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La cría de roedores tropicales (Thryonomys swinderianus y Atherurus africanus) como fuente de alimento en Gabón, África CentralJori Massans, Ferran 18 May 2001 (has links)
Gabón es un país de Africa ecuatorial con uno de los mayores consumos de carne de caza del continente. Los roedores silvestres se encuentran entre las especies más apreciadas y con mayor valor comercial. Con el objetivo de estudiar la viabilidad técnica de cría de aulácodos (Thryonomys swinderianus) en Gabón, se estableció una granja demostrativa a partir de animales importados de Benin. Los resultados zootécnicos no presentaron grandes diferencias respecto a los parámetros descritos en Benin. En 19 meses, se obtuvieron 130 camadas de 4,06 crías /parto, 1,86 partos/hembra y 6,77 crías destetadas/hembra /año. A partir de 1995, se inició la fase de difusión de tecnología a criadores locales. En las granjas, se observó una prolificidad elevada (4,47 crías / camada), pero una productividad numérica baja (2,48 destetados /hembra /año; n=90 partos). La mortalidad global y la mortalidad al destete fueron elevadas (22 y 31% ; n=79 partos). Los resultados demuestran que la cría del aulácodo es técnicamente viable a pesar de que existe un amplio margen de mejora entre los criadores y dificultades de asimilación de las técnicas. A pesar de que esta producción aun no llega a sustituir el enorme volumen de carne de caza comercial, presenta un buen potencial para la producción de proteína animal en áreas periurbanas de Gabón y para la generación de ingresos para el criador.También se estudió la morbilidad y mortalidad en la granja experimental de Libreville durante un periodo de 21 meses. El 28% de los casos de mortalidad se produjeron en animales jóvenes, el 42% en subadultos y el 28% en adultos La principal causa de mortalidad fueron los traumatismos, (29% de los casos), seguidos septicemia (12%), patologia respiratoria (10%). El seguimiento realizado permitió identificar algunas diferencias respecto otros estudios y establecer las primeras referencias sobre la patología de este animal en África Central. También permitió describir casos de neoplasia identificados por primera vez en esta especie. Por ultimo, se investigo el potencial productivo de Atherurus africanus mediante un analisis de 22 aparatos reproductores de hembras silvestres. Todas las hembras gestantes presentaron un solo feto u embrión y el numero de cuerpos luteos (CL) fue de 19,9 ± 5,4 (diámetro = 1709 ± 421 µm), incluyendo un CL de gestacion (diámetro medio = 4821 µm ± 1364 µm ). La media de tejido luteal activo fue elevada (115,6 mm3). Los resultados confirman que el ateruro salvaje es también una especie mono-embrionica, pero poliovular, sugiriendo una importante mortalidad ovocitaria o embrionaria en la cual se pierde mas del 95% del material biológico. Esto sugiere que el ateruro necesita grandes cantidades de progesterona para mantener la gestación. También, evidencia la baja capacidad reproductiva de la especie. / Gabon is an equatorial country, with one of the highest bushmeat consumption in Africa. The most favourite and commercially valuable species include wild rodents.With the aim to study the technical feasibility of cane rat (Thryonomys swinderianus) farming in Gabon, a demonstrative farm was established in the outskirts of Libreville with animals adapted to captivity. Among 130 litters, we obtained 4,06±1 young/litter, 1,86 litters/female and 6,77 weaned animals/female.Since 1995, an extension programme among local farmers was initiated. A survey in 1998, allowed the record of a high mortality (global, 19% and pre-weaning, 31%) but reproduction parameters (4,47 young/litter) comparable to those obtained in the experimental farm. Numeric productivity was 2,48 weaned/female/year. This results suggest that cane rat farming in Gabon is feasible also at a farmer's level. However, there is a large margin of improvement due to some difficulties in assimilation of animal husbandry techniques. Despite a low level of exploitation, cane rat farming has the potential to provide an alternative source of protein to commercial hunting and a substantial source of income for the farmer living in peri-urban areas.The causes of morbidity and mortality of farmed cane rats in Gabon were studied during 21 months through the survey of 94 postmortem examinations of 546 animals. Most of the cases occurred in subadults (42%), while non weaned young and adults were equally represented with 28% of the cases. Average monthly mortality was 2 ,5%. The main cause of mortality identified was trauma (29% of the sample), followed by septicaemia (12%) and respiratory problems (10%). Fifteen percent of cases were represented by digestive, urinary and reproductive disorders and 3% to other causes. No diagnosis could be reached in 28% of cases.In order to assess the prolificity of Atherurus africanus in the wild, 22 female carcasses were obtained from markets in Libreville during 2 years. Reproductive tracts were examined for the presence of embryos or foetuses. The ovaries were histologically examined. Morphology and constituent cell types of the ovaries were similar to those described for other hystricognath rodents. All pregnant females had only one embryo or foetus and 20±5 cyclic corpora lutea (CL), including one CL of pregnancy at least 2,8 times larger in diameter and 9±7 accessory CL. The mean number of antral follicles in adult females was 25±10. The study confirms that the brush-tailed porcupine is a mono-embryonic but polyovular species, suggesting important ovum mortality. This unusual reproductive feature in mammal species gives this rodent a low reproductive productivity which compromises the cost effectiveness of its captive breeding. Moreover, this species could be more susceptible to the effects of hunting than generally thought.
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Physiologie digestive de l'aulacode (Thryonomys swinderianus) en croissance et impact des teneurs en fibres et céréales de la ration sur la santé et les performances zootechniques / Digestive physiology of the growing cane rat (Thryonomys swinderianus) and impact of fibre and cereal content of the diet on health and zootechnical performanceYapi, Yapo Magloire 14 March 2013 (has links)
L’aulacode (Thryonomys swinderianus) est un rongeur herbivore récemment domestiqué en Afrique pour la production de viande. Quelques études antérieures ont portés sur l’alimentation de cet animal, dans le but d’améliorer la productivité des élevages. A ce jour, nos connaissances sur la digestion et les besoins nutritionnels de cet animal sont encore très parcellaires. Le premier objectif de notre étude était d’améliorer nos connaissances sur la physiologie digestive de l’aulacode en croissance, en particulier en relation avec les apports de fibres alimentaires, avec pour finalité de proposer des recommandations nutritionnelles en fibres pour optimiser la croissance et la santé digestive de cet animal. Notre second objectif était d’analyser les effets d’une diminution du ratio protéines digestibles / énergie digestible parallèlement à une hausse des apports d’amidon, sur la digestion et les performances. La finalité était d’analyser les possibilités de formuler un aliment complet moins onéreux pour les éleveurs et qui respecte les besoins de l’aulacode en croissance. Notre étude a permis de savoir que le caecum est le compartiment digestif le plus important du jeune aulacode entre 1 et 3 mois d’âge, avec plus de 40% du contenu digestif total. L’activité microbienne caecale (100 mM d’acides gras volatils totaux (AGVt) par gramme de contenu frais) est élevée, et similaire à celle des ruminants ou d’autres herbivores monogastriques. Le profil fermentaire est caractérisé par une prédominance de l’acétate (75 % des AGVt) et un ratio propionate / butyrate supérieur à 1. Le pyroséquençage 454 de l’ADN16S bactérien a permis de caractériser le microbiote caecal. Au sevrage, nous observons une prédominance du phylum des Bacteroidetes, avec 51 % d’abondance relative, alors que le phylum des Firmicutes devient majoritaire (50%) à 3 mois d’âge. Le microbiote caecal est caractérisé par la présence de genres souvent identifiés dans d’autres écosystèmes digestifs d’herbivores, tels que : RC9 (2 à 8%), Parabacteroides (1 à 8%), Prevotella (3 à 6%) et Xylanibacter (1%), Erysipelotrichaceae Turicibacter (1 à 7%), Lachnospiraceae Incertae_Sedis (4 à 5%), Ruminococcaceae Incertae_Sedis (1 à 2%) et Ruminococcus (1 à 3%). D’autres genres, absents chez des espèces voisines comme le lapin et le cobaye, semblent plus spécifiques de l’aulacode, tels que Termite_Treponema_cluster (1.7 à 2.2%) et Treponema (7 à 13%), du phylum des Spirochaetes. L’analyse des performances zootechniques indique qu’un taux de fibres compris entre 17 et 21 % d’ADF représenterait un bon compromis entre santé digestive et croissance de l’aulacode après son sevrage. Descendre au dessous de 6 g de protéines digestibles par MJ d’énergie digestible, via une hausse importante des apports d’amidon et une baisse importante du taux de protéines brutes (en dessous de 11 %) et de fibres, est préjudiciable à la croissance des animaux. / The cane rat or grasscutter (Thryonomys swinderianus) is a rodent herbivore recently domesticated in Africa for meat production. Some previous studies focused on the feeding of this animal, in order to improve the productivity of farms. To date, our knowledge of digestion and nutritional requirements of this animal are still very scarce. Our first objective was to improve our knowledge of digestive physiology of the young grasscutter, particularly in relation to dietary fibre supply, in order to improve the recommendations for dietary fibre content of diets to optimize growth and digestive health. Our second objective was to analyze the effects of a decreased digestible protein / digestible energy ratio, along with an increased intake of starch, on digestion and performances. The final aim was to analyze the possibilities to formulate a complete feed, cheaper for farmers and that meets the requirements of the young grasscutter. Our study found that the caecum is the most important digestive compartment of the young grasscutter between 1 and 3 months of age, with more than 40% of the total gut contents. The caecal microbial activity (100 mM of total volatile fatty acids (VFA) per gram of fresh content) is high and similar to that of ruminants or other herbivorous monogastric animals. The fermentation profile is characterized by a predominance of acetate (75% of total VFA) and a propionate / butyrate ratio greater than 1. A pyrosequencing of bacterial 16S-DNA was used to characterize the caecal microbiota. At weaning (one month), we observe a predominance of the Bacteroidetes phylum, with 51% of relative abundance, whereas the Firmicutes phylum becomes predominant (50%) at 3 months of age. Caecal microbiota is characterized by the presence of genera often identified in other digestive ecosystems of herbivores, such as: RC9 (2-8%), Parabacteroides (1-8%), Prevotella (3.6%) and Xylanibacter (1%), Erysipelotrichaceae Turicibacter (1-7%), Lachnospiraceae Incertae_Sedis (4-5%), Ruminococcaceae Incertae_Sedis (1-2%) and Ruminococcus (1-3%). Other genera, absent in related species such as rabbits and guinea pigs, seemed more specific of the grasscutter, such as Termite_Treponema_cluster (1.7-2.2%) and Treponema (7-13%) of the Spirochaetes phylum. The analysis of growth performances indicated that a dietary fibre content between 17% and 21% of ADF represents a good compromise between digestive health and growth of the grasscutter after weaning. Decreasing below 6g of digestible protein / MJ of digestible energy, via a high increase in starch intake and a significant decline in crude protein content (below 11%) and fibre, is detrimental to the growth of animals.
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