Genomic Epidemiology of Salmonella enterica Circulating in Surface Waters Used in Agriculture and Aquaculture in Central Mexico.

Salmonella enterica can survive in surface waters (SuWa), and the role of nonhost environments in its transmission has acquired increasing relevance. In this study, we conducted comparative genomic analyses of 172 S. enterica isolates collected from SuWa across 3 months in six states of central Mexico during 2019. S. enterica transmission dynamics were assessed using 87 experimental and 112 public isolates from Mexico collected during 2002 through 2019. We also studied genetic relatedness between SuWa isolates and human clinical strains collected in North America during 2005 through 2020. Among experimental isolates, we identified 41 S. enterica serovars and 56 multilocus sequence types (STs). Predominant serovars were Senftenberg (n = 13), Meleagridis, Agona, and Newport (n = 12 each), Give (n = 10), Anatum (n = 8), Adelaide (n = 7), and Infantis, Mbandaka, Ohio, and Typhimurium (n = 6 each). We observed a high genetic diversity in the sample under study, as well as clonal dissemination of strains across distant regions. Some of these strains are epidemiologically important (ST14, ST45, ST118, ST132, ST198, and ST213) and were genotypically close to those involved in clinical cases in North America. Transmission network analysis suggests that SuWa are a relevant source of S. enterica (0.7 source/hub ratio) and contribute to its dissemination as isolates from varied sources and clinical cases have SuWa isolates as common ancestors. Overall, the study shows that SuWa act as reservoirs of various S. enterica serovars of public health significance. Further research is needed to better understand the mechanisms involved in SuWa contamination by S. enterica, as well as to develop interventions to contain its dissemination in food production settings. IMPORTANCE Surface waters are heavily used in food production worldwide. Several human pathogens can survive in these waters for long periods and disseminate to food production environments, contaminating our food supply. One of these pathogens is Salmonella enterica, a leading cause of foodborne infections, hospitalizations, and deaths in many countries. This research demonstrates the role of surface waters as a vehicle for the transmission of Salmonella along food production chains. It also shows that some strains circulating in surface waters are very similar to those implicated in human infections and harbor genes that confer resistance to multiple antibiotics, posing a risk to public health. This study contributes to expand our current knowledge on the ecology and epidemiology of Salmonella in surface waters.

Livestock hauliers' attitudes, knowledge and current practices towards animal welfare, occupational wellbeing and transport risk factors: A Mexican survey.

Mexico is the 7th largest producer of beef in the world. The livestock transport is a vital component of today's world agrifood economy that directly impacts on the development of animal production, animal welfare, public policies, labor regulations, food safety, markets and consumers. In this study two aims were established; the first aim was to identify the attitudes and perceptions of commercial hauliers towards animal welfare and their influence on the accident risks. The second aim was to characterize the current practices of the commercial cattle transport in Mexico and to detect the risk factors for animal welfare and hauliers' wellbeing. The interviews were conducted individually at the hauliers' rest points, sanitary inspection points localized along the Federal Highway 57 or at the companies' offices of cattle transportation. We used univariate, bivariate and multivariate statistics based on a hierarchical cluster analysis. The results showed that cattle transport in Mexico is characterized for long travel distances because the cattle departed from farms in the southern states of Mexico to the feedlots located in central and northern regions of the country. The journeys of short and middle distances departed from the feedlots to the slaughterhouses. The hauliers' characteristics were: age from 29 to 48 years-old, elementary or secondary studies completed, 65% of hauliers mentioned six years of experience in cattle transport, they learned about cattle transportation by means of a family member who was already engaged in this activity. The cluster analysis identified four hauliers' groups: groups 1 and 3 were related to animal welfare and groups 2 and 4 less related to animal welfare. This study showed that empathy towards cattle was a key element in identifying hauliers at risk of road accidents during cattle transportation. Years of experience in cattle transport played an important role in emphasizing closer perceptions towards welfare. Considering current trends towards increased transport times and logistics stops, there is a need to develop systems of welfare assessment and decision-making that provide tools and protocols that can minimize the biological cost to animals and hauliers, which may have been underestimated in the past.

Mexican consumers at the point of meat purchase. Pork choice.

Use of within-consumer preference replication and systematic image manipulation in surveying showed that consumers in four cities across Mexico had similar strategies for pork choice. New surveying tools also determined preferred levels of the characteristics used in the decision-making process. The most important choice criteria were colour (31% chose dark and 21% light red), and fat cover (42% chose lean and 8% fatty). Marbling and drip were less used, but are nevertheless important given that 21% of consumers used three or four characteristics to make their choice. Split colour and marbling preferences and a range of acceptable limits for both, and a preference for the leanest fat cover available were observed. Preferences within the normal range of pork colour, fat cover achieved through trimming and drip countered by an absorbent pad all favour industry practice. Unfortunately, preferences for minimal or no marbling and fat cover likely result in a compromised gustative experience for many Mexican consumers.

Mexican consumers at the point of meat purchase. Beef choice.

Within-consumer preference replication achieved through systematic image manipulation was used in consumer surveys in four cities across Mexico (Mexico City, n=195; Guadalajara, n=100; Hermosillo, n=132; Veracruz, n=61) to study beef preferences. Images of beef steaks controlled for lean and fat colour, fat cover and marbling were presented to consumers to determine the characteristics used in beef choice and the levels of preference of these characteristics. The most important choice criteria were fat cover (62% preferring little fat cover) and marbling (59% preferring non-marbled). Lean colour was also important with 24% and 29% choosing light and dark red beef, respectively. Fat colour was the least important of the four attributes studied (18% and 19% choosing white and yellow, respectively), but was nevertheless important given that 43% of consumers used three or four characteristics to make their choice. Imported and domestic beef in the Mexican marketplace appear to respond to the range of consumers' beef preferences at the point of purchase.

Quality traits of pork semimembranosus and triceps brachii muscles sourced from the United States and Mexico.

The study included fresh pork semimembranosus (SM, n=289) and triceps brachii (TB, n=283) muscles sourced from meat packers of Mexico and the USA. Samples were analyzed for moisture, protein, and fat content, pH, shear force (WBSF), cook loss, water holding capacity (WHC), instrumental color, emulsion capacity (EC) and stability (ES), and consumer sensory ratings. SM from the USA had lower WBSF (P<0.05) than that from Mexico (26.7 vs. 29.7N), higher WHC (44.7 vs. 38.4%; P<0.05) and a better appearance, as indicated by its lower h* (52.3 vs. 56.6; P<0.05) and higher C* (23.1 vs. 21.3; P<0.05). Consumer acceptance of SM was similar (P>0.05) across countries. TB from Mexico had higher (P<0.05) fat content (2.5 vs. 2.0%), lower (P<0.05) WBSF values (32.0 vs. 36.9N), and received more positive ratings by Mexican consumers (87.1 vs. 81.7%) than its US equivalent. In general, US pork exhibits better technological properties, while country of origin has less effect on consumer acceptability.

Improving appearance and microbiologic quality of broiler carcasses with an allostatic modulator.

An important priority of poultry producers is to guarantee animal welfare during animal production; however, broilers are exposed to unavoidable chronic stress (also known as allostasis) when they are captured, caged, and transported to the processing plant. This antemortem management causes allostatic load, animal injuries, and poor carcass quality. The aim of the present study was to evaluate the effects of an allostatic modulator (AM) on antemortem stress by measuring the appearance and microbiological quality of broiler carcasses. The AM consisted of a liquid formula containing ascorbic acid, acetyl salicylic acid, and electrolytes, administered orally 48 h before shipment to the processing plant. A total of 600 chickens (49-days-old) were used under a factorial arrangement 2 × 2 × 2 [2 commercial hybrid lines, 2 feed withdrawal programs (10 and 16 h), and 2 water treatments (control and AM)]. Each treatment included 25 chickens per pen and was carried out in triplicate. The broilers were shipped, slaughtered, and processed in a commercial processing plant where carcass defects (bruises and broken bones caused by antemortem management), crop pH, and carcass bacterial counts were evaluated in all experimental groups. Broilers under AM treatment showed a reduction in carcass defects (P = 0.015), crop pH (P = 0.0001), coliforms counts (P = 0.014), and total aerobic mesophilic bacteria (P = 0.0001) when compared to the control treatment. The present study indicates that the AM can be used to improve carcass quality in broilers. Our study provides a novel and economic alternative to reduce the allostatic load in broilers.

Effect of an allostatic modulator on stress blood indicators and meat quality of commercial young bulls in Mexico.

To assess the effect of an allostatic modulator (AM) on stress blood indicators and meat quality traits, the feed of 80 non-castrated 18-20 month-old bulls was supplemented with 10 g/day of an AM for 30 days before slaughter. Another 80 bulls served as control animals. The AM was comprised of ascorbic acid, acetoxybenzoic acid and sodium and potassium chloride. Blood samples were taken at slaughter for analyses of hematocrit value, erythrocyte and leukocyte counts, and glucose, lactate and cortisol concentrations. Post-mortem measures of meat color and pH were made at 24h and color, shear force and cooking loss on meat from 20 animals at 28 days. The AM supplementation resulted in lower hematocrit value, erythrocyte count and glucose level (P<0.05), higher a* (P<0.0001) and b* (P<0.0001) at 24h and lower b* (P<0.05) at 28 days. Thus AM treatment improved some stress blood indicators and meat color and therefore merits further investigation.