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Abstract Background: The use of early nutrient-restriction programs in broilers can prevent complications such as increased body fat deposition and its consequences. However, feed restriction not always gives the expected results. Objective: To assess the effect of two levels of feed restriction followed by a re-alimentation period with five increasing nutrient levels on growth performance and immune response of broiler chickens. Methods: A total of 330 animals were used. The treatments were: 25 (T25) and 35% (T35) quantitative feed restriction during the starting period, and 0, 2.5, 5, 7.5, 10, and 15% increased energy and protein contents during the growing and finishing periods. Results: For all the T25 treatments, except for T25-0, feed intake (FI) and body weight gain (BWG) were higher, and feed conversion rate (FCR) was lower (p<0.05) compared to the control treatment. In that group, the response of FI and BWG to the increased nutrient density was mostly quadratic (p<0.001), whereas that of FCR was linear (p<0.001). The FI and BWG results were less homogeneous in the T35 treatments, but FCR was lower compared to the control treatment (p<0.05) in all of them. The FCR showed no differences (p>0.05) between treatments during the finishing period. Conclusion: Feeding a nutrient-dense diet after a period of mild feed restriction gives the best results, while increasing nutrient density after a more severe feed restriction does not improve productive results compared to a standard diet. Carcass traits and immune function were not affected by restriction level or nutrient density.

Resumen Antecedentes: El uso de programas de restricción alimenticia temprana en pollos de engorde puede prevenir el incremento de la deposición de grasa corporal y sus consecuencias. Sin embargo, la restricción alimenticia no proporciona siempre los resultados esperados. Objetivo: Investigar los efectos de dos niveles de restricción alimenticia seguida por un período de realimentación con cinco niveles crecientes de nutrientes sobre el rendimiento productivo y la respuesta inmune de pollos de engorde. Métodos: Se utilizaron 330 animales. Los tratamientos fueron: restricción cuantitativa del 25 (T25) y del 35% (T35) durante el periodo de iniciación y aumento de la energía y contenido proteico de la dieta del 0, 2,5, 5, 7,5, 10 y 15% durante los periodos de crecimiento y finalización. Resultados: Para casi todos los T25 el consumo de alimento (FI) y el aumento de peso corporal (BWG) fueron mayores y el índice de conversión (FCR) menor (p<0,05) en comparación con el control. La respuesta del FI y el BWG al aumento de la densidad de nutrientes en este grupo fue mayoritariamente cuadrática (p<0,001), mientras que en el caso del FCR fue lineal (p<0,001). Los resultados del FI y el BWG fueron menos homogéneos en los T35, pero el FCR fue menor que en el control (p<0,05). El FCR no mostró diferencias (p>0,05) entre tratamientos durante el periodo de acabado. Conclusión: La alimentación con una dieta rica en nutrientes después una restricción ligera proporciona los mejores resultados, mientras que el incremento de la densidad de la dieta después de una restricción severa no mejora los resultados productivos en comparación con una dieta estándar. Las características de la canal y la respuesta inmune no se vieron afectadas por el nivel de restricción o la densidad de nutrientes de la dieta.

Resumo Antecedentes: O uso de programas de restrição precoce de nutrientes em frangos de corte tem o potencial de prevenir complicações como o aumento da deposição de gordura corporal e suas consequências. No entanto, a restrição alimentar nem sempre dá os resultados esperados. Objetivo: Investigar os efeitos de dois níveis de restrição alimentar seguidos de um período de re-alimentação com cinco níveis crescentes de nutrientes no rendimento produtivo e na resposta imune de frangos de corte. Métodos: Foram utilizados 330 animais. Os tratamentos foram: restrição quantitativa de 25 (T25) e 35% (T35) durante o período inicial e aumento do conteúdo energético e proteico da dieta de 0, 2,5, 5, 7,5, 10 e 15% durante os períodos de crescimento e finalização. Resultados: Para todos os tratamentos T25, menos para T25-0, consumo de ração (FI) e ganho de peso corporal (BWG) foram maiores e a taxa de conversão (FCR) foi menor (p<0,05) o controle. A resposta do FI e do BWG ao aumento da densidade de nutrientes nesse grupo foi principalmente quadrática (p<0,001), enquanto no caso da FCR foi linear (p<0,001). Os resultados do FI e do BWG foram menos homogêneos nos tratamentos T35, mas o FCR foi menor que no tratamento controle (p<0,05). O FCR não apresentou diferenças (p>0,05) entre os tratamentos durante o período de terminação. Nenhuma tendência clara foi observada no peso relativo dos órgãos linfóides ou na resposta imune devido aos tratamentos testados. Conclusão: A alimentação de uma dieta rica em nutrientes após um período de restrição leve proporcionou os melhores resultados, enquanto o aumento da densidade de nutrientes na dieta após uma restrição severa não melhorou os resultados produtivos em comparação com uma dieta padrão.

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Probiotic effects on growth performance, carcass traits, blood parameters, cecal microbiota, and immune response of broilers were studied. Two hundred one-day-old male chickens were allocated to one of five treatments (four replicates of 10 birds per treatment): control, and the same control diet supplemented with 0.005%, 0.01%, 0.015% and 0.02% probiotics. Probiotics in feed at 0.01% or higher levels of supplementation improved body weight gain (+12%) and feed conversion rate (-5%) compared with the control. There were no effects on carcass traits, but the relative weights of drumsticks and wings showed increasing and decreasing linear responses, respectively, to probiotic supplementation level. Blood plasma glucose and albumin contents linearly increased (from 167.1 to 200.5 mg dl-1, and from 1.70 to 3.25 g dl-1) with increasing probiotic supplementation. Triglycerides and cholesterol contents were lower in probiotic supplemented treatments (average contents 71.3 and 125.3 mg dl-1 vs. 92.6 and 149.9 mg dl-1 in the control). Probiotics decreased cecal Escherichia coli counts, but had no effects on immunity related organs or immune response. The linear trends, either positive or negative, observed in many of the parameters studied, suggest that more studies are needed to establish the optimal concentration of probiotics in broiler feed.

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Background: Poultry strains used by the industry have been submitted to intensive genetic selection for rapid growth and increased effi ciency of feed utilisation along with a high metabolic rate. As major consequences a loss in the immune system competency and increased sensibility to stressors are pointed out. Several nutritional strategies have been essayed to alleviate immuno-suppression in broilers, including the administration of rich 3n- polyunsaturated fatty acids. The purpose of the current study was to investigate the effects of fi sh oil and green tea feeding in broilers chicks humoral immunity using different challenges and the weight of immunity-related organs.Materials, Methods & Results: In the present study, different combinations of fi sh oil (FO) and green tea powder (GrT) supplements were tested in a 3x3 combination of supplement proportions (0%, 1.5% and 2% FO and0%, 1% and 1.5% GrT), in a total of 270 Ross 308 broilers, to analyse the effects of supplementation on the humoral immune response to challenges against Infl uenza and Newcastle virus (antibody titers) and to SRBC (immunoglobulin production) and also in the weight of liver and main lymphoid organs at slaughter. At the end of the study, the carcass weight was similar between groups and to the reported in other studies for the same age at slaughter. On respect to the responses to viral challenges...

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Objective. A 42-days feeding trial was carried out to evaluate the influences of differently thermal processed soybean meal on the broilers blood biochemical parameters. Materials and methods. A total of 200 male birds of Ross strain were allocated into five different diets formulated using differently heat-treated soybean meals, with ten birds per treatment and per replicate. Diets contained: raw soybean (controls), autoclaved for a short (121°C, 20 min; Aut1 group) or medium length period (121°C, 30 min; Aut2 group) soybean meal, micro-waved soybean meal (46°C, 540 Watt, 7 min; McW group) and browned soybean meal (120°C, 20 min; Brn group). Results. Blood serum metabolites showed that all treated diets presented lower lipid metabolism makers and higher protein metabolism markers. Broilers showed increased final body weight when fed heat-treated meals compared with control. Results suggested that thermal treatments altered the lipid metabolism in broilers that might originate a decrease in abdominal fat deposition. Conclusions. Comparison of the results for all the treated groups showed the Aut2 treatment is the most suitable method for soybean thermal treatment processing; in contrast, the Aut1 treatment had the closest results to the control group.

Objetivo. Se llevó a cabo un estudio de 42 días para determinar la influencia de la introducción de harina de soja sometida a diferentes procesos térmicos sobre los parámetros sanguíneos bioquímicos de pollos de engorde. Materiales y métodos. Un total de 200 pollos machos, de raza Ross, fueron asignados a cinco dietas equivalentes conteniendo harina de soja sometida a diferentes tratamientos térmicos, creando grupos de10 aves por cada tratamiento y por replicado. Los tratamientos térmicos fueron: harina de soja en bruto (Grupo control), harina de soja en autoclave durante un período de tiempo corto (121°C, 20 min; Grupo Aut1) o medio (121°C, 30 minutos; Grupo Aut2), harina de soja irradiado en el microondas (46°C, 540 Watts, 7 min; Grupo McW) y harina tostada de soja (120°C, 20 min; Grupo Brn). Resultados. Todos los grupos de tratamiento mostraron una disminución delos niveles de los marcadores de metabolismo de los lípidos y un aumento del metabolismo de la proteína circulante, en comparación con el grupo control. Los pollos alimentados con dietas conteniendo soja tratada mostraron además un aumento en su peso corporal final, en comparación con los del control. Los resultados sugieren que los tratamientos térmicos interfieren con el metabolismo de los lípidos, lo que puede originar una menor deposición de grasa abdominal en los pollos. Conclusiones. La comparación de los datos obtenidos para los diferentes tratamientos térmicos identifica el tratamiento en autoclave (Aut2) como el método más adecuado para el procesamiento de la soja. En contraste, el tratamiento en autoclave (Aut1) demostró ser el método con resultados más semejantes a los del control.

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Background: Poultry strains used by the industry have been submitted to intensive genetic selection for rapid growth and increased effi ciency of feed utilisation along with a high metabolic rate. As major consequences a loss in the immune system competency and increased sensibility to stressors are pointed out. Several nutritional strategies have been essayed to alleviate immuno-suppression in broilers, including the administration of rich 3n- polyunsaturated fatty acids. The purpose of the current study was to investigate the effects of fi sh oil and green tea feeding in broilers chicks humoral immunity using different challenges and the weight of immunity-related organs.Materials, Methods & Results: In the present study, different combinations of fi sh oil (FO) and green tea powder (GrT) supplements were tested in a 3x3 combination of supplement proportions (0%, 1.5% and 2% FO and0%, 1% and 1.5% GrT), in a total of 270 Ross 308 broilers, to analyse the effects of supplementation on the humoral immune response to challenges against Infl uenza and Newcastle virus (antibody titers) and to SRBC (immunoglobulin production) and also in the weight of liver and main lymphoid organs at slaughter. At the end of the study, the carcass weight was similar between groups and to the reported in other studies for the same age at slaughter. On respect to the responses to viral challenges...(AU)

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