associated with bovine mastitis in Brazil. Molecular characterization of Staph. aureus isolated from affected mammary quarters of cows with clinical mastitis (CM) can provide data on epidemiological behavior of this pathogen and antimicrobial susceptibility (AMS) assessment at the genotypic...
Article
Full-text available
It is unknown whether overuse of antimicrobials against clinical mastitis (CM) from Streptococcus uberis is associated with increased antimicrobial resistance (AMR). Therefore, the aim of this study was to evaluate the association between antimicrobial use (AMU) and AMR in relation to the Strep. uberis causing CM in dairy herds. A total of 83 Strep...
Article
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We evaluated the use of MALDI-TOF MS for the identification of 3 major, dairy-associated Prototheca species, namely, Prototheca bovis (formerly P. zopfii genotype 2), P. blaschkeae, and P. ciferrii (formerly P. zopfii genotype 1). The MALDI-TOF MS spectra established for those species were introduced into the reference spectra library of the Bruker...
Article
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Bovine mastitis is an inflammation of the mammary gland in dairy cattle usually caused by bacterial agents and cefquinome is a fourth-generation cephalosporin commonly used in treatment of this disease caused by Staphylococcus spp. in lactating cows due to a broad spectrum. On the other hand, biofilm formation provides protection for bacteria incre...
Article
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Postmilking teat disinfection is one of the main measures used to prevent mastitis caused by contagious pathogens, such as Staphylococcus aureus. The present study evaluated the antimicrobial activity of polyhexamethylene biguanide (PHMB) and PHMB nanoparticles (NP) against mastitis-causing Staph. aureus using a microdilution assay methodology. A t...
Article
The present study hypothesized that partial replacement of ground corn (GC) by pelleted citrus pulp (PCP) and buffering (BF) inclusion in diets of lactating cows does not change lactation performance, but does reduce milk concentration of ionic calcium (iCa), increasing its stability at ethanol test and heating at 140 °C (heat coagulation time – HC...
Article
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In this research communication we address the hypothesis that a single intramammary infusion of casein hydrolyzate (CH) would have a similar effect to three intramammary infusions of CH for drying-off quarters with chronic mastitis (CM) during lactation. Sixty cows with CM were selected and randomly distributed into two treatment groups: (a) three...
Article
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The present study aimed to evaluate the diagnostic performance specificity (Sp), sensitivity (Se), positive predictive value (PPV), negative predictive value (NPV), and accuracy (Acc) of two chromogenic culture media for rapid identification of Gram-positive bacteria causing subclinical mastitis (SCM) in dairy cows. For this, the performance of chr...
Article
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This study aimed to evaluate the diagnostic performance (specificity, Sp; sensitivity, Se; accuracy; positive predictive value; negative predictive value; and Cohen's kappa coefficient, κ, of agreement) of chromogenic culture media for rapid identification of microorganisms isolated from cows with clinical (CM) and subclinical mastitis (SCM). For t...
Article
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The aims of the present study were to provide a portrait of the techno-economic status of dairy herds in Minas Gerais, Brazil, particularly with respect to bulk-tank somatic cell count (BTSCC) data, and to examine the herd-level associations of BTSCC with various economic performance indicators (EPI). Data from 543 herds, 1,052 herd-year records in...
Article
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Staphylococcus aureus can elicit mild to more severe degrees of mastitis in cattle, depending on the response of the host's immune system and the virulence factors of the specific isolate. Several virulence factors are controlled by a global regulatory system, designated accessory gene regulator (agr). Thus, the objective was to examine association...
Article
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Streptococcus uberis is a major cause of environmental mastitis in many regions, and it is associated with clinical and subclinical infections. Although the main source of infection is the environment, reports of strains with a contagious profile have been described. Dot blot hybridization analysis allows the rapid identification of S. uberis popul...
Article
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Internal teat sealant (ITS) at drying off is a strategy used for the prevention of intramammary infections (IMI) during the dry period (DP), as it simulates the keratin plug’s purpose, which is to prevent the access of pathogens into the mammary gland. The results from randomized clinical trials provide valuable information about the efficacy of co...
Article
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Two experiments were conducted to evaluate the effect of the level and degradability of crude protein (CP) on the digestive metabolism and productive performance of dairy cows. In both experiments, 15 Holstein cows with 585 ± 40 kg of body weight were distributed in a Latin square design with five contemporary squares, three periods of 21 days and...
Article
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Background: Staphylococcus argenteus is a new specie positive coagulase staphylococci. We investigate the presence of S. argenteus in isolates previously classified as S. aureus, obtained from the milk of cows with mastitis in Brazil. Results: Among 856 S. aureus tested in chocolate agar, tryptone soya agar and salt egg yolk agar, white or color...
Article
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We evaluated the effects of chronic subclinical mastitis (CSM) caused by different types of pathogens on milk yield and milk components at the cow level. A total of 388 Holstein cows had milk yield measured and were milk sampled three times at intervals of two weeks for determination of SCC and milk composition, and microbiological culture was perf...
Article
This study aimed to evaluate the effects of chronic subclinical mastitis (CSM) on milk production and component yields in dairy cows. A total of six herds located in the Midwest area of São Paulo State, Brazil were selected. Herds were visited once every 2 weeks to measure milk yield and to collect milk samples from lactating Holstein cows. Milk sa...
Article
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Staphylococcus aureus is recognized worldwide as one of the main contagious mastitis agents in cattle and can express a set of antimicrobial resistance genes and virulence-associated genes that explain the wide range of outcomes of intramammary infections. Staphylococcus aureus strains are heterogeneous: their different resistance and virulence pat...
Article
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The aim of this study was to compare the efficacy of two dry-off protocols: (a) dry cow therapy using ciprofloxacin hydrochloride 400 mg followed by the administration of an internal teat sealant composed of 4 g of bismuth subnitrate, and (b) a positive control using dry cow therapy with 250 mg cephalonium followed by the administration of 2.6 g bi...
Article
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A genotypic characterization of Streptococcus uberis isolated from clinical mastitis (CM) in dairy cows, and the association of Strep. uberis genotypes and antimicrobial susceptibility (AMS) was performed. A total of 89 isolates identified as Strep. uberis from 86 dairy cows with CM in 17 dairy herds of Southeastern Brazil were genotyped using rand...
Conference Paper
Full-text available
Milk quality is an important aspect of dairy production that affects milk processing, its technological properties, and consequently the economic efficiency of dairy herds (GONÇALVES, 2017). Therefore, economic losses caused by bovine mastitis are recognized worldwide as a major factor affecting profitability of dairy farms (HOGEVEEN et al., 2011)....
Article
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The objective was to compare standard versus on-plate sample preparation protocols for identification of mastitis bacteria by MALDI-TOF MS. A total of 186 bacterial isolates from cows with subclinical mastitis were identified by MALDI-TOF MS after preparation using two extraction protocols. On-plate protocol was performed by applying the bacterial...
Conference Paper
Full-text available
This study showed the importance of maintaining good teat end health to reduce the possibility of new intramammary infections, and confirmed results of studies conducted previously by other researchers. Quarters with high teat end roughness scores have a significantly higher probability of being infected by mastitis-causing microorganisms. Monitori...
Article
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Objetivou-se avaliar a qualidade do leite cru goiano nos períodos chuvoso e seco dos anos de 2012 a 2014, no estado de Goiás, Brasil, por meio de indicadores higiênicos-sanitário, CBT e CCS, e do contraste com os limites legais. Foram avaliados 1.600 rebanhos leiteiros do estado de Goiás que compuseram o banco de dados do Laboratório de Qualidade d...
Article
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The present study aimed to evaluate the effect of crude protein degradability and corn processing on lactation performance, milk protein composition, milk ethanol stability (MES), heat coagulation time (HCT) at 140°C, and the efficiency of N utilization for dairy cows. Twenty Holstein cows with an average of 162 ± 70 d in milk, 666 ± 7 kg of body w...
Conference Paper
Full-text available
Milk quality is an important aspect of dairy production that affects milk processing, its technological properties, and consequently the economic efficiency of dairy herds (Gonçalves, 2017). Therefore, economic losses caused by bovine mastitis are recognized worldwide as a major factor affecting profitability of dairy farms (Hogeveen et al., 2011)....
Article
The current study was carried out to evaluate the quality of raw milk, in rainy and dry seasons in 2012, 2013 and 2014, in Goiás State, Brazil, by means of the hygienic-sanitary indicators TBC and SCC, comparing with the legal limits of the Normative. A total of 1,600 dairy herds of Goias State, that constitute the database of the Milk Quality Labo...
Article
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We evaluated the inclusion of two crude extracts produced by Streptomyces genus on in vitro dry matter and organic matter digestibility (IVDMD; IVOMD), cumulative gas production, volatile fatty acids (VFA), and methane (CH4) and ammoniacal nitrogen (NH3-N) concentration. The experimental design was randomized blocks with three blocks and four treat...
Article
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Actinobacteria have been researched as a source that produces crude extracts, which contain bioactive compounds able to act as antimicrobial agents. The present investigation evaluated the dose-response effect of two crude extracts, obtained at Caatinga rhizosphere (Caat) and Rhizophora mangle (AMC), on in vitro ruminal fermentation by: cumulative...
Article
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This study identified the association of management practices and herd characteristics with milk quality of bulk tanks in southeastern, Brazil. Milk samples were collected weekly during 8 weeks from 63 dairy herds. Bulk tanks were evaluated for total bacteria (TBC), preliminary incubation (PIC), pasteurization (PC), coliform (CC), and somatic cell...
Article
The objectives of this study were to characterize the pathogen frequency and severity of clinical mastitis (CM) in 20 dairy herds of southeastern Brazil; and to determine the incidence rate of clinical mastitis (IRCM; overall and based on specific-pathogen groups) based on quarter time at risk and its association with risk factors at the herd-level...
Article
Full-text available
The present study aimed to compare two MALDI-TOF identification methods [(a) direct sample identification after pre-incubation; or (b) use of bacteria isolated on pre-culture)] to standard, traditional bench microbiology. A total of 120 quarter milk samples from 40 Holstein lactating cows were screened based on culture-positive results obtained by...
Article
The emergence of antimicrobial resistance to commonly used antibiotics has necessitated the development of new antimicrobial products. Crude extracts produced by actinomycetes contain antimicrobial metabolites that can inhibit bacterial growth. The objective of our study was to evaluate the antimicrobial activity of crude extracts (Caat1-54 and Caa...
Article
Full-text available
The present study hypothesized that intramammary infection (IMI) might reduce milk ethanol stability (MES), mainly when IMI is caused by major pathogens. Thus, this study evaluated the effect of IMI on bovine MES using a natural exposure experimental design. Ninety-four lactating cows from five dairy herds were selected once they were determined to...
Article
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Determination of antimicrobial susceptibility (AMS) of Escherichia coli causing clinical mastitis (CM) according to the phylogenetic groups and its association with descriptors at the cow and herd level may help improve specific strategies for treatment and control of this pathogen in dairy herds. The aims of the present study were to (a) determine...
Article
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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been shown to be an alternative method for identification of bacteria via their protein profile spectra, being able to identify bacteria at the genus, species and even at subspecies level. With the aim of large-scale identification of pathogens causing m...
Article
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The objectives of this study were to: (a) genotypically characterize Streptococcus agalactiae isolates recovered from clinical mastitis (CM) cases in dairy cows and, (b) determine the association of antimicrobial susceptibility (AMS) and genotypes of Strep. agalactiae clustered according to the genetic similarity. A total of 89 Strep. agalactiae is...
Article
Full-text available
Staphylococcus aureus is recognized worldwide as one of the major agents of dairy cow intra-mammary infections. This microorganism can express a wide spectrum of pathogenic factors used to attach, colonize, invade and infect the host. The present study evaluated 120 isolates from eight different countries that were genotyped by RS-PCR and investiga...
Article
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The general objective of this study was to evaluate whether cephapirin sodium is noninferior compared with a positive control broad-spectrum product formulated with a combination of antimicrobials for intramammary treatment of nonsevere clinical mastitis. In addition, we compared the efficacy of treatments on the cure risks of pathogen groups (gram...
Preprint
Full-text available
Staphylococcus aureus (S. aureus) is recognized worldwide as one of the major agents of dairy cow intra-mammary infections. This microorganism can express a wide spectrum of pathogenic factors used to attach, colonize, invade and infect the host. The present study evaluated 120 isolates from eight different countries that were genotyped by RS-PCR a...
Article
Full-text available
This study evaluated the effect of somatic cell count (SCC) on composition and hygienic quality of dairy herd bulk tank milk – specifically, the effect of SCC of bulk tank of dairy herds on composition (fat, protein, total solids, nonfat dry solids) and on total bacterial count (TBC), psychrotrophic count (PC) and coliform count (CC) were evaluated...
Article
Full-text available
The effect of different pathogens was studied by evaluating the contralateral (healthy and infected) mammary quarters of 146 lactating cows. The impact of SM on economic return (quarter milk yield × milk price) was determined by applying milk payment estimates on milk collected from healthy vs. infected glands. Cows were considered infected when th...
Article
Full-text available
The reduction of milk production caused by subclinical mastitis in dairy cows was evaluated through the regression of test-day milk yield on log-transformed somatic cell counts (LnSCC). Official test-day records (n = 1,688,054) of Holstein cows (n = 87,695) were obtained from 719 herds from January 2010 to December 2015. Editing was performed to en...
Article
Full-text available
Using milk leukocyte differentials for diagnosis of subclinical bovine mastitis – CORRIGENDUM - Volume 84 Issue 4 - Juliano Leonel Gonçalves, Roberta L. Lyman, Mitchell Hockett, Rudy Rodriguez, Marcos Veiga dos Santos, Kevin L. Anderson
Article
Full-text available
A ordenha das vacas é uma das atividades mais importantes de uma propriedade leiteira, devido a três aspectos principais: é nessa hora que o produtor coleta o leite, produto resultante de todos os demais esforços realizados na propriedade; é no momento da ordenha que existe alto risco de as vacas contraírem a mastite; é o momento de alto risco de c...
Conference Paper
Electrical bioimpedance spectroscopy (EBS) is a fast, easy and low-cost methodology used for measurement the electrical properties of biological materials. Thus, the present study aimed to evaluate an automatic equipment based on EBS (MilkSpec) for identification of milk adulterations. Bulk milk samples from 2 dairy farms were collected and stored...
Article
Full-text available
This research study aimed to evaluate the use of the milk leukocyte differential (MLD) to: (a) identify quarter milks that are culture-positive; and (b) characterize the milk leukocyte responses to specific groups of pathogens causing subclinical mastitis. The MLD measures the absolute number and relative percentage of inflammatory cells in milk sa...
Article
The purpose of this study was to evaluate the detection limit of matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDITOF MS) for direct identification, without previous microbiological culture, of bovine mastitis-causing bacteria from milk samples. Milk samples (n = 15) were experimentally contaminated with Staphyloc...
Article
Full-text available
Using a natural exposure trial design, the goal of our study was to evaluate the clinical efficacy of an iodine teat disinfectant with barrier properties and a high level of free iodine relative to a conventional iodine teat disinfectant with no barrier properties and low levels of free iodine. During the 18 wk of the trial, quarter milk samples we...
Article
Full-text available
The purpose of the present study was to evaluate the effect of substituting dry corn with rehydrated ensiled (90 days) corn (REC) in dairy cow diets on the nutrient intake, total tract apparent digestibility, and milk yield and composition. Twelve Holstein cows, with an average of 550 (±30 SD) kg of body weight and 220 (±40 SD) days in milk (DIM),...
Article
Full-text available
The objective of this study was to compare ceftiofur hydrochloride with a positive control protocol for intramammary treatment of nonsevere clinical mastitis in dairy cows. A total of 264 clinical mastitis cases on 11 commercial dairy farms were treated with intramammary infusions, once a day for 4 d using 1 of 2 treatments: (1) ceftiofur hydrochlo...
Article
Full-text available
O objetivo do presente estudo foi avaliar o efeito de dois teores proteicos (PB) e duas fontes nitrogenadas na dieta de vacas leiteiras, utilizando cana-de-açúcar como forragem, sobre o consumo, digestibilidade aparente total, produção e composição do leite, e o balanço de nitrogênio. Doze vacas leiteiras Holandesas em estágio intermediário de lact...
Article
Full-text available
O objetivo deste estudo foi avaliar o efeito do tempo de ensilagem sobre a composição química e a degradabilidade in situ do amido do milho moído hidratado (MMH) em grãos de média vitreosidade. Os grãos de milho foram colhidos com 83% de matéria seca (MS) e vitreosidade de 67% ± 3, e foram secos até atingirem 87% de MS. Os grãos foram moídos a dois...
Article
Full-text available
The current pricing process of raw milk in Brazil discourages producers from improving milk composition, which affects both yield and quality of dairy products. Furthermore, small and medium-sized dairies face great difficulties when it comes to planning production. Thus, a linear programming model was developed to price the raw milk and determine...
Article
Full-text available
The present study aimed to evaluate the effect of dietary cation–anion difference (DCAD) on ruminal fermentation, total apparent digestibility, blood and renal metabolism of lactating dairy cows. Sixteen Holstein cows were distributed in four contemporary 4×4 Latin Square designs, which consisted of four periods of 21 days and four treatments accor...
Article
Full-text available
The aim of this study was to evaluate four main sources of dietary nitrogen on the efficiency of nitrogen utilization and digestive metabolism of dairy cows fed diets with sugarcane as forage. Twelve multiparous Holstein cows, averaging 150 days in milk and 16.9 kg of milk/day, were distributed into three balanced and contemporary 4 × 4 Latin squar...
Article
Subclinical mastitis caused by Corynebacterium spp. (as a group and at the species level) was investigated by evaluating contralateral (healthy and infected) mammary quarters for somatic cell count (SCC), milk yield and composition. Selection of cows with subclinical mastitis caused by Corynebacterium spp. was performed by microbiological culture o...
Article
Full-text available
We very much appreciate the interest in our recent publication “Bovine subclinical intramammary infection caused by coagulase-negative staphylococci increases somatic cell count but has no effect on milk yield and composition” (Tomazi et al., 2015).
Conference Paper
The aim was to evaluate the effect of dietary crude protein (CP) content on milk yield and composition for dairy cows fed with rehydrated corn silage (RCS) and sugar cane silage (SS). Fifteen Holstein cows were distributed in 3 contemporary 3 × 3 Latin square design and diets consisted of 600g / kg dry matter (DM) of SS, 400g / kg DM of RCS and CP...