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BackgroundUnderstanding the effects of herd management practices on the prevalence of multidrug-resistant pathogenic Salmonella and commensals Enterococcus spp. and Escherichia coli in dairy cattle is key in reducing antibacterial resistant infections in humans originating from food animals. Our objective was to explore the herd and cow level features associated with the multi-drug resistant, and resistance phenotypes shared between Salmonella, E. coli and Enterococcus spp. using machine learning algorithms.MethodsRandomly collected fecal samples from cull dairy cows from six dairy farms in central California were tested for multi-drug resistance phenotypes of Salmonella, E. coli and Enterococcus spp. Using data on herd management practices collected from a questionnaire, we built three machine learning algorithms (decision tree classifier, random forest, and gradient boosting decision trees) to predict the cows shedding multidrug-resistant Salmonella and commensal bacteria.ResultsThe decision tree classifier identified rolling herd average milk production as an important feature for predicting fecal shedding of multi-drug resistance in Salmonella or commensal bacteria. The number of culled animals, monthly culling frequency and percentage, herd size, and proportion of Holstein cows in the herd were found to be influential herd characteristics predicting fecal shedding of multidrug-resistant phenotypes based on random forest models for Salmonella and commensal bacteria. Gradient boosting models showed that higher culling frequency and monthly culling percentages were associated with fecal shedding of multidrug resistant Salmonella or commensal bacteria. In contrast, an overall increase in the number of culled animals on a culling day showed a negative trend with classifying a cow as shedding multidrug-resistant bacteria. Increasing rolling herd average milk production and spring season were positively associated with fecal shedding of multidrug- resistant Salmonella

BackgroundUnderstanding the effects of herd management practices on the prevalence of multidrug-resistant pathogenic Salmonella and commensals Enterococcus spp. and Escherichia coli in dairy cattle is key in reducing antibacterial resistant infections in humans originating from food animals. Our objective was to explore the herd and cow level features associated with the multi-drug resistant, and resistance phenotypes shared between Salmonella, E. coli and Enterococcus spp. using machine learning algorithms.MethodsRandomly collected fecal samples from cull dairy cows from six dairy farms in central California were tested for multi-drug resistance phenotypes of Salmonella, E. coli and Enterococcus spp. Using data on herd management practices collected from a questionnaire, we built three machine learning algorithms (decision tree classifier, random forest, and gradient boosting decision trees) to predict the cows shedding multidrug-resistant Salmonella and commensal bacteria.ResultsThe decision tree classifier identified rolling herd average milk production as an important feature for predicting fecal shedding of multi-drug resistance in Salmonella or commensal bacteria. The number of culled animals, monthly culling frequency and percentage, herd size, and proportion of Holstein cows in the herd were found to be influential herd characteristics predicting fecal shedding of multidrug-resistant phenotypes based on random forest models for Salmonella and commensal bacteria. Gradient boosting models showed that higher culling frequency and monthly culling percentages were associated with fecal shedding of multidrug resistant Salmonella or commensal bacteria. In contrast, an overall increase in the number of culled animals on a culling day showed a negative trend with classifying a cow as shedding multidrug-resistant bacteria. Increasing rolling herd average milk production and spring season were positively associated with fecal shedding of multidrug- resistant Salmonella

BackgroundIn this study cull dairy cows from six California dairy herds were sampled seasonally over the course of a year. The objectives were to determine the prevalence of antimicrobial resistant (AMR) Salmonella spp. shed in cull cow feces, and the factors associated with fecal shedding of AMR and multidrug resistant (MDR) Salmonella.MethodsSix dairy farms located in the San Joaquin Valley of California were identified and enrolled as a convenience sample. On each dairy, and once during each of the four seasons, 10 cull cows were randomly selected for fecal sampling on the day of their removal from the herd. In addition, study personnel completed a survey based on responses of the herd manager to questions related to the previous 4 month's herd management and the specific cattle sampled. Fecal samples were submitted to the California Animal Health and Food Safety laboratory for Salmonella isolation. Antimicrobial resistance was evaluated using broth microdilution method and a gram-negative assay plate following Clinical Laboratory Standards Institute (CLSI) guidelines and breakpoint references. All statistical models were survey adjusted for number of animals on sampling day.ResultsA total of 62 Salmonella were isolated from 60 of the 239 fecal samples collected. For 12% (95% confidence interval (CI) [3-20]) of fecal samples a multidrug resistant Salmonella was isolated. The survey-weighted results for the two most common drug classes for which isolates were resistant were tetracycline (39%; 95% CI [27-51]) and ampicillin (18%; 95% CI [9-27]). An important finding was the identification of cephalosporin as the third most common drug class for which isolates were resistant, with ceftriaxone (10%; 95% CI [2-17]) being the most common drug associated with resistance in that class. At the cow-level, reason for culling, prior treatment with antimicrobial drugs as the reason for culling was associated with higher odds of isolating an AMR Salmonella isolate. At the herd

BackgroundIn this study cull dairy cows from six California dairy herds were sampled seasonally over the course of a year. The objectives were to determine the prevalence of antimicrobial resistant (AMR) Salmonella spp. shed in cull cow feces, and the factors associated with fecal shedding of AMR and multidrug resistant (MDR) Salmonella.MethodsSix dairy farms located in the San Joaquin Valley of California were identified and enrolled as a convenience sample. On each dairy, and once during each of the four seasons, 10 cull cows were randomly selected for fecal sampling on the day of their removal from the herd. In addition, study personnel completed a survey based on responses of the herd manager to questions related to the previous 4 month's herd management and the specific cattle sampled. Fecal samples were submitted to the California Animal Health and Food Safety laboratory for Salmonella isolation. Antimicrobial resistance was evaluated using broth microdilution method and a gram-negative assay plate following Clinical Laboratory Standards Institute (CLSI) guidelines and breakpoint references. All statistical models were survey adjusted for number of animals on sampling day.ResultsA total of 62 Salmonella were isolated from 60 of the 239 fecal samples collected. For 12% (95% confidence interval (CI) [3-20]) of fecal samples a multidrug resistant Salmonella was isolated. The survey-weighted results for the two most common drug classes for which isolates were resistant were tetracycline (39%; 95% CI [27-51]) and ampicillin (18%; 95% CI [9-27]). An important finding was the identification of cephalosporin as the third most common drug class for which isolates were resistant, with ceftriaxone (10%; 95% CI [2-17]) being the most common drug associated with resistance in that class. At the cow-level, reason for culling, prior treatment with antimicrobial drugs as the reason for culling was associated with higher odds of isolating an AMR Salmonella isolate. At the herd

The present work was undertaken to compare the commercial carcass quality and the fatty acid composition of subcutaneous fat from Friesian culled cows of over 30 months of age, and calves of 12 months of age from Pirenaica and Salers breeds slaughtered in a commercial abattoir in the Basque Country. Friesian culled cows provided lighter carcasses (p<0.05), although similar to calves from Pirenaica breed, with lower conformation (p<0.001) and less fat cover (p<0.01) compared to other groups of calves. The subcutaneous fat of culled cows provided higher content of saturated (p<0.001) and branched-chain fatty acids (p<0,05), and lower content of monounsa-turated (p<0.01) and polyunsaturated fatty acids (p<0,001) compared to calves from Pirenaica and Salers breeds. The percentage of trans-monounsaturated fatty acids was significantly higher in the subcutaneous fat of calves from Pirenaica breed (p<0.001), while the 10 t-18:1 content was significantly higher in the fat of calves from Pirenaica breed, intermediate in the fat of calves from Salers breed, and lower in the fat of culled cows (p<0.001). These provided a 10t/11t ratio <1 and a healthier relative trans-18:1 and conjugated linoleic acid isomeric profile in the fat of Friesian culled cows compared to other groups of calves, which may provide culled cow carcasses with a higher added value from the commercialization point of view and of the profitability of cattle farms in the Basque Country., Este trabajo se ha llevado a cabo con el objetivo de comparar la calidad comercial de la canal y la composición de ácidos grasos de la grasa subcutánea de vacas de desvieje de raza Frisona de más de 30 meses de edad, y de terneros de 12 meses de edad de las razas Pirenaica y Salers sacrificados en un matadero comercial de la Comunidad Autónoma del País Vasco. Las vacas de raza Frisona presentaron canales de menor peso (p<0,05), aunque similar al grupo de los terneros de raza Pirenaica y menor conformación (p<0,001) y estado de engrasamiento (p<0,01) en comparación con los grupos de terneros. La grasa subcutánea de las vacas de desvieje presentó un mayor contenido de ácidos grasos saturados (p<0,001) y ramificados (p<0,05), y un menor contenido de ácidos grasos monoinsaturados (p<0,01) y poliinsaturados (p<0,001) en comparación con la de los terneros de las razas Pirenaica y Salers. El porcentaje de ácidos grasos monoinsaturados de tipo trans fue significativamente superior en la grasa subcutánea de los terneros de raza Pirenaica (p<0,001), mientras que el contenido de 10t-18:1 fue significativamente mayor en la grasa de terneros de raza Pirenaica, intermedio en la grasa de terneros de raza Salers, y menor en la grasa de las vacas de desvieje (p<0,001). Esto dio lugar a una relación 10t/11t <1 y un perfil isomérico relativo de trans-18:1 y ácidos linoleico conjugados más saludable en la grasa de las vacas de desvieje de raza Frisona en comparación con los grupos de terneros. Esta idea podría contribuir a la valorización de las canales procedentes de vacas de desvieje desde el punto de vista de su comercialización y de la rentabilidad de las explotaciones ganaderas de vacuno en la Comunidad Autónoma del País Vasco.

The present work was undertaken to compare the commercial carcass quality and the fatty acid composition of subcutaneous fat from Friesian culled cows of over 30 months of age, and calves of 12 months of age from Pirenaica and Salers breeds slaughtered in a commercial abattoir in the Basque Country. Friesian culled cows provided lighter carcasses (p<0.05), although similar to calves from Pirenaica breed, with lower conformation (p<0.001) and less fat cover (p<0.01) compared to other groups of calves. The subcutaneous fat of culled cows provided higher content of saturated (p<0.001) and branched-chain fatty acids (p<0,05), and lower content of monounsa-turated (p<0.01) and polyunsaturated fatty acids (p<0,001) compared to calves from Pirenaica and Salers breeds. The percentage of trans-monounsaturated fatty acids was significantly higher in the subcutaneous fat of calves from Pirenaica breed (p<0.001), while the 10 t-18:1 content was significantly higher in the fat of calves from Pirenaica breed, intermediate in the fat of calves from Salers breed, and lower in the fat of culled cows (p<0.001). These provided a 10t/11t ratio <1 and a healthier relative trans-18:1 and conjugated linoleic acid isomeric profile in the fat of Friesian culled cows compared to other groups of calves, which may provide culled cow carcasses with a higher added value from the commercialization point of view and of the profitability of cattle farms in the Basque Country., Este trabajo se ha llevado a cabo con el objetivo de comparar la calidad comercial de la canal y la composición de ácidos grasos de la grasa subcutánea de vacas de desvieje de raza Frisona de más de 30 meses de edad, y de terneros de 12 meses de edad de las razas Pirenaica y Salers sacrificados en un matadero comercial de la Comunidad Autónoma del País Vasco. Las vacas de raza Frisona presentaron canales de menor peso (p<0,05), aunque similar al grupo de los terneros de raza Pirenaica y menor conformación (p<0,001) y estado de engrasamiento (p<0,01) en comparación con los grupos de terneros. La grasa subcutánea de las vacas de desvieje presentó un mayor contenido de ácidos grasos saturados (p<0,001) y ramificados (p<0,05), y un menor contenido de ácidos grasos monoinsaturados (p<0,01) y poliinsaturados (p<0,001) en comparación con la de los terneros de las razas Pirenaica y Salers. El porcentaje de ácidos grasos monoinsaturados de tipo trans fue significativamente superior en la grasa subcutánea de los terneros de raza Pirenaica (p<0,001), mientras que el contenido de 10t-18:1 fue significativamente mayor en la grasa de terneros de raza Pirenaica, intermedio en la grasa de terneros de raza Salers, y menor en la grasa de las vacas de desvieje (p<0,001). Esto dio lugar a una relación 10t/11t <1 y un perfil isomérico relativo de trans-18:1 y ácidos linoleico conjugados más saludable en la grasa de las vacas de desvieje de raza Frisona en comparación con los grupos de terneros. Esta idea podría contribuir a la valorización de las canales procedentes de vacas de desvieje desde el punto de vista de su comercialización y de la rentabilidad de las explotaciones ganaderas de vacuno en la Comunidad Autónoma del País Vasco.