Abstract Introduction: Current diets of broiler chickens tend to increase protein levels to obtain high productive variables that are achieved in combination with genetic, management, and sanitary improvements, among others. An increase in dietary crude protein levels does not always accompany an increase in broiler productive efficiency due to multiple factors involved in the production system. The objective of this study was to evaluate the effect of increasing levels of dietary crude protein (CP) on productive performance, carcass characteristics, and chemical composition of breast and thigh meat in broiler chickens raised in the dry subtropics of northeastern Mexico. Method: The study used 200, 1-day-old male Ross broiler chicks. In a completely randomized design, birds were allocated to the four treatments with five replicates (floor pens) of ten birds each. The trial was divided in two phases (starter and finisher) of 21 days each (42 days total). Treatment diets (T) for starter and finisher phases had crude protein concentrations (CP; %) of 21 and 18.1 (T1), 21.4 and 18.5 (T2), 21.8 and 18.9 (T3), and 22.2 and 19.3 (T4), respectively. Within each feeding phase, the four treatment diets were formulated to similar levels of apparent metabolizable energy. Results Protein concentrations had no effect (P > 0.05) on weight gain, while feed intake was greater in T1 (P < 0.05) than in T2 and T3. Feed conversion was better in T2 and T4 (P < 0.05) than in T1. There was no influence of treatment on carcass weight or carcass cuts (P > 0.05). Carcass yield was greater in T1 than in T3 (P < 0.05). Breast and thigh dry matter and ether extracts were similar (P > 0.05) between treatments. Breast crude protein was greater (P < 0.05) in T2 than in T3. The lowest (P < 0.05) CP concentration in thigh meat was in T3. Discussion or Conclusion: These results indicated that in the dry subtropics area of northeastern Mexico increases in CP above the level of T2 (21.4% and 18.5% CP in starter and finisher diets, respectively) did not improve broiler chicken productive performance, carcass characteristics or meat chemical composition.

Resumen Introducción: Las dietas actuales de pollos de engorda, tienden a incrementar los niveles de proteína para obtener variables productivas altas que son logradas en forma conjunta con mejoras genéticas, de manejo, sanitarias, entre otras. Sin embargo, el incremento en los niveles de proteína en la dieta no siempre acompaña el incremento en eficiencia productiva de los pollos de engorda debido a múltiples factores que intervienen en el sistema de producción. El objetivo de esta investigación fue evaluar el efecto de niveles crecientes de proteína cruda (PC) en las dietas sobre el comportamiento productivo, las características de la canal y la composición química de la carne de pechuga y muslo de pollos de engorde en el trópico seco. Método: El estudio incluyó 200 pollos de engorde Ross de 1 día de edad. Las dietas de tratamientos (T) para las fases de inicio y finalizado tuvieron concentración de proteína cruda (PC; %) de: 21 y 18.1 (T1); 21.4 y 18.5 (T2); 21.8 y 18.9 (T3); 22.2 y 19.3 (T4), respectivamente. Dentro de cada una de las fases de alimentación, las cuatro dietas de tratamiento fueron formuladas con niveles similares de energía metabolizable aparente. En un diseño completamente aleatorio, las aves fueron asignadas a los cuatro tratamientos con cinco réplicas (corrales de piso) de 10 aves cada una. El ensayo se dividió en dos fases (inicio y finalizado) de 21 días cada una (42 días en total). Resultados: La concentración de proteínas no tuvo ningún efecto (P > 0.05) en el aumento de peso, mientras que el consumo de alimento fue mayor en T1 (P < 0.05) que en T2 y T3. La conversión alimenticia fue mejor en T2 y T4 (P < 0.05) que en T1. No hubo influencia del tratamiento en el peso o en los cortes de la canal (P > 0.05). El rendimiento de la canal fue mayor (P < 0.05) en T1 que en T3. La materia seca y el extracto etéreo de la carne de la pechuga y el muslo fueron similares (P > 0.05) entre los tratamientos. La proteína cruda de la pechuga fue mayor (P < 0.05) en T2 que en T3. La menor (P < 0.05) concentración de PC en la carne de muslo fue en T3. Discusión o Conclusión: Estos resultados indican que en la zona subtropical del noreste de México los aumentos de PC sobre los valores de T2 (21.4% y 18.5% PC en dietas de inicio y finalizado, respectivamente) no mejoraron el rendimiento productivo, las características de la canal o la composición química de la carne de pollos de engorde.

Abstract: The objective of this study was to evaluate the effect of agave inulin (AI) and Mexican oregano essential oil (MOEO) on the productive behavior, slaughter variables and quality of broiler meat. A total of 330, 1-day-old Ross-308 broilers were randomly assigned to six treatments with five replications each (11 chickens per pen): T1 = control diet, T2 = diet + 5.0 g kg-1 AI, T3 = diet + 10.0 g kg-1 AI, T4 = diet + 5.0 g kg-1 AI + 0.2 g kg-1 MOEO, T5 = diet + 10.0 g kg-1 AI + 0.2 g kg-1 MOEO, and T6 = diet + 0.2 g kg-1 MOEO. Chickens in T4 and T5 (p < 0.05) weighed less than in T1, but feed consumption was higher in T2 (5.63 kg) and the lowest in T6 (4.77 kg). Sacrifice and wing weight (p < 0.05) were higher in T1 and lower in T5 and T4. Water retention, hardness and gomosity (p < 0.05) were higher in T3 (63.2%; 9.36 kgf; 3204.9 g) and lower in T1 (56.98%; 7.28 kgf; 2532.7 g), and the yellow color was higher in T5 and lower in T3. Agave inulin (10.0 g kg-1) and oregano oil (0.2 g kg-1) can be used in broilers to improve meat production and quality.

Resumen: El objetivo del estudio fue evaluar el efecto de la inulina de agave (IA) y aceite esencial de orégano Mexicano (AEOM) en el comportamiento productivo, variables de sacrificio y calidad de la carne de pollos de engorda. Un total de 330 pollos de engorda (1 día de edad) Ross-308 se asignaron de forma aleatoria a seis tratamientos con cinco repeticiones cada uno (11 pollos por corral): T1 = dieta control, T2 = dieta + 5.0 g kg-1 IA, T3 = dieta + 10.0 g kg-1 IA, T4 = dieta + 5.0 g kg-1 IA + 0.2 g kg-1 AEOM, T5 = dieta + 10.0 g kg-1 IA + 0.2 g kg-1 AEOM, y T6 = dieta + 0.2 g kg-1 AEOM. Los pollos de T4 y T6 (p < 0.05) pesaron menos que T1, pero el consumo de alimento fue más alto en T2 (5.63 kg) y el más bajo en T6 (4.77 kg). El peso sacrificio y alas (p < 0.05) fueron más altos en T1 y más bajos en T5 y T4. La retención de agua, dureza y gomosidad (p < 0.05) fueron mayores en T3 (63.2%; 9.36 kgf; 3204.9 g) y menores en T1 (56.98%; 7.28 kgf; 2532.7 g), y el color amarillo fue más alto en T5 y más bajo en T3. La inulina de agave (10.0 g kg-1) y el aceite de orégano (0.2 g kg-1) pueden usarse en la engorda de pollos para mejorar la producción y calidad de la carne.

Abstract: An electrochemical prototype (ECP) was developmed and evaluated to determine NaCl electrical variables [volt (V), ampere (A), resistance (R) and power (P)] and its use in fresh cheeses. The ECP circuit consisted of two electrodes, an aluminum (anode) and a copper (cathode). The experimental parameters established in the ECP were distance between electrodes and the presence of a resistor. Seven treatment solutions were examined at 0, 2, 4, 6, 8, 10 and 12 g of NaCl/100 mL of water. Cheeses evaluated were a commercial cheese (Control) and a commercial light cheese. Treatment influenced (P<0.05) the electrical variables in NaCl solutions and cheeses. Regression analysis showed that the best fit was a quadratic model for the ECP. Prototype results showed that at higher NaCl concentrations, voltage and resistance decreased, while amperage and power increased.

Resumen: Se desarrolló y evaluó un prototipo electroquímico (PEQ) para la medición de variables eléctricas [voltios (V), amperaje (A), resistencia (R) y potencia (P)] en soluciones que contienen NaCl y se probó en quesos frescos. El circuito del PEQ consistió en dos electrodos (un ánodo de aluminio y un cátodo de cobre), un multímetro y una resistencia. Los parámetros experimentales establecidos en el PEQ fueron la distancia entre electrodos (0.5 o 4.0 cm) y la presencia de la resistencia. Se evaluaron siete tratamientos (soluciones) con diferentes concentraciones de NaCl: 0, 2, 4, 6, 8, 10 y 12 g de NaCl/100 ml de agua. Los quesos evaluados fueron un queso comercial (control) y otro “light” (bajo en calcio, sodio y grasa). Las variables eléctricas difirieron (P<0.05) entre los tratamientos y entre los quesos. Un análisis de regresión mostró que un modelo cuadrático dio el mejor ajuste para el PEQ. Los resultados indicaron que a mayores concentraciones de NaCl el voltaje y la resistencia disminuyeron mientras que el amperaje y la potencia aumentaron. El prototipo electroquímico detectó estos cambios de manera rápida y eficaz tanto en soluciones salinas como en quesos frescos, demostrando que es una técnica válida para el análisis de la composición de productos lácteos.

ABSTRACT The current study was conducted to investigate the effects of Mexican oregano essential oil (MOO) extracts from Lippia berlandieri Schauer (LBS) and Poliomintha longiflora Gray (PLG) on performance, blood profiles, carcass variables, and meat composition of broilers at slaugther. A total of 360 one-day-old Ross broilers were randomly distributed into four dietary treatments with six replicate pens per treatment and 15 birds per pen. The dietary treatments were: a basal diet (control), control + 0.40 g of LBS/kg of feed, control + 0.40 g of PLG/kg, and control + 0.40 g of LBS/kg + 0.40 g of PLG/kg. Results showed that linear, quadratic, and cubic effects of days were significant in the performance variables of broilers. The treatments with LBS and PLG maintained the broiler body weight without increasing feed intake and water intake when compared with the control group. Broilers given LBS+PLG and PLG had increased blood leukocytes, lymphocytes, low-density lipoprotein, and hot carcass yields. In meat composition, treatments with PLG and LBS+PLG presented similar breast protein content compared with the control treatment. Supplementation with these two MOO exhibits positive effects on broiler performance, blood profiles, carcass traits, and meat composition. These two MOO may be promising feed supplements as growth promoters and enhancers of meat quality in broiler production.

ABSTRACT The objective of the current study was to evaluate performance, blood parameters, and carcass yield of broilers supplemented with Mexican oregano oil. A total of 162 one-day-old broilers were randomly distributed into three dietary treatments: control diet (without oregano oil or antibiotic); control diet + 0.25 g kg−1 of oxytetracycline; and control diet + 0.4 g kg−1 of Mexican oregano oil. Treatment with organ oil had positive effects on body weight at 35 and 42 days. Feed intake was significantly different at 21 and at 1-42 days; control treatment presented the highest feed intake at 28 and 35 days, while treatment with oxytetracycline had the lowest feed intake from 21 to 42 days. Weekly body weight gain was different at 42 days, in which treatment with oregano oil was the highest and control the lowest. Feed efficiency rate was significantly different at 42 and at 1-42 days; treatment with oxytetracycline and treatment with oregano oil had the best values over control treatment. Blood parameters were found different among treatments, in which treatment with oregano oil was the highest in cholesterol and high-density lipoprotein at 42 days. Carcass and blood biometric variables were not different among treatments. The amount of 0.4 g kg−1 of Mexican oregano oil in diets improves high-density lipoprotein, body weight, and feed efficiency rate of broiler chickens.

ABSTRACT: The quality of slaughtered turkeys fed a diet supplemented with Mexican orégano (Lippia berlandieri Schauer) oil was investigated. Two treatments were studied. T0: control diet and TI: control diet + 400 mg kg-1 of orégano oil with 60 % carvacrol. Live weight at slaughter was different, with T0 weighing 11.0 kg and TI 11.89 kg, while the performance of feathers and drumstick was higher in T0 (4.33 and 3.18 % respectively). Viscera, blood, head, neck and hot and coid carcass yield did not differ between treatments (p > 0.05). Orégano oil at 400 mg kg-1 can be used in the production of turkeys to influence slaughter quality.

RESUMEN: La inclusión de aceite de orégano mexicano (Lippia berlandieri Schauer) en dietas de pavos fue inves tigada sobre la calidad en el sacrificio de los pavos. Se evaluaron los tratamientos T0: dieta testigo y TI: dieta testigo + 400 mg kg-1 de aceite de orégano con 60 % de carvacrol. El peso vivo al sacrificio de los pavos fue diferente, T0 presentó 11.0 kg y TI 11.89 kg, mientras que el rendimiento de plumas y patas fue mayor en T0 (4.33%) que TI (3.18 %). En tanto que en visceras, sangre, cabeza, cuello, rendimiento de canal caliente y fría no se detectaron diferencias entre tratamientos. El aceite de orégano en 400 mg kg-1 puede ser usado en la producción de pavos para influir sobre la calidad en el sacrificio.

The objective of this research was to evaluate the inclusion of two qualities of Mexican oregano oil (MOO) in broiler diets on broiler weight, feed intake, feed efficiency, average daily gain, and water intake. The qualities were MOO1 (4% thymol, 60% carvacrol) and MOO2 (40% thymol, 20% carvacrol). Nine treatments were prepared by the combinations of MOO1 + MOO2 (0, 400, and 800 mg kg−1; added per kg of feed) respectively: 0+0, 0+400, 0+800, 400+0, 400+400, 400+800, 800+0, 800+400, and 800+800. Eighteen chicks per treatment were divided in a completely randomized design into nine cages. Broiler weights were altered by the treatments at 21 d, when 400+400 had the highest weight, and on day 39, when the greatest weight was seen in broilers on treatments 800+0 and 800+400. Feed intake was affected by treatment on day 39, with broilers on 800+0 exhibiting the highest values. Water intake was influenced by the treatments on days 14, 21, 35, and 39, when 0+0 represented the lowest. Feed efficiency was altered by the treatments on days 14, 28, 35, and 39, whereas average daily gain was affected from days 14 to 39. Supplementation of Mexican oregano oil has beneficial effects on broiler weight, feed efficiency, average daily gain, and feed and water intakes. Combinations of thymol and carvacrol levels have varying effects on these parameters. The higher relative body weights of groups 400+0, 800+0, and 800+400 suggest positive market value effects of these combinations of Mexican oregano oil.