In the Metropolitana region of Chile there are 3836 backyard production systems (BPS), characterized as small-scale systems. They act as a source of zoonotic pathogens, such as Salmonella enterica and Shiga toxin-producing Escherichia coli (STEC), whose prevalence in BPS has not been fully described. The objective of this study was to determine the positivity for both agents in BPS and to establish the risk factors related to their presence. In each BPS, an epidemiological survey was undertaken, and stool samples were collected to detect these pathogens via bacteriological culture and conventional PCR techniques. Subsequently, multivariable logistic regression models were applied to establish the risk factors associated with their presence. BPS positivity rates of 11.76% for STEC and 4.7% for S. enterica were observed. The systems showed poor welfare standards and a lack of biosecurity measures. The risk factor analysis concluded that the Gini–Simpson index (p = 0.030; OR = 1.717) and the presence of neighboring intensive poultry or swine production systems (p = 0.019; OR = 20.645) act as factors that increased the risk of positivity with respect to STEC. In the case of S. enterica, exchanging embryonated eggs (p = 0.021; OR = 39) and the presence of debeaked chickens (p = 0.001; OR = 156) were determined as factors that increased the risk of positivity for this agent. For positivity with respect to both pathogens, the Gini–Simpson index (p = 0.030; OR = 1.544) and being INDAP/PRODESAL users (p = 0.023; OR = 15.026) were determined as factors that increased the risk, whereas the type of confinement (p = 0.002; OR = 0.019) decreased it. Epidemiological surveillance of these neglected populations is lacking, highlighting the fact that STEC and S. enterica maintenance on BPS represents a potential threat to public health.

Patagonia in the far south of Chile is used as a breeding ground for cattle, which are then transported north for their final stages of growth before being killed for meat. The objective of this study was to compare mortality in beef cattle exposed to two different types of long-distance transport: by ship, using a roll-on/roll-off system, or by truck. Data from a major transport company were used to compare the mortality risks for calves and older cattle when conveyed by sea or road from southern to central Chile journeys of four and two days, respectively. Mortality was higher for both calves and older cattle traveling by sea than those traveling by road, but when the data was corrected for journey duration, mortality/day was greater for those traveling by road. Mortality was increased at high stocking densities and, for older cattle, winter was a high-risk season, compared with summer. Mortality was also higher for calves than older cattle. The results identify the greatest risks of mortality over the two routes to facilitate reform of the transport processes so that cattle welfare is improved.

Backyard production systems (BPS) are distributed worldwide, rearing animals recognized as reservoirs of Salmonella enterica and Shiga toxin-producing Escherichia coli (STEC), both zoonotic pathogens. The aim of this study was to characterize isolates of both pathogens obtained from animals raised in BPS from two central Chile regions. The presence of pathogens was determined by bacterial culture and confirmatory PCR for each sampled BPS, calculating positivity rates. Multivariate logistic regression was used to determine risk factors. Additionally, phenotypic antimicrobial resistance was determined. A positivity rate of 2.88% for S. enterica and 14.39% for STEC was determined for the complete study region (Valparaíso and Metropolitana regions). Risk factor analysis suggests that the presence of ruminants (OR = 1.03; 95% CI = 1.002–1.075) increases the risk of STEC-positive BPS, and the presence of ruminants (OR = 1.05; 95% CI = 1.002–1.075) and the animal handlers being exclusively women (OR = 3.54; 95% CI = 1.029–12.193) increase the risk for S. enterica/STEC positivity. Eighty percent of S. enterica isolates were multidrug resistant, and all STEC were resistant to Cephalexin. This study evidences the circulation of multidrug-resistant zoonotic bacterial strains in animals kept in BPS and the presence of factors that modify the risk of BPS positivity for both pathogens.

The objective of this study was to investigate the effect of a fine needle liver biopsy (FNB) on the behavior and milk production of postpartum dairy cows during and after the procedure. In Experiment 1, cows at 10 ± 1.1 days in milk were assigned to receive either a FNB (n = 26), involving collection of a liver sample using an 18G spinal needle under local anesthesia, or a sham procedure (n = 26). Behavioral responses during the procedure, such as vocalizations, kicking, and abrupt movements, were recorded and analyzed by a trained observer. In Experiment 2, a separate group of cows (n = 48), also at 10 ± 1.1 days in milk, underwent a FNB, and their daily lying behavior, rumination, and milk yield were monitored using automated sensors over three consecutive days: the day before (day -1, baseline), the day of (day 0), and the day after the procedure (day +1). No significant differences were observed in the behavioral responses between cows that received FNB and those that underwent the sham procedure. Post-procedure, daily lying time, rumination time, and milk yield remained stable compared to baseline values. On day +1, an increase in the number of lying bouts and a decrease in bout duration were noted. The results of this study indicate that liver FNB has little immediate or short-term effect on behavior or milk production, suggesting that it is a minimally painful procedure, supporting its suitability for clinical and research applications.

The aim of this study was to evaluate the relationship between cows’ hepatic lipid content (HLC) at 10 days in milk (DIM) and their metabolic status, health, and production during transition and early lactation periods. HLC was determined in 103 cows from a grazing Chilean dairy herd via cytologic examination of the liver through fine needle biopsies, categorized as mild, moderate, or severe. Blood metabolites were evaluated in the transition period, together with diseases in the postpartum period and milk production during the first 90 DIM. In pre-partum and postpartum periods, primiparous cows with severe HLC showed higher plasma cholesterol than multiparous cows with mild HLC. Postpartum, cows with severe HLC had higher serum non-esterified fatty acids (NEFAs) and NEFA/cholesterol ratios than those with mild HLC. Similarly, cows with moderate and severe HLC presented higher plasma β-hydroxybutyrate and greater risk of subclinical ketosis than cows with mild HLC. Additionally, cows with severe HLC had higher milk production and lower milk protein content than those with mild HLC. These results indicate that moderate to severe HLC at 10 DIM was associated with negative energy balance and subclinical ketosis, whereas severe HLC was associated with increased milk production and decreased milk protein content.