Abstract In Mexico, avocado and guava production generate agronomic residues that contain bioactive compounds as secondary metabolites produced in plants. Their consumption offer favourable health effects; therefore, the objective of the present research was to characterize the bioactive compounds and antioxidant properties in guava (Psidium guajava L.) and avocado (Persea americana Mill.) residues (pulp or epicarp and leaves) at different ethanol concentrations (T1 100%, T2 75%, T3 50% and T4 25%, v/v) and in aqueous extracts (T5). Avocado epicarp (56.17 mg of EAG g-1 dm) and guava leaves 50% extracts (45.13 mg of EAG g-1 dm) presented the highest total phenol content; consequently, as it was expected avocado epicarp (328.95 TEAC/g dm) and guava leaves 25% extracts (320.01 TEAC/g dm) shown the highest antioxidant capacity. On the other hand, the highest saponins values were at avocado (100.60 mg g-1 dm) and guava leaves (76.96 mg g-1 dm) 25% extracts. Then avocado epicarp and guava leaves extracts are suggested as a high potential for agro-industrial, pharmacological and chemical uses.

Abstract Garlic (Allium sativum), as a natural antimicrobial, has favored animal welfare, as well as the safety and quality of the meat. The objective of this study was to assess the production indicators and the physical and microbiological quality of the meat of rabbits fattened with the addition of aqueous extract of garlic (AEG) to their diet. A completely randomized design was carried out with three treatments of 28 New Zealand rabbits X Chinchilla (Oryctolagus cuniculus X Chinchilla chinchilla) each (LW 1 ± 0.6 kg, 30 ± 5 d); control group (food only), treatment 1 (0.9% AEG) and treatment 2 (1.8% AEG, sprinkled on the food every 3 d). Daily weight gain and food conversion were determined to occur during four weeks after weaning. Aerobic mesophiles, fecal coliforms, and psychrophiles were quantified in the meat, and the pH and color (B*, a* and b*) were determined, all in Longissimus dorsi, at 1, 3, 5, 7 and 9 d of storage in refrigeration. A multivariate variance analysis (P≤0.05) and a Tukey test at 5 % were performed for the production indicators and the physical and microbiological variables. Unlike in psychrophiles and mesophiles, there were no significant differences (P≥0.05) in the production indicators throughout the time of conservation. No fecal coliforms were observed in any of the samples. The addition 1.8% of aqueous extract of garlic improved the shelf life by two days (total: 9 d) by reducing the content of psyschrophiles, without affecting the production indicators or the physical quality of the meat.

Resumen El ajo (Allium sativum) como antimicrobiano natural ha favorecido el bienestar animal, inocuidad y calidad de la carne. El objetivo de este estudio fue evaluar indicadores productivos, calidad física y microbiológica de la carne de conejos, engordados con la adición de extracto acuoso de ajo (EAA) en la dieta. Se realizó un diseño completamente aleatorio con tres tratamientos de 28 conejos Nueva Zelanda X Chinchilla (Oryctolagus cuniculus X Chinchilla chinchilla) cada uno (PV 1 ± 0,6 kg, 30 ± 5 días); grupo testigo (solo alimento), tratamiento 1 (0.9% EAA) y tratamiento 2 (1.8% EAA) asperjado en el alimento cada tres días. Se determinó, ganancia de peso diaria y conversión alimenticia, durante cuatro semanas a partir del destete. Se cuantificó en la carne mesófilos aerobios, coliformes fecales, psicrófilos, y se determinó pH y color (L*, a* y b*), todo ello en Longissimus dorsi a los 1, 3, 5, 7 y 9 días de conservación en condiciones de refrigeración. Se realizó un análisis de varianza multivariado (P≤0,05) para los indicadores productivos, variables físicas y microbiológicas, más una prueba de Tukey 5%. No existieron diferencias significativas (P≥0,05) sobre los indicadores productivos y sí para psicrófilos y mesófilos aerobios, a lo largo del tiempo de conservación. No se observaron coliformes fecales en ninguna de las muestras. La adición de extracto acuoso de ajo 1.8% mejoró la vida útil al disminuir el contenido de piscrófilos y aumentar dos días la vida de anaquel (total 9 días), sin afectarse indicadores productivos, ni la calidad física de la carne.

The aim of this study was to evaluate the effect of the complete yeast supplement (LC) and the cell wall (PcSc) of Saccharomyces cerevisiae on the weight gain, feed conversion and characteristics of the carcass in Rambouillet lamb. The treatments were: T1 (without LC and without PcSc), T2 (1 g/kg-1 MS LC) and T3 (0.6 g/kg-1 MS PcSc) with six repetitions (lambs) per treatment. The experiment lasted 55 days. Eighteen lambs (36.5 ± 2.5 kg) were housed in individual pens and received water and a diet that provided 14.8% protein and 12 384.64 kJ/kg-1 MS. Daily weight gain and feed conversion were evaluated during fattening, as well as the weight of the hot and cold carcass, pH, temperature (45 min and 24 h) and target color (24 h) of the carcass. There were no significant differences for daily body-weight gain or for feed conversion due to the treatments, but in the color characteristics the variables a* and C had a significant difference (p<0.05) when adding LC or PcSc.

El objetivo del estudio fue evaluar el efecto del suplemento de levadura completo (LC) y de la pared celular (PcSc) de Saccharomyces cerevisiae sobre la ganancia de peso, conversión alimenticia y características de la canal del cordero Rambouillet. Los tratamientos fueron: T1 (sin LC y sin PcSc), T2 (1 g/kg-1 MS LC) y T3 (0.6 g/kg-1 MS PcSc) con seis repeticiones (corderos) por tratamiento. La prueba duró 55 días. Se trabajó con 18 corderos (36.5±2.5 kg) alojados en corrales individuales que recibieron agua y una dieta que proporcionó 14.8% de proteína y 12 384.64 kJ/kg-1 MS. Se evaluó la ganancia diaria de peso y la conversión alimenticia durante la engorda, así como el peso de la canal caliente y fría, pH, temperatura (45 min y 24 h) y el color objetivo (24 h) de la canal. No hubo diferencias significativas para la variable ganancia diaria de peso ni para conversión alimenticia por efecto de los tratamientos, pero las variables de color a* y C tuvieron una diferencia estadística significativa (p<0.05) al agregar LC o PcSc.

Pork chemical and sensory characteristics of 48 barrows were used to evaluate the effect of ractopamine (5 PPM, Paylean, Elanco México) in diets formulated to three standardized ileal digestible-lysine (SID-Lys) levels. All diets had 3.3 Mcal EM/kg, and 14.5 % crude protein (CP), this represent a 10 % lower CP content than that recommended by the laboratory and the literature. Pigs (initial BW 77.2±3.42 and final BW 110.0±3.0 kg) were randomly alloted to one of four treatments: C) Control diet, 0.65 % SID-Lys; RHL) ractopamine, high lysine level, 1 % SID-Lys; RNL) ractopamine, normal lysine level, 0.8 % SID-Lys; RLL) ractopamine, low lysine level, 05 % SID-Lys. After 28 d of ad libitum intake, pigs were killed; from each pig, four 2.5 cm thick chops were used for chemical and sensory analyses. Adding RAC in diets with 14.5 % CP increases (P<0.01) intramuscular fat in 25 %. A higher increase (until 50 %) was achieved when RAC was used in a diet with a low SID-Lys. Pork chop consumer acceptance was evaluated using a panel that consisted of 60 consumers. They were not able to detect differences in texture, flavor and aroma (P>0.17), but they detected a higher juiciness (P<0.02) in chops from pigs fed the RLL diet. By improving marbling and juiciness, RAC-containing diets supplemented with low levels of crude protein and low SID-Lys can improve pork quality.

Se evaluaron las características químicas y sensoriales de la carne de cerdos alimentados con Ractopamina (RAC) a 5 ppm (Paylean®, Elanco, México) y diferentes concentraciones de lisina digestible ileal estandarizada (lys-dig), en dietas con 3.3 Mcal EM/ kg y 14.5 % de proteína cruda, lo que representa un contenido de proteína de 10 % inferior al mínimo recomendado por el laboratorio y la literatura. Se utilizaron 48 cerdos (peso corporal inicial 77.2±3.42 y final 110.0±3.0 kg) que fueron asignados a uno de cuatro tratamientos: C) Dieta de finalización Control (lys-dig 0.65%); RAL) alta en Lisina con RAC (lys-dig 1%); RNL) Niveles normales de lisina con RAC (lis-dig 0.80%); RBL) Baja en lisina con RAC (lis-dig 0.50%). Después de 28 días en sus respectivas dietas, los animales se sacrificaron y procesaron. De cada animal, se recolectaron cuatro chuletas (2.5 cm de grosor) y se determinó grasa intramuscular y evaluación sensorial. Los resultados indican que con la adición de RAC, en dietas con 14.5 % de proteína, se aumenta (P<0.01) la grasa intramuscular en 25 %. Un incremento mayor (hasta el 50 %) en grasa intramuscular se obtuvo con dietas con RAC y una baja concentración de lisina (0.5% lys-dig). El panel de consumidores no detectó diferencias en aroma, sabor y textura (P>0.17), pero sí detectó una mayor jugosidad de carne de cerdo (P<0.02) de animales que consumieron la dieta RBL. Es factible mejorar la calidad de la carne de cerdo mediante el uso de RAC y dietas bajas en proteína y lisina.