Abstract Vegetable dietary protein sources are cheaper alternatives to fishmeal in shrimp diets. This study assessed the impact of fermented and non-fermented soybean and canola meals on growth performance, in vivo and in vitro digestibility, digestive enzyme activities and meat quality of Litopenaeus van-namei. A total of 513 shrimps were randomly assigned to treatments (control and two experimental diets). Animals on the control diet (CD) were fed a commercial feed concentrate. For the other treatments, the fishmeal protein source was totally replaced by a mixture of soybean and canola meal (50:50), either unfermented (SC) or fermented (FSC). Results showed that fermentation significantly increased (P < 0.05) the hydrolysis degree (HD) of SC meals by 12 % compared to that of their unfermented counterparts. Also, it was found that canola meal had higher HD compared to soybean meal, both before and after fermentation. The use of SC diet decreased protein digestibility in shrimps (P < 0.05), although there was no significant variation in the activity of total proteases and chymotrypsin. Production performance traits of shrimps fed diets with FSC were comparable to those of shrimps on the control diet. The increase in shear force of shrimps fed FSC was accompanied by an increase in the water holding capacity (WHC) by 8-9 % (P < 0.05). Sensory attributes were similar across diets. In summary, this study showed it is possible to fully replace fish meal with FSC in shrimp diets without impairing production performance traits, dietary protein digestibility, and shrimp meat quality.

Abstract: An allostatic modulator (AM) composed of ascorbic acid, acetylsalicylic acid, sodium chloride and potassium chloride was dissolved in the drinking water of three groups of young bulls (n = 7) and administered to them for 7 d after 20.42 h of transport (Control (C) = 0 g/head/d, G2 = 30 g/head/d, G3 = 60 g/head/d). The effects of the AM on behavior and blood cellular and biochemical components were measured. G3 animals spent less time lying and more time standing than C animals (P = 0.001 and P = 0.02, respectively), indicating less fatigue. G3 bulls presented a lower frequency of agonistic interactions than those in the G2 group (P = 0.001), suggesting a possible effect on aggression that warrants further evaluation. The AM affected creatinine kinase (CK) activity in the G2 group compared to the C group (P = 0.04), suggesting an effect of AM components that has not been previously reported. Cortisol levels remained unaffected by AM supplementation (P = 0.55). These preliminary findings suggest an effect of supplementing cattle with an AM after long-haul transport.

Beef can be contaminated during the slaughter process, thus other methods, besides the traditional water washing, must be adopted to preserve meat safety. The objective of this study was to evaluate the effect of 2% acetic acid interventions on the reduction of indicator bacteria on beef carcasses at a commercial slaughterhouse in Mexico. Reduction was measured by the count of mesophilic aerobic bacteria (TPC), total coliform (TC), and fecal coliform (FC) (log CFU/ cm²). Among the different interventions tested, treatments combining acetic acid solution sprayed following carcass water washing had greater microbial reduction level. Acetic acid solution sprayed at low pressure and longer time (10-30 psi/ 60 s) reached higher TPC, TC, and FC reductions than that obtained under high pressure/ shorter time (1,700 psi/ 15 s; P<0.05). Exposure time significantly affected microbial reduction on carcasses. Acetic acid solution sprayed after carcass washing can be successfully used to control sources of indicator bacteria on beef carcasses under commercial conditions.

The effect of different natural antimicrobial agents (nisin - 3%, sodium lactate - 3%, potassium lactate - 3%, acetate-lactate - 1%) on beef patty shelf-life, aspect and consumer acceptance was evaluated. In the first experiment, patties were inoculated with E. coli and stored for 8 d at 4 °C. In the second experiment, patties were not inoculated with E. coli and stored for 10 d at 4 °C. During storage, patties were evaluated for microbial growth, pH, color and sensory properties (second experiment only). Addition of nisin provided the highest inhibition of microbial growth and maintained proper pH levels. Addition of the lactates and acetate-lactate also significantly inhibited microbial growth compared to the control and did not affect meat color. Despite its antimicrobial effect, addition of nisin negatively affected sensory acceptance of beef patties compared to the other treatments.

Se evaluó el efecto de la utilización de diferentes antimicrobianos naturales (nisina - 3%; lactato de sodio - 3%; lactato de potasio - 3%; acetato-lactato - 1%) sobre la estabilidad de hamburguesas de carne de res. En la primera etapa del estudio, las hamburguesas fueron inoculadas con E. coli y mantenidas en refrigeración por ocho días. En la segunda etapa, las hamburguesas, sin la inoculación de E. coli, fueron refrigeradas por 10 días. Las muestras se evaluaron para color, pH, conteo microbiológico y atributos sensoriales (hamburguesas de la segunda etapa). La adición de nisina promovió la mayor inhibición microbiana y la mejor estabilidad del pH de las hamburguesas. La adición de lactatos y acetato-lactato mostró significativo efecto de inhibición del crecimiento microbiano, sin presentar efecto sobre el color de la carne. No obstante de su efecto antimicrobiano, la adición de nisina afectó negativamente la aceptación sensorial de las hamburguesas.

The objective of this project was to detect the presence of Listeria monocytogenes, Salmonella and Yersinia enterocolitica in Mexican and imported beef steaks purchased at supermarkets in three cities of Mexico. Prior to testing beef products, detection limits using PCR-based methods were conducted from both pure bacterial cultures as well as inoculated beef. A total of 90 samples, half of Mexican and half of imported origin, were collected in this study. Overall, a total of 27.78 % of samples tested via PCR were positive for L. monocytogenes, 8.89 % for Salmonella and 28.89 % for Y. enterocolitica, respectively. None of the imported samples tested positive for Salmonella. Mexican samples had a higher Listeria, Yersinia, and Salmonella presence than imported samples, indicating a possible health risk to consumers purchasing this type of product. These results emphasize the need to implement the mandatory use of preventive and control programs, Sanitation Standard Operating Procedures (SSOPs) and HACCP in the Mexican meat industry.

El objetivo de este trabajo fue detectar la presencia de Listeria monocytogenes, Salmonella y Yersinia enterocolitica en carne de res, mexicana e importada, adquirida en supermercados en tres ciudades de México. Antes de analizar los productos cárnicos, se estimó el límite de detección usando métodos basados en reacción en cadena de la polimerasa (PCR), tanto de cultivos bacterianos puros como de carne inoculada. Un total de 90 muestras, mitad mexicanas y mitad importadas, fueron recolectadas en este estudio. Un total de 27.78 % muestras analizadas por PCR fueron positivas a L. monocytogenes, 8.89 % a Salmonella y 28.89 % a Y. enterocolitica. Ninguna de las muestras importadas fue positiva a Salmonella. Las muestras mexicanas presentaron mayor índice de Listeria, Yersinia y Salmonella que las muestras de carne importada, lo que indica un posible riesgo de salud para los consumidores que adquieren este tipo de producto. Estos resultados enfatizan la necesidad de implementar de forma obligatoria programas de prevención y control, Procedimientos Operativos Estandarizados de Sanitización (POE's- SSOP's en inglés) y Análisis de Peligros y Puntos de Control Críticos (APPCC- HACCP en inglés) en la industria cárnica mexicana.