ABSTRACT Three experiments were carried out to evaluate the levels of digestible valine in diets with reduced crude protein on the performance, carcass yield and muscle fiber diameter of male broilers during the pre-starter (1 to 8 d of age), starter (9 to 21 d of age) and grower phases (21 to 42 d of age). A total of 1,080 chickens in the pre-starter phase, 900 in the starter phase and 864 in the grower phase were distributed in a completely randomized design with six treatments, consisting of a control positive diet (C+) and diets with 2 percentage points (p.p.) reduction of crude protein level and five graded levels of digestible valine (Val), with six replicates of 30, 25 and 24 birds per experimental unit, respectively. The recommended level of TID Val in the low-protein diets for broilers in the pre-starter, starter and grower stages were 1.028; 0.905 and 0.789%, respectively. The reduction of 2 percentage points of the crude protein level in diets based on corn and soybean meal impaired (p ≤0.05) the feed conversion ratio in the starter and grower stages. Likewise, the reduced-protein diets decreased (p ≤0.05) muscle fiber diameter, but did not affect (p> 0.05) carcass and parts yields, or abdominal fat percentage at 42 days.

The aim of this study was to evaluate the supplementation of ethanolic extract of propolis (EEP) in broiler chickens diets on immune responses (humoral and cellular), weight of lymphoid organs and hematological profile. A total of 192 birds, raised in metabolism cages until the 21st day, were distributed in a completely randomised design with six treatments, eight replicates and four birds per experimental unit. The treatments consisted of diets containing 0; 1,000; 2,000; 3,000; 4,000 and 5,000 ppm of EEP. The inclusion of EEP gave a quadratic effect (P < 0.05) for relative weight of spleen and cloacal bursa, with the lowest weights found at the level of 2,946 ppm and 2,985 ppm of EEP, respectively. For the relative weight of thymus no change was observed (P > 0.05). There was no change (P > 0.05) in percentages of lymphocyte, heterophil, basophil, eosinophil and heterophil: lymphocyte ratio with the inclusion of EEP. However, there was a reduction (P < 0.05) in the percentage of monocyte to the inclusion level of 3,000 ppm of EEP when compared to control. The phagocytic activity of macrophages, the average number of phagocytised red cells and nitric oxide production were not affected (P > 0.05). The interdigital response to phytohaemagglutinin showed negative linear and quadratic behavior (P < 0.05) as a function of time and levels of inclusion, respectively, noting the smallest value of the reaction with 3,074 ppm of EEP. The birds showed a linear increase (P < 0.05) of serum antibodies against Newcastle disease, however, when each level of inclusion was compared to the control no difference was observed (P > 0.05). It is concluded that the addition of 1,000 to 5,000 ppm of EEP to the starter broiler diet did not have immunostimulant effect.

Este estudio evaluó la suplementación de extracto etanólico de propóleos (EEP) en dietas de pollos de engorde sobre la respuesta inmune (humoral y celular), peso de órganos linfoides y perfil hematológico. Se utilizaron 192 pollos de engorde, machos, criados en jaulas de metabolismo hasta los 21 días de edad. El diseño experimental fue completamente al azar con seis tratamientos, que consistieron en diferentes niveles de inclusión de EEP (0; 1.000; 2.000; 3.000; 4.000 y 5.000 ppm), con ocho repeticiones y cuatro aves por unidad experimental. La inclusión dietética de EEP provocó un efecto cuadrático (P < 0,05) en el peso relativo del bazo y bolsa de Fabricio, con menores pesos en pollos suplementados con 2.946 y 2.985 ppm de EEP, respectivamente. En el peso relativo del timo no se observó efecto (P > 0,05) de los tratamientos. La inclusión de EEP no alteró (P > 0,05) el porcentaje de linfocitos, heterófilos, basófilos, eosinófilos y la relación heterófilo:linfocito. Hubo reducción (P < 0,05) en el porcentaje de monocitos con la inclusión de 3.000 ppm de EEP en comparación al control. La actividad fagocítica de los macrófagos, número promedio de eritrocitos fagocitados y producción de óxido nítrico no fueron alterados (P > 0,05). La reacción interdigital a la fitohemaglutinina presentó efecto lineal negativo y cuadrático (P < 0,05) en función del tiempo y de los niveles de inclusión, respectivamente, resultando en menor reacción con el nivel de 3.074 ppm de EEP. Hubo aumento lineal (P<0,05) de los niveles de anticuerpos séricos contra la enfermedad de Newcastle al incrementar el nivel de EEP en la dieta; sin embargo, al comparar cada nivel de inclusión del extracto con el control no hubo diferencias (P < 0,05). Se concluye que la inclusión de 1.000 a 5.000 ppm de EEP en la dieta inicial de pollos de engorde no demostró efecto inmunoestimulante.

This study evaluated the performance and the quality and fatty acid profile of eggs from laying hens fed diets containing mixed crude glycerin (MCG; 80% vegetable fat + 20% animal fat). A total of 240 39-week-old Hy-Line W36 laying hens were distributed according to a completely randomized experimental design into six treatments consisting of graded MCG dietary inclusion levels (0, 1.5, 3.0, 4.5, 6.0, and 7.5%), with five replicates of eight birds each. Feed intake linearly decreased (p<0.05) with increasing MCG inclusion levels. The percentages of myristic, palmitic, and α-linolenic acids in the eggs linearly decreased as MCG dietary levels increased (p<0.05), while α-linoleic acid, polyunsaturated fatty acids (PUFA) and ω-6/ω-3 ratio linearly increased. Excreta moisture linearly increased with increasing levels of MCG inclusion (p<0.05). MCG may be included in up to 7.5% in layer feeds without impairing performance or egg quality, but levels up to 5.54% reduce SFA egg content. However, the inclusion of MCG in layer diets increases ω-6/ω-3 ratio in the eggs.

Vitamin K is involved in blood clotting process and plays an important role in bone formation. Thus, this study aimed to evaluate the supplementation of different levels of vitamin K3 on growth performance and bone parameters of broiler chickens. For this purpose, 1,500 broiler chickens were distributed in a completely randomized experimental design. The treatments consisted of a control diet containing 1.6 mg of vitamin K3/kg of diet and 5 levels of vitamin K3 (11.6 mg/kg; 21.6 mg/kg; 41.6 mg/kg, 61.6 mg/kg and 81.6 mg/kg), with 5 replicates and 50 chickens per experimental unit. At 7, 21, and 40 days of age, growth performance (body weight, body weight gain, feed intake and feed:gain ratio) and bone parameters (bone length and diameter, Seedor index and bone strength) were evaluated. The increase in vitamin K3 levels improved the feed intake, body weight and body weight gain in the pre-initial phase. At 40 days old, all performance parameters were similar among the different levels of vitamin K3. At 21 and 40 days of age, bone parameters were impaired as dietary levels of vitamin K3 increased. The results suggest that the recommended level of vitamin K3 in broiler chicken diets is 1.6 mg/kg of diet.

La vitamina K participa en los procesos de coagulación sanguínea y también tiene un importante papel en la formación de los huesos. Así, el objetivo de este estudio fue evaluar la suplementación de diferentes niveles de vitamina K3 sobre el comportamiento productivo y indicadores óseos de pollos de engorde. Se utilizaron 1.500 pollos de engorde, distribuidos en un diseño experimental completamente al azar. Los tratamientos consistieron en una dieta control conteniendo 1,6 mg de vitamina K3/kg de dieta y de 5 niveles de vitamina K3 (11,6 mg/kg; 21,6 mg/kg; 41,6 mg/kg, 61,6 mg/kg y 81,6 mg/kg), con 5 repeticiones de 50 aves/unidad experimental. A los 7, 21 y 40 días de edad, los indicadores de comportamiento productivo (peso promedio, ganancia de peso, consumo de dieta y conversión alimentaria) y los indicadores óseos (longitud y diámetro de los huesos, índice de Seedor y resistencia ósea) fueron evaluados. El aumento en los niveles de vitamina K3 mejoró el consumo de dieta, peso promedio y la ganancia de peso en la fase pre-inicial. A los 40 días de edad, todos los indicadores de comportamiento productivo fueron similares entre los diferentes niveles de vitamina K3. Los indicadores óseos empeoraron a los 21 y 40 días de edad con el aumento en los niveles de vitamina K3. Estos resultados sugieren que el nivel indicado de vitamina K3 en las dietas de pollos de engorde es de 1,6 mg/kg de dieta.