The Economic Evaluation of Mastitis Control Strategies in Holstein-Friesian Dairy Herds.

The economic evaluation of mastitis control is challenging. The objective of this study was to perform the economic evaluation of mastitis control, under different intervention scenarios, quantifying the total cost of mastitis caused by S. aureus in Holstein cows in Argentina. A model was set for a dairy herd of Holstein cows endemically infected with S. aureus. A basic mastitis control plan including proper milking procedures, milking machine test, dry cow therapy, and treatment for clinical mastitis, was compared against other more complex and costly interventions, such as segregation and culling of chronically infected cows. Sensitivity analysis was performed by modifying the intramammary infection transition probabilities, economic parameters, and efficacy of treatment strategies. The basic mastitis control plan showed a median total cost of USD88.6/cow per year, which was close to the infected cows culling scenarios outputs. However, the segregation scenario was the most efficient, in which the total cost was reduced by about 50%. Such cost was more sensitive to probabilities and efficacy than the economic parameters. The model is flexible and can be customized by producers and veterinarians according to different control and herd settings.

Clinical disease incidence during early lactation, risk factors and association with fertility and culling in grazing dairy cows in Uruguay.

This paper aims to describe clinical disease incidence in early lactation and explore its association with fertility and culling in 13 commercial grazing dairy herds in Uruguay. Seven farms with less than 250 dairy cows considered small herds (SH) with a herd size average ± (SD) of 144 ± (56) cows and six farms with more than 500 cows considered large herds (LH) with a herd size average ± (SD) of 830 ± (239) cows were selected. Herd managers recorded health events during the first 90 days in milk in 5375 Holstein dairy cows [24.5% (n=1316) of them were primiparous cows, (PP)] during one year. Overall, 36.5% (n=1959) of the cows had at least one clinical health event between 1-90 days in milk. The cumulative incidences were 2.2% for twin birth and 4.9% for stillbirth. Cumulative incidence was 4.4% for retained placenta-metritis (RP-metritis), 27.6% for clinical mastitis and 5.0% for lameness. Our data showed that parity and herd size were risk factors for postpartum disease in grazing dairy herds. In PP cows, stillbirth incidence was higher than in multiparous (MP) cows (PP=6.9 ± 3.4, SD vs. MP=4.3 ± 2.6, SD), while in MP cows twin births (MP=2.7 ± 1.7, SD vs. PP=0.7 ± 2.7, SD), RP-metritis (MP=4.6 ± 3.9, SD vs. PP=3.8 ± 3.7, SD) and mastitis incidence (MP=30.9 ± 11.4, SD vs. PP=17.2 ± 13.9, SD) was higher. Clinical mastitis (LH=29.4 ± 9.6, SD vs. SH=19.1 ± 11.3, SD) and lameness incidence (LH=5.6 ± 1.9, SD vs. SH=2.3 ± 2.1, SD) was higher in large herds than in small herds. RP-metritis was increased by stillbirth (OR=4.4, 95 % CI=2.9-6.5) and twin birth (OR=2.8, 95 % CI=1.5-5.1). Diseases had a negative impact on time to first service and pregnancy rate and increased culling hazard rate. Disease incidence in early lactation was high and showed a wide variation among herds (10.4%-48.7%), which highlights the relevance of a herd health program prioritizing the early lactation disease control.

Heifer management characterization in dairy herds from the west of Buenos Aires, Argentina / Caracterização da gestão de novilhas em rebanhos leiteiros do oeste de Buenos Aires, Argentina

The replacement program in a dairy farm represents the second or third largest cost in a dairy operation. This study aimed to characterize and typify the practices related to the dairy heifer replacement program and describe the growth, development, and health parameters during this period in commercial dairy herds in Trenque Lauquen. A cross-sectional observational study was carried out, including 54 randomly selected dairy farms that were visited once to collect data about facilities and management through a semi-structured survey. Cluster and principal coordinates analysis were applied to classify the farms based on all variables collected, grouped in four main areas: pre-fresh cows, colostrum management, pre-weaning calf 's management, and personnel. Additionally, growth, development, and health status were also recorded and described for calves and breeding heifers. Two similar-sized farm clusters were identified with differences in management and facilities in different areas of calves rearing. In one cluster there was a greater proportion of farms having a pre-fresh group, implementing appropriate health (colostrum, vaccination) and feeding management. Also, differences in personnel and technical support were relevant. The estimated body gain was 452 and 774 g/d for calves younger or older than 60 d of age, respectively. The age and weight farm averages in breeding heifers were 21.0 mo (range: 16.7-27.5) and 416.3 kg (range: 336.7-519.3), respectively. Diarrhea and respiratory affections were the major problems in pre-weaning calves and heifer rearing, respectively. The median mortality was 7.3, 7.6, and 2.9% at the calving, pre-weaning, and heifer rearing period, respectively. The results showed an improvement opportunity for producers, the design of precise and high impact programs that could lead to an improved replacement program.(AU)

Nos rebanhos leiteiros, o programa de reposição representa o segundo ou o terceiro maior custo da atividade de produção de leite. O objetivo do presente trabalho foi caracterizar e tipificar as práticas relacionadas ao programa de reposição de novilhas leiteiras e descrever o crescimento, desenvolvimento e parâmetros de saúde durante este período em rebanhos leiteiros comerciais localizados em Trenque Lauquen, oeste de Buenos Aires, Argentina. Foi realizado um estudo observacional transversal incluindo 54 fazendas de produção de leite selecionadas ao acaso e visitadas uma única vez para a colheita de dados relacionados a instalações e manejo empregando-se um questionário semi-estruturado. Foi efetuada a análise dos agrupamentos e das coordenadas principais para classificar as fazendas com base em todas as variáveis colhidas e agrupadas em quatro principais áreas: vacas pré-parto, manejo de colostro, manejo pré-desmame de bezerros e recursos humanos. Os dados referentes ao crescimento, desenvolvimento e estado de saúde dos animais também foram registrados e descritos para bezerros e novilhas. Dois grupos de fazendas de tamanho semelhante foram identificados com diferenças no manejo e instalações em distintas áreas de recria de bezerros. Em um grupo houve uma maior proporção de fazendas que tinham um grupo de vacas pré-parto, com implementação de adequado manejo de saúde (colostro, vacinações) e manejo alimentar. Também foram relevantes as diferenças em termos de pessoal e suporte técnico. O ganho de peso estimado foi de 452 e 774 gramas por dia, respectivamente, para os bezerros jovens e os com idade superior a 60 dias. As médias das fazendas da idade e do peso das novilhas de reprodução foram, respectivamente, 21,0 meses (variação de 16,7 a 27,5) e 416,3 kg (variação de 336,7 a 519,3). A diarreia e as afecções respiratórias foram os maiores problemas de saúde, respectivamente, nos bezerros em pré-desmama e novilhas em recria. A média de mortalidade foi de 7,3; 7,6 e 2,9%, respectivamente, ao parto, na pré-desmama e durante a recria de novilhas. Os resultados obtidos demonstraram a existência de oportunidades de melhoria para os produtores, com o delineamento de programas precisos e de alto impacto que poderão propiciar um programa de reposição aprimorado.(AU)

Preference of veterinarians to select an udder health programme for milk producers.

BACKGROUND: This investigation was carried out to gain more insight about the preference of veterinarians on the implementation of an udder health programme (UHP) in a dairy farm. METHODS: A choice experiment was designed to elicit the preferences of the participants. The study population consisted of 36 veterinarians from Argentina specialised on milk quality. The choice experiment offered several UHPs, which were combinations of some of the interventions included in the so-called five-point plan. To reduce bias among the participants, the UHPs offered were unlabelled and considered two farm contexts: one was on a pasture system and the other was on a dry-lot with pasture access system. The basic criteria (the so-called attribute) to describe veterinarians' preferences for each UHP proposed were efficacy on clinical mastitis (CM) and bulk milk somatic cell count (BMSCC) reduction, cost and technical support. The data collected were analysed using conjoint analysis. RESULTS: UHP cost and UHP efficacy on BMSCC and CM had a significant influence on veterinarians' ranking decisions under both dairy production contexts. The efficacy on CM was the most important attribute to prefer a particular UHP, while technical assistance was the least important attribute considered. The attributes related to efficacy on both BMSCC and CM explained over 60 per cent of the total importance of all attributes. CONCLUSION: To the authors' knowledge, this is the first research in South America focused on studying veterinarians' preferences to suggest a UHP. The cost and efficacy attributes were the veterinarians' top priority attributes to decide the best UHP.

Metabolic predictors of peri-partum diseases and their association with parity in dairy cows.

The predictive values of plasma non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHB), cholesterol, albumin and calcium to predict risk of peripartum diseases in primiparous (PP) and multiparous (MP) Holstein cows was investigated. Besides it was assessed if the health status interacted with parity on body condition score and metabolic profiles during the transition period. Dairy cows (126 PP and 182 MP) from a commercial dairy free stall herd (loose-housing system) were weekly body condition scored and tail bled for metabolites determination from -3 to +4 weeks relative to calving. Peripartum diseases were diagnosed by a single trained veterinarian, while subclinical diseases (ketosis and hypocalcemia) were diagnosed at the laboratory. Cows were classified as healthy cows, cows with one event, or cows with two clinical events following a prospective observational cohort study, with only healthy cows enrolled at the beginning of the study. The largest incidence was for metritis (26.6%) followed by retained placenta (17.2%) and mastitis (15.2%) with no effect of parity, while subclinical hypocalcemia incidence was greater in MP than PP cows (43% vs 9.5%) respectively. In MP cows albumin concentrations were predictive for metritis at week -2 and for retained placenta at weeks -2 and -1, while cholesterol was predictive for mastitis at week -2, -1 and at calving. The interaction between health status and parity affected all metabolites during the transition period. This study showed a different evolution of metabolic profiles in healthy and sick cows during the transition according to parity, pointing out albumin and cholesterol as diseases predictors before calving.

Milking machine and udder health management factors associated with bulk milk somatic cell count in Uruguayan herds.

This paper describes the findings of static milking machine tests and milking observations on Uruguayan dairy farms. The aim of this study was to investigate the association between both milking machine performance and udder health management factors and bulk milk somatic cell count (BMSCC) in Uruguayan dairy herds. Data from 907 visits were used for the analysis. The farm visits were made between April 2006 and November 2015 and farms were located in 17 of the 19 departments of Uruguay. Each visit involved a short static machine test and observation of the milking process; the use of blanket dry cow therapy was also recorded. The BMSCC was the variable of interest. Univariable analysis was applied to explore the best set of predictors to be included in the multivariable model. A multivariable linear regression model was fitted. The median BMSCC over the years was 376 thousand cells/mL (interquartile range = 280,000-500,000 cells/mL). The final model showed a lower BMSCC for herds that used post-milking teat disinfection, applied the teat cups to dry teats and maintained the pulsation system in good working order. There was no significant association between BMSCC and blanket dry cow therapy in the final model. The association of these milking machine and udder health management factors with the BMSCC under Uruguayan conditions is relevant information for a dairy industry that needs low BMSCCs to compete on the world market.

Prevalence and antibiotic susceptibility of coagulase-negative Staphylococcus species from bovine subclinical mastitis in dairy herds in the central region of Argentina.

Coagulase-negative staphylococci (CNS) are a common cause of bovine subclinical mastitis (SCM). The prevalence of CNS species causing SCM identified by genotyping varies among countries. Overall, the antimicrobial resistance in this group of organisms is increasing worldwide; however, little information exists about a CNS species resistant to antibiotics. The aim of the present study was to genotypically characterize CNS at species level and to determine the prevalence and antibiotic resistance profiles of CNS species isolated from bovine SCM in 51 dairy herds located in the central region of the province of Cordoba, Argentina. In this study, we identified 219 CNS isolates at species level by PCR-restriction fragment length polymorphism of the groEL gene. Staphylococcus chromogenes (46.6%) and Staphylococcus haemolyticus (32%) were the most prevalent species. A minimum of three different CNS species were present in 41.2% of the herds. S. chromogenes was isolated from most of the herds (86.3%), whereas S. haemolyticus was isolated from 66.7% of them. The broth microdilution method was used to test in vitro antimicrobial susceptibility. Resistance to a single compound or two related compounds was expressed in 43.8% of the isolates. S. chromogenes and S. haemolyticus showed a very high proportion of isolates resistant to penicillin. Resistance to two or more non-related antimicrobials was found in 30.6% of all CNS. S. haemolyticus exhibited a higher frequency of resistance to two or more non-related antimicrobials than S. chromogenes.

Prevalencia y sensibilidad a antibióticos de especies de estafilococos coagulasa negativos provenientes de mastitis subclínica en bovinos de tambos de la región central de Argentina / Prevalence and antibiotic susceptibility of coagulase-negative Staphylococcus species from bovine subclinical mastitis in dairy herds in the central region of Argentina

Coagulase-negative staphylococci (CNS) are a common cause of bovine subclinical mastitis (SCM). The prevalence of CNS species causing SCM identified by genotyping varies among countries. Overall, the antimicrobial resistance in this group of organisms is increasing worldwide; however, little information exists about a CNS species resistant to antibiotics. The aim of the present study was to genotypically characterize CNS at species level and to determine the prevalence and antibiotic resistance profiles of CNS species isolated from bovine SCM in 51 dairy herds located in the central region of the province of Cordoba, Argentina. In this study, we identified 219 CNS isolates at species level by PCR-restriction fragment length polymorphism of the groEL gene. Staphylococcus chromogenes (46.6%) and Staphylococcus haemolyticus (32%) were the most prevalent species. A minimum of three different CNS species were present in 41.2% of the herds. S. chromogenes was isolated from most of the herds (86.3%), whereas S. haemolyticus was isolated from 66.7% of them. The broth microdilution method was used to test in vitro antimicrobial susceptibility. Resistance to a single compound or two related compounds was expressed in 43.8% of the isolates. S. chromogenes and S. haemolyticus showed a very high proportion of isolates resistant to penicillin. Resistance to two or more non-related antimicrobials was found in 30.6% of all CNS. S. haemolyticus exhibited a higher frequency of resistance to two or more non-related antimicrobials than S. chromogenes.

Los estafilococos coagulasa negativos (ECN) son una causa frecuente de mastitis subclínica (MSC) en bovinos. La prevalencia de especies de ECN causantes de MSC identificadas por métodos genotípicos varía entre países. La resistencia antimicrobiana en este grupo de organismos se está incrementando en el mundo; sin embargo, existe poca información acerca de las especies de ECN resistentes a antibióticos. Los objetivos del presente estudio fueron caracterizar genotípicamente los ECN a nivel de especie y determinar la prevalencia y los perfiles de resistencia a antibióticos de las especies de ECN aisladas de MSC en bovinos de 51 rodeos situados en la provincia de Córdoba, Argentina. Mediante polimorfismos de los fragmentos de restricción del gen groEL identificamos 219 aislamientos de ECN a nivel de especie. Staphylococcus chromogenes (46,6%) y Staphylococcus haemolyticus (32%) fueron las especies más prevalentes. Un mínimo de 3 especies diferentes de ECN estuvieron presentes en el 41,2% de los tambos. S. chromogenes fue aislado en la mayoría de los tambos (86,3%), mientras que S. haemolyticus fue aislado en el 66,7% de aquellos. Para el análisis de sensibilidad a los antimicrobianos in vitro se usó el método de microdilución en caldo. La resistencia a un único compuesto o a 2 compuestos relacionados fue expresada en el 43,8% de los aislamientos. S. chromogenes y S. haemolyticus mostraron una muy elevada proporción de aislamientos resistentes a penicilina. La resistencia a 2 o más antimicrobianos no relacionados fue hallada en el 30,6% de los ECN. S. haemolyticus exhibió una frecuencia de resistencia a 2 o más antimicrobianos no relacionados más elevada que S. chromogenes.

Molecular screening of pathogenic Escherichia coli strains isolated from dairy neonatal calves in Cordoba province, Argentina.

The aim of this study was to perform a current molecular characterization of bovine pathogenic Escherichia coli strains isolated from random samplings in Argentinean dairy farms. Rectal swabs were obtained from 395 (63.7%) healthy and 225 (36.3%) diarrheic calves, belonging to 45 dairy farms in Cordoba Province, Argentina. E. coli isolates were examined for virulence genes (f5, f41, f17, sta, stb, lt, eae, vt) using PCR and the prevalence of E. coli virulence profiles was spatially described in terms of spatial distribution. A total of 30.1% isolates were found to be positive for at least one of the virulence genes. Depending on the different gene combinations present, 11 virulence profiles were found. Most of the isolates analyzed had a single gene, and no combination of fimbrial and enterotoxin gene was predominant. There was no association between the frequency and distribution of E. coli virulence genes and calf health status. Most of the virulence profiles were compatible with ETEC strains and showed a homogeneous distribution over the sampled area. A clustering pattern for E. coli virulence profiles could not be recognized. This work provides updated information on the molecular characterization of pathogenic E. coli strains from dairy herds in Cordoba, Argentina. These findings would be important to formulate prevention programs and effective therapies for diarrhea in calves caused by E. coli.

Molecular screening of pathogenic Escherichia coli strains isolated from dairy neonatal calves in Cordoba province, Argentina / Detección molecular de cepas patógenas de Escherichia coli aisladas de terneros neonatos de tambo en la provincia de Córdoba, Argentina

The aim of this study was to perform a current molecular characterization of bovine pathogenic Escherichia coli strains isolated from random samplings in Argentinean dairy farms. Rectal swabs were obtained from 395 (63.7 %) healthy and 225 (36.3 %) diarrheic calves, belonging to 45 dairy farms in Cordoba Province, Argentina. E. coli isolates were examined for virulence genes (f5, f41, f17, sta, stb, lt, eae, vt) using PCR and the prevalence of E. coli virulence profiles was spatially described in terms of spatial distribution. A total of 30.1 % isolates were found to be positive for at least one of the virulence genes. Depending on the different gene combinations present, 11 virulence profiles were found. Most of the isolates analyzed had a single gene, and no combination of fimbrial and enterotoxin gene was predominant. There was no association between the frequency and distribution of E. coli virulence genes and calf health status. Most of the virulence profiles were compatible with ETEC strains and showed a homogeneous distribution over the sampled area. A clustering pattern for E. coli virulence profiles could not be recognized. This work provides updated information on the molecular characterization of pathogenic E. coli strains from dairy herds in Cordoba, Argentina. These findings would be important to formulate prevention programs and effective therapies for diarrhea in calves caused by E. coli.

El objetivo de este trabajo fue realizar una caracterización molecular actualizada de cepas patógenas bovinas de Escherichia coli aisladas de un muestreo aleatorio en tambos de una de las principales zonas lecheras de Argentina. Se obtuvieron hisopados rectales de 395 terneros neonatos sanos (63,7 %) y 225 diarreicos (36,3 %) pertenecientes a 45 tambos de la provincia de Córdoba, Argentina. Los genes de virulencia f5, f41, f17, sta, stb, lt, eae y vt se analizaron mediante PCR y se investigó la prevalencia de los perfiles de virulencia en función de la distribución geográfica. La prevalencia de aislamientos de E. coli patogénicos con al menos un gen de virulencia fue del 30,1 %. Once perfiles de virulencia fueron identificados, dependiendo de la combinación de genes presentes. La mayor parte de las muestras presentó un solo gen de virulencia, y no predominó ninguna combinación de genes de fimbrias y toxinas. No hubo asociación entre la frecuencia y la distribución de los genes de virulencia y el estado de salud de los terneros. La mayoría de los perfiles de virulencia fueron compatibles con cepas ECET y se distribuyeron cubriendo toda el área geográfica muestreada. No se reconoció ningún patrón de agrupamiento espacial para dichos perfiles. Este trabajo provee información actualizada sobre la caracterización molecular de E. coli patógena en rodeos lecheros de Córdoba, Argentina. Estos resultados serían importantes para formular programas preventivos y terapias eficaces contra la diarrea bovina causada por E. coli.

Molecular screening of pathogenic Escherichia coli strains isolated from dairy neonatal calves in Cordoba province, Argentina / Detección molecular de cepas patógenas de Escherichia coli aisladas de terneros neonatos de tambo en la provincia de Córdoba, Argentina

The aim of this study was to perform a current molecular characterization of bovine pathogenic Escherichia coli strains isolated from random samplings in Argentinean dairy farms. Rectal swabs were obtained from 395 (63.7 %) healthy and 225 (36.3 %) diarrheic calves, belonging to 45 dairy farms in Cordoba Province, Argentina. E. coli isolates were examined for virulence genes (f5, f41, f17, sta, stb, lt, eae, vt) using PCR and the prevalence of E. coli virulence profiles was spatially described in terms of spatial distribution. A total of 30.1 % isolates were found to be positive for at least one of the virulence genes. Depending on the different gene combinations present, 11 virulence profiles were found. Most of the isolates analyzed had a single gene, and no combination of fimbrial and enterotoxin gene was predominant. There was no association between the frequency and distribution of E. coli virulence genes and calf health status. Most of the virulence profiles were compatible with ETEC strains and showed a homogeneous distribution over the sampled area. A clustering pattern for E. coli virulence profiles could not be recognized. This work provides updated information on the molecular characterization of pathogenic E. coli strains from dairy herds in Cordoba, Argentina. These findings would be important to formulate prevention programs and effective therapies for diarrhea in calves caused by E. coli.(AU)

El objetivo de este trabajo fue realizar una caracterización molecular actualizada de cepas patógenas bovinas de Escherichia coli aisladas de un muestreo aleatorio en tambos de una de las principales zonas lecheras de Argentina. Se obtuvieron hisopados rectales de 395 terneros neonatos sanos (63,7 %) y 225 diarreicos (36,3 %) pertenecientes a 45 tambos de la provincia de Córdoba, Argentina. Los genes de virulencia f5, f41, f17, sta, stb, lt, eae y vt se analizaron mediante PCR y se investigó la prevalencia de los perfiles de virulencia en función de la distribución geográfica. La prevalencia de aislamientos de E. coli patogénicos con al menos un gen de virulencia fue del 30,1 %. Once perfiles de virulencia fueron identificados, dependiendo de la combinación de genes presentes. La mayor parte de las muestras presentó un solo gen de virulencia, y no predominó ninguna combinación de genes de fimbrias y toxinas. No hubo asociación entre la frecuencia y la distribución de los genes de virulencia y el estado de salud de los terneros. La mayoría de los perfiles de virulencia fueron compatibles con cepas ECET y se distribuyeron cubriendo toda el área geográfica muestreada. No se reconoció ningún patrón de agrupamiento espacial para dichos perfiles. Este trabajo provee información actualizada sobre la caracterización molecular de E. coli patógena en rodeos lecheros de Córdoba, Argentina. Estos resultados serían importantes para formular programas preventivos y terapias eficaces contra la diarrea bovina causada por E. coli.(AU)

Accuracy of the composite somatic cell count to detect intra-mammary infection in dairy cows using latent class analysis.

The somatic cell count (SCC) is considered an important indicator of intra-mammary infection (IMI). The purpose of this study was to determine the accuracy of both SCC and culture to detect IMI and their conditional dependence by means of latent class methods. This study involved 175 dairy cows from 2 herds with different udder infection prevalences. Quarter and composite milk samples were collected for SCC and bacteriological culture. Latent-class models using Bayesian methods were used to estimate test sensitivity (Se) and specificity (Sp) and population prevalence. The models ran involved only major mastitis pathogens and composite SCC (CSCC). Five thresholds between 100,000 and 300,000 cells/mL were evaluated and the receiver operating characteristics (ROC) curve analysis was performed. Fifty-five percent of the cows had CSCC ≥200,000 cells/mL and 95.4% of the cows had at least one infected quarter either with minor or major pathogens. Considering a threshold of 150,000 cells/mL, the estimated Se and Sp for the CSCC were, 0.80 (95% CrI 0.71-0.88) and 0.57 (95% CrI 0.44-0.71), respectively. The estimated culture Se and Sp were 0.83 (95% CrI 0.73-0.93) and 0.89 (95% CrI 0.74-0.98), respectively. There was no evidence of dependence between CSCC and culture. The area under curve for CSCC was 0.72. To the best of our knowledge, this is the first report of the CSCC accuracy to detect IMI for major pathogens considering the effect of culture misclassification. The estimates provided here could help to examine the performance of sampling schemes based on CSCC to manage udder health.

Lactic acid bacteria from raw milk as potentially beneficial strains to prevent bovine mastitis.

Bovine mastitis produces a wide variety of problems in the dairy farm. The treatment of this disease is based on the use of antibiotics which are not always effective. These drugs are also responsible for the presence of residues in the milk and the increase of antibiotic-resistant strains. Probiotic products were proposed as a valid alternative to antibiotic therapies and are also useful for the prevention of infectious syndromes. With the aim of designing a probiotic product to prevent bovine mastitis, lactic acid bacteria (LAB) were isolated from foremilk samples from different dairy farms in Córdoba-Argentina. One hundred and seventeen LAB were isolated and their beneficial characteristics such as the production of inhibitory substances, surface properties and production of exopolysaccharides (EPS) were assessed. Most of them displayed low degree of hydrophobicity, autoaggregation, EPS negative phenotype and were identified as Enterococcus hirae and Pediococcus pentosaceus. Nine LAB strains inhibited three indicator bacteria. Some isolates were pre-selected and genetically identified according to the results obtained. Antibiotic resistance and virulence factors were studied for the assessment of the safety of the strains. The results obtained were compared to those reported previously from samples obtained in the North-western area of the country and some differences were found.

Development of an experimentally induced Streptococcus uberis subclinical mastitis in goats.

Streptococcus uberis is a major environmental mastitis-causing pathogen. The infections are predominantly subclinical and are frequently undetected and untreated for extended periods of time. More information about the pathogenesis of S. uberis mastitis would be useful. To our knowledge, no experimental studies into the mastitis pathogenesis caused by S. uberis have been described in lactating goats. The aim of this study was to reproduce an experimentally induced S. uberis subclinical mastitis in lactating goats aimed to evaluate the inflammatory response, dynamics of infection and the pathological findings within the first hours of intramammary inoculation with S. uberis. Six Saanen goats in mid-lactation were inoculated with 1.7 × 10(8)cfu of S. uberis. Bacterial growth peaked in milk from challenged right mammary halves (RMH) at 4h PI. Shedding of viable bacteria showed a marked decrease at 20 h PI. Mean somatic cell counts in milk from the RMH peaked at 20 h PI. Inoculation with S. uberis was followed by a decrease in the mean total number of leukocytes. Signs and systemic symptoms were not evoked by intramammary inoculation. S. uberis could be isolated in tissue from all RMH. Histological examination of specimens of the RMH and lymph nodes of the goats showed an increased inflammatory response throughout the experiment. The histological findings correlated with the immunohistochemical detection of S. uberis in RMH. In conclusion, the experimental inoculation of S. uberis in lactating goats is capable of eliciting an inflammatory response and causing pathological changes, resulting in a subclinical mastitis. This investigation shows that goat might to represent a valuable model for the study of the mastitis pathogenesis caused by S. uberis.

[Microbiological quality of the water used in a random sample from dairy farms in Córdoba, Argentina]. / Calidad microbiológica del agua utilizada en establecimientos lecheros de la zona de Villa María (Córdoba).

Bacteriological contamination of well water and wash water in a random sample obtained from 50 farms from Villa María (Córdoba) dairy area, Argentina, was evaluated during a visit in 2007. Forty six percent and 24 % of farms showed an aerobic mesophilic bacteria count higher than 500 CFU/ml in wash water and well water, respectively. Escherichia coli was isolated in 20 % of samples from both sources. Pseudomonas aeruginosa showed high frequency of isolation in well water (36 %) and wash water (42 %). Eighty and eighty-eight percent of dairy farms have contaminated well water and wash water, respectively. The findings show moderate concordance between contamination of well water and wash water for mesophilic aerobics and total coliforms. The results reveal that a high percentage of dairy farms in the basin under study have poor bacteriological water quality, not suitable for milking and washing facilities.

Prevalence of Cryptosporidium spp. and Giardia spp., spatial clustering and patterns of shedding in dairy calves from Córdoba, Argentina.

The objectives of this study were to estimate calf and herd prevalence of Cryptosporidium spp. and Giardia spp., the herd prevalence clustering, spatial distribution according to soil type and shedding patterns in dairy calves from Cordoba, Argentina. Six hundred twenty calves younger than 7 weeks of age from 43 dairy herds were sampled. Samples were processed with the formol-ether and modified Ziehl-Neelsen techniques. Univariate analysis and Kruskall-Wallis tests were used. Factors associated were subjected to multivariate analysis with calf shedding intensity as the response variable. Clustering of herd prevalence was assessed by a scan method, and spatial analysis was applied to explore the overlapping of high prevalence herds and soil type. Overall calf prevalence for Cryptosporidium spp. oocysts and Giardia spp. cysts were 19.35% (95% CI: 16.14; 22.54) and 34.50% (95% CI: 30.69; 38.34), respectively. Calves younger than two weeks of age were almost four times more likely to be infected with Cryptosporidium, in comparison to older ones (RR: 3.78, 95% CI: 2.27; 6.26). Giardia spp. shedding showed a similar age pattern (RR: 1.33, 95% CI: 1.02; 1.75). A primary cluster of high Cryptosporidium prevalence was found, and high prevalence herds were located in areas with poor drained soil.

Calidad microbiológica del agua utilizada en establecimientos lecheros de la zona de Villa María (Córdoba) / Microbiological quality of the water used in a random sample from dairy farms in Córdoba, Argentina

Se evaluó la calidad bacteriológica del agua de pozo y del agua de lavado en una muestra aleatoria de 50 tambos distribuidos en la cuenca lechera de Villa María (Córdoba), Argentina. La visita a los tambos se realizó en 2007. Un 46 % y un 24 % de los tambos presentaron recuentos de aerobios mesófilos superiores a 500 UFC/ml en el agua de lavado y en el agua de pozo, respectivamente. En un 20 % de los establecimientos se aisló Escherichia coli de ambas fuentes de agua. Pseudomonas aeruginosa registró una alta frecuencia de aislamiento en el agua de pozo (36 %) y en la de lavado (42 %). Un 80 % y un 88 % de los establecimientos contaban con agua de pozo y de lavado no aptas, respectivamente. Los niveles de mesófilos aerobios y de coliformes totales presentes en el agua de pozo mostraron una concordancia moderada con los detectados en el agua destinada al lavado. En virtud de estos resultados, puede afirmarse que un elevado porcentaje de los tambos ubicados en la cuenca lechera de Villa María emplean agua de calidad bacteriológica deficiente, no apta para el ordeño ni el lavado de las instalaciones.

Bacteriological contamination of well water and wash water in a random sample obtained from 50 farms from Villa María (Córdoba) dairy area, Argentina, was evaluated during a visit in 2007. Forty six percent and 24 % of farms showed an aerobic mesophilic bacteria count higher than 500 CFU/ml in wash water and well water, respectively. Escherichia coli was isolated in 20 % of samples from both sources. Pseudomonas aeruginosa showed high frequency of isolation in well water (36 %) and wash water (42 %). Eighty and eighty-eight percent of dairy farms have contaminated well water and wash water, respectively. The findings show moderate concordance between contamination of well water and wash water for mesophilic aerobics and total coliforms. The results reveal that a high percentage of dairy farms in the basin under study have poor bacteriological water quality, not suitable for milking and washing facilities.

Prevalence of Cryptosporidium spp. and Giardia spp., spatial clustering and patterns of shedding in dairy calves from Córdoba, Argentina / Prevalência de Cryptosporidium spp. e Giardia spp., distribuição espacial e padrões de eliminação em bezerros de propriedades leiteiras em Córdoba, Argentina

The objectives of this study were to estimate calf and herd prevalence of Cryptosporidium spp. and Giardia spp., the herd prevalence clustering, spatial distribution according to soil type and shedding patterns in dairy calves from Cordoba, Argentina. Six hundred twenty calves younger than 7 weeks of age from 43 dairy herds were sampled. Samples were processed with the formol-ether and modified Ziehl-Neelsen techniques. Univariate analysis and Kruskall-Wallis tests were used. Factors associated were subjected to multivariate analysis with calf shedding intensity as the response variable. Clustering of herd prevalence was assessed by a scan method, and spatial analysis was applied to explore the overlapping of high prevalence herds and soil type. Overall calf prevalence for Cryptosporidium spp. oocysts and Giardia spp. cysts were 19.35 percent (95 percent CI: 16.14; 22.54) and 34.50 percent (95 percent CI: 30.69; 38.34), respectively. Calves younger than two weeks of age were almost four times more likely to be infected with Cryptosporidium, in comparison to older ones (RR: 3.78, 95 percent CI: 2.27; 6.26). Giardia spp. shedding showed a similar age pattern (RR: 1.33, 95 percent CI: 1.02; 1.75). A primary cluster of high Cryptosporidium prevalence was found, and high prevalence herds were located in areas with poor drained soil.

Os objetivos deste estudo foram determinar a prevalência de Cryptosporidium spp. e Giardia spp., a presença de aglomerados, a distribuição espacial de acordo com o tipo de solo e padrões de eliminação de cistos e oocistos em bezerros de propriedades leiteiras em Córdoba, Argentina. Amostras fecais foram colhidas de 620 bezerros com menos de sete semanas de idade, provenientes de 43 propriedades leiteiras e examinadas pelas técnicas de formol-éter e Ziehl-Neelsen modificada. Foram realizadas uma análise univariada e o teste de Kruskal-Wallis e, em seguida, uma análise multivariada com a intensidade de eliminação de cistos e oocistos, como um evento. A presença de aglomerados foi determinada com o método de varredura e a análise espacial foi realizada para explorar a sobreposição de rebanhos com alta prevalência e tipo de solo. A prevalência de Cryptosporidium spp. e Giardia spp. foi de 19,35 por cento (IC 95 por cento: 16,14; 22,54) e 34,50 por cento (IC 95 por cento: 30,69; 38,34), respectivamente. A probabilidade de infecção por Cryptosporidium spp. foi quase quatro vezes maior para bezerros com menos de 2 semanas em comparação com os bezerros mais velhos (RR: 3,78, IC 95 por cento 2,27; 6,26). O mesmo padrão de infecção relacionada à idade foi observado para Giardia spp. (RR: 1,33, IC 95 por cento 1,02; 1,75). Foi encontrado um aglomerado primário com alta prevalência de Cryptosporidium spp., e rebanhos com alta prevalência foram localizados em solos mal drenados.

Seasonal variation of parasitism in pejerey Odontesthes bonariensis (Atheriniformes, Atherinopsidae) from La Viña reservoir (Córdoba, Argentina).

The pejerrey Odontesthes bonariensis is the most important freshwater fish of Argentina central region. The present study was conducted to describe the seasonal variation of parasitism in O. bonariensis from La Viña reservoir (31 degrees 17'S, 65 degrees 01'W), located in the province of Córdoba, Argentina. Between years 1999 and 2002, 573 fishes were caught, and their parasite infection and relative weight (Wr) were assesed. Three parasites were found, Lernaea cyprinacea (Crustacea), Contracaecum spp. larvae (Nematoda) and Cangatiella macdonaghi (Cestoda). Overall, Contracaecum spp. prevalence and intensity were very low. Lernaea cyprinacea and Cangatiella macdonaghi prevalences increased during summer and spring (P < 0.01), respectively. Lernaea cyprinacea infection showed also seasonal differences in intensity (P < 0.05), as well as C. macdonaghi regarding parasites density (P < 0.01). Cangatiella macdonaghi average parasites density was 32.0 (+/-22.5) cestodes per cm(3)of digestive content. No association between parasitism and fish relative weight was found. Besides the seasonality variations observed, the parasite burden found did not compromise fish body condition.

Seasonal variation of parasitism in pejerrey Odontesthes bonariensis (Atheriniformes, Atherinopsidae) from La Viña reservoir (Córdoba, Argentina) / Variação sazonal do parasitismo em Peixe-rei Odontesthes bonariensis (Atheriniformes, Atherinopsidae) no reservatório La Viña, Córdoba, Argentina

The pejerrey Odontesthes bonariensis is the most important freshwater fish of Argentina central region. The present study was conducted to describe the seasonal variation of parasitism in O. bonariensis from La Viña reservoir (31º 17'S, 65º 01'W), located in the province of Córdoba, Argentina. Between years 1999 and 2002, 573 fishes were caught, and their parasite infection and relative weight (Wr) were assesed. Three parasites were found, Lernaea cyprinacea (Crustacea), Contracaecum spp. larvae (Nematoda) and Cangatiella macdonaghi (Cestoda). Overall, Contracaecum spp. prevalence and intensity were very low. Lernaea cyprinacea and Cangatiella macdonaghi prevalences increased during summer and spring (P < 0.01), respectively. Lernaea cyprinacea infection showed also seasonal differences in intensity (P < 0.05), as well as C. macdonaghi regarding parasites density (P < 0.01). Cangatiella macdonaghi average parasites density was 32.0 (±22.5) cestodes per cm³ of digestive content. No association between parasitism and fish relative weight was found. Besides the seasonality variations observed, the parasite burden found did not compromise fish body condition.

O peixe rei Odontesthes bonariensis é um peixe de água doce de grande importância na região central da Argentina. O objetivo deste trabalho foi descrever a sazonalidade do parasitismo de O. bonariensis no reservatrio La Viña (31º 17'S, 65º 01'W), província de Córdoba, Argentina. Durante os anos 1999 e 2002 foram capturados 573 peixes. Nestes se fez à avaliação da condição corporal usando como parâmetro o peso relativo e identificaram-se os seguintes parasitos: Lernaea cyprinacea (Crustacea), Contracaecum spp. (Nematoda) e Cangatiella macdonaghi (Cestoda). As prevalências e intensidades de Contracaecum spp. foram muito baixas. Houve diferenças nas prevalências de L. cyprinacea e C. macdonaghi na época do ano (P < 0,01), sendo maiores no verão e na primavera, respectivamente. Houve diferenças estacionais na intensidade de L. cyprinacea (P < 0,05) e na densidade de C. macdonaghi (P < 0,01), neste ultimo alcançou-se um valor máximo nas amostras de 32,0 (±22,5) parasitos por cm³ de conteúdo digestivo. Não houve associação entre o parasitismo e o peso relativo dos peixes. Embora haja certa sazonalidade, as diferentes cargas parasitárias encontradas nâo prejudicam a saúde de O. bonariensis enquanto sua condição corporal.