R. Delgado

Effect of level of soluble fiber and n-6/n-3 fatty acid ratio on performance of rabbit does and their litters

The aim of this work was to study whether the dietary supplementation with soluble fiber (SF) and the reduction of the n-6/n-3 fatty acid ratio or the combination of both influences the survival, body and milk composition, and reproductive performance of rabbit does during the first four parturitions. Four diets in a 2 × 2 factorial arrangement were used with two levels of SF (7.8 vs. 13.0, on dry matter [DM] basis; high soluble fiber [HSF] and low soluble fiber [LSF]) and two different n-6/n-3 fatty acid ratios (13.4/1 vs. 3.5/1). Nulliparous does (24/diet) were inseminated 11 d after parturition. Body chemical composition and energy content of rabbit does and their performance, litter growth, and milk production were measured between birth and weaning (25 d) along four parturitions, and milk composition and fecal digestibility were also recorded. The proportion of total removed does decreased in HSF respect to LSF groups (22.9 vs. 50.0%; P = 0.005), and it tended to decrease in LSF groups when the n-6/n-3 ratio increased and in HSF groups when the n-6/n-3 ratio decreased (P = 0.059). The increase of the level of SF reduced the digestible crude protein (CP)/digestible energy ratio (by 4%; P < 0.001) and improved the digestibility of all fibrous fractions (P < 0.001). The reduction of the n-6/n-3 ratio reduced the total dietary fiber digestibility in rabbit does fed LSF diets, but it had no effect in those fed HSF diets (P = 0.043). Treatments had no effect on average daily feed intake among parturitions (P = 0.16), but the digestible CP intake among parturitions was lower in HSF than in LSF groups (P = 0.003). Treatments had no effect on the total number of kits born, litter or average kit weight at birth, or litter size at weaning, fertility, feed efficiency, total milk production, and body chemical composition and energy content of rabbit does (P ≥ 0.29). The average weight of kits at weaning of LSF_Hn-6/n-3 and HSF_Ln-6/n-3 groups decreased by 6% compared with those from the other two groups (P = 0.030). The reduction of the dietary n-6/n-3 ratio increased the milk fat content by 12% with no effect on protein and DM content (P = 0.031). The proportion of milk odd fatty acids and saturated fatty acid increased in rabbit does fed the HSF diets compared with those fed LSF diets (P ≤ 0.037) with no effect of the n-6/n-3 fatty acid ratio. In conclusion, SF reduced the replacement rate of rabbit does with no effect of the n-6/n-3 ratio, while both dietary factors modified milk composition and fatty acid profile with minor influence on litter productivity.

The effect of cellobiose on the health status of growing rabbits depends on the dietary level of soluble fiber

The aim of this study was to examine whether the combination of dietary soluble fiber and cellobiose exerts a synergistic effect on growth performance, health status, fermentation traits, and immune response in rabbits. Six treatments in a 3 × 2 factorial arrangement were used: 3 cellobiose concentrations in drinking water (0.0, 7.5, and 15.0 g/L) × 2 dietary levels of soluble fiber (84.0 and 130 g/kg DM, for the low soluble fiber [LSF] and high soluble fiber [HSF] diets, respectively). A total of 318 young rabbits (53/treatment) were weaned at 34 d of age and had ad libitum access to feed and water. At 46 d of age, 9 rabbits/treatment were slaughtered and ileal and cecal digesta were collected to analyze VFA profile and the immune response in the cecal appendix mucosa. At 48 d of age, the cellobiose supplementation was withdrawn and the experimental diets were replaced by a standard commercial diet until 61 d of age. From 34 to 48 d of age, there was a linear increase of mortality with the level of cellobiose in the HSF group (0% vs. 17.1%; P = 0.017). In contrast, a quadratic effect of cellobiose level on mortality was observed in the LSF group, the rabbits offered 7.5-cellobiose showing the lowest mortality (5.7% vs. 21.4%; P = 0.030). Cellobiose level had a quadratic effect on ADFI, ADG, and G:F in this period (P ≤ 0.047), with the 7.5-cellobiose groups having the best growth performance. In contrast, only minor changes on these traits were observed from 48 d of age onwards. Cellobiose level influenced quadratically the ileal VFA concentrations (P = 0.014), showing the maximal value in the 7.5-cellobiose groups. In rabbits fed 7.5-cellobiose-LSF, a change of acetate to propionate, butyrate, and valerate was observed in the ileum. Increasing cellobiose levels reduced linearly cecal VFA concentrations in HSF fed rabbits, but no effect was detected in LSF groups (P = 0.046). The level of soluble fiber increased VFA concentrations in both the ileum (by 22%; P < 0.001), and the cecum (by 11%; P = 0.005). The relative gene expression of IL-6, IL-10, TNF-α, iNOS, MUC-1, and toll-like receptors (TLR-2 and TLR-4) in the cecal appendix increased linear and quadratically with increasing levels of cellobiose (P ≤ 0.063). In conclusion, in rabbits fed LSF diets, a dose of 7.5 g cellobiose/L drinking water would be recommended, whereas these levels of cellobiose supplementation should be avoided in rabbits fed HSF diets.

Evolución con la edad de los mecanismos de barrera intestinal

Se destetaron 106 gazapos de 20 camadas a los 26 d de edad con un peso de 429 ± 57 g y se sacrifico 1 animal por camada a los 26, 31, 38, 45 y 52 d de edad. La longitud de las vellosidades intestinales y la profundidad de las criptas en el yeyuno se redujeron entre los 26 y los 31 d en un 26 y 9% respectivamente. De los 31 a los 38 dias se observo un aumento tanto de la longitud de las vellosidades como de las criptas. A partir de esta edad no se observaron cambios en las vellosidades, que mostraron valores similares a las determinadas en el destete, mientras que las criptas siguieron aumentando ligeramente (9%). El grado de similitud de la microbiota cecal entre animales de la misma edad (que vario entre un 89, 1 y un 95,3%) fue superior al grado de similitud entre animales de diferentes edades (que vario entre un 82,3% y un 92,5%). La variabilidad en la composicion de la microbiota fue menor a los 45 y 52 d de edad (mostrando un grado de similitud del 92,5% entre ambas edades) en comparacion con la observada entre las primeras edades (26, 31 y 38 d, que vario entre 82,3 y 86,7%). Los menores grados de similitud se observaron entre los animales lactantes y los animales de 31 y 38 d de edad.

Efecto de la fibra soluble sobre los parámetros productivos, y algunos criterios digestivos en conejos alrededor del destete.

El objetivo de este trabajo fue estudiar el efecto de la fraccion soluble e insoluble de la pulpa de remolacha (PR) sobre la fisiologia digestiva en gazapos tras el destete. Se formulo el pienso control (C) con el nivel de fibra soluble mas bajo (3%) y la dieta SBP con el nivel mas alto (9%). Las fracciones soluble e insoluble de la PR fueron estudiadas por separado sustituyendo el almidon o la fibra insoluble de la dieta C por las pectinas de PR (Betapec RU 301) o la fibra insoluble de la PR, respectivamente, obteniendo asi las dietas Pectin y InsSBP. Los 4 piensos tuvieron niveles similares de fibra insoluble (FND 33%) y proteina (16% MS). Se utilizaron 196 gazapos, destetados con 25 dias de edad, bloqueados por camada y asignados al azar a los 4 tratamientos. Tras 10 d los animales fueron sacrificados y se determino el peso del aparato digestivo, la viscosidad ileal, el pH cecal y la morfologia intestinal. Los pesos del ciego y del tracto digestivo fueron mayores (P<0,05) en los animales de los tratamientos InsSBP y SBP comparados con los tratamientos C y Pectin, siendo intermedio el peso del ciego de los animales alimentados con el pienso Pectin. Estos ultimos mostraron el peso de estomago el mas bajo (P<0,05). Los valores del pH cecal mas elevados han sido registrados en los animales alimentados con el pienso control, mientras que los mas bajos se registraron con la dieta InsSBP, siendo los valores de las dietas Pectin y SBP intermedios. Los gazapos alimentados con el pienso SBP mostraron la relacion villi/cripta mas elevada y aquellos alimentados con el pienso control la mas reducida, mientras que el resto de animales de los tratamientos Pectin y InsSBP mostraron valores intermedios. La inclusion en la dieta de conejos tanto de la PR como cualquiera de sus fracciones fibrosas (insoluble y soluble) aumenta la viscosidad ileal respecto al pienso control (P<0,05), aunque los valores mas elevados fueron encontrados en los animales alimentados con el pienso Pectin. El pienso SBP mostro valores intermedios entre los piensos Pectin y InsSBP. Igualmente, el numero de las celulas caliciformes ha tenido una tendencia similar a estos resultados. En conclusion, la fraccion insoluble ejerce mas influencia en el peso del aparato digestivo y la acidez del ciego. La fraccion soluble afecta mas a la viscosidad y el numero de celulas caliciformes, mientras que ambas fracciones muestran un efecto aditivo sobre la relacion villi/cripta.

Análisis multivariante de los horizontes orgánico-minerales de los suelos del Parque Natural de Sierra Mágina (Jaén)

Soils are described normally using a great number of properties (variables). This generates a great quantity of data not easily understandable in a direct way. Consequently, multivariate analysis is necessary to support and confirm impressions and interpretations of investigations in field and laboratory. In the present work we quantify, through multivariate analysis, the relative influence of the different factors of soil formation that act on the soil system. We have studied 203 organo-mineral horizons, sampled to a depth between 0 and 25 cm of soils in the Sierra Magina natural park (Jaen, Spain). The studied soils are from calcareous rocks. Five factors were found to be significant and showed that the organic carbon accumulation, decarbonatation and the argillization/rubefacction, as internal variables, and the hill slope, as external variable, they are those which explain a greater percentage of the natural variability of the soil system.