Intégration culture-élevage dans les Cerrados au Brésil : une solution pour des systèmes durables

Les systèmes actuels de production de grains, viande et lait dans la région des Cerrados présentent des problèmes croissants économiques et de production. Une des solutions pour améliorer la production, tout en maintenant ou en améliorant la qualité des sols, consiste à intégrer dans les mêmes exploitations l'élevage et la production de grains, comme la rotation de cultures annuelles et de prairies, en associant ce processus au renouvellement ou à la récupération des pâturages. Ce travail présente, au travers d'expériences conduites chez les producteurs, les possibilités offertes par cette intégration de cultures à cycles courts et de l'élevage. Ces exemples sont choisis de manière à illustrer la variabilité de sols existante (latossols de diverses textures). (Résumé d'auteur

Stress in pacu exposed to ammonia in water

The present study evaluated stress indicators in pacu exposed to ammonia in water under the following conditions: without NH4Cl (0.00 g/L); with 0.0078 g NH4Cl/L; and with 0.078 g NH4Cl/L (pH 8.3 and 27 ºC). After the salt dilution the water flow was interrupted and reestablished in 24 hours. Sampling occurred prior to the addition of NH4Cl (control) and after 12, 24 and 48 hours. Glycaemia increased only in fish with the highest salt concentration when compared with group control, regardless of time, and at 24 hours, regardless of treatment. Plasma ammonia, highest in fish exposed to the highest NH4Cl concentration, decreased progressively up to 48 hours. Plasma chloride only decreased in fish not exposed to salt when compared with control and osmolality increased after 24 hours. Hematocrit (Ht), number and volume of erythrocytes and hemoglobin did not change when NH4Cl was added; Ht decrease was reported after 12 hours, but it was not followed by the other blood parameters. The results show tolerance of the pacu to ammonia in the environment

Feed training of giant trahira fingerlings fed diets containing different levels of vitamin C

The objective of this work was to evaluate suplemenation of vitamin C during feed training of giant trahira fingerlings. An experiment was established in a complete random design with seven treatments (0.0, 17.5, 52.5, 87.5, 122.5, 175.0 and 350.0 mg vitamin C/kg diet) and four repetitions. Giant trahira fingerlings (2.8 ± 0.2 cm) were distributed in 6-L aquaria at the density of 6 fish/L. A basal diet was formulated with 44.0% of crude protein and vitamin C and bovine heart were added in it daily. After 20 days, biometry of fish for evaluation of weight and length gains, rates of survival and cannibalism and uniformity of final length and for macroscopic observations of clinical signs of deficiency or excess of vitamin was carried out. After biometry evaluation, ten fish from each tested diet were collected for analysis of the fatty acid profile which was compared to profile of fish at the same life stage fed forage fish collected from breeding fishponds. Data on growth performance and fatty acid profiles were submitted to analyses of polynomial regression and uniformity of the final length was evaluated by the Bartlett test. There was a significant difference only for uniformity in final length and fatty acid profile of the carcass. Supplementation with 52.5 mg vitamin C/kg diet provided a greater uniformity of the final length of the fish. Fish from breeding fishponds presented lower concentration of PUFA (polyunsaturated fatty acids) and higher concentration of saturated fatty acids compared to fish trained to accept dry diets.Com este trabalho objetivou-se avaliar a suplementação de vitamina C durante a fase de condicionamento alimentar de alevinos de trairão. Um experimento foi estabelecido em delineamento inteiramente casualizado com sete tratamentos (0,0; 17,5; 52,5; 87,5; 122,5; 175,0 e 350,0 mg de vitamina C/kg de ração) e quatro repetições. Alevinos de trairão (2,8 ± 0,2 cm) foram distribuídos em aquários de 6 L, na densidade de 6 peixes/L. Uma ração basal foi confeccionada com 44,0% proteína bruta, e diariamente foi adicionada vitamina C e coração bovino. Após 20 dias, realizou-se biometria dos peixes para avaliação do ganho de peso e do comprimento, das taxas de sobrevivência e canibalismo e da uniformidade do comprimento final e para observações macroscópicas de sinais clínicos de deficiência ou excesso da vitamina. Após a biometria, dez peixes de cada dieta testada foram coletados para análise do perfil de ácidos graxos e este perfil foi comparado ao perfil de peixes, na mesma fase de vida, alimentados com peixes forrageiros coletados de viveiros de criação. Os dados de desempenho produtivo e perfil de ácidos graxos foram submetidos a análise de regressão polinomial e a uniformidade do comprimento final avaliada pelo teste de Bartlett. Houve diferença significativa apenas para a uniformidade em comprimento final e perfil de ácidos graxos da carcaça. A suplementação com 52,5 mg de vitamina C/kg de ração proporcionou maior uniformidade do comprimento final dos peixes. Os peixes dos viveiros de criação apresentaram menor concentração de PUFA (polyunsaturated fatty acids) e maior de ácidos graxos saturados em comparação aos peixes condicionados a aceitar dietas secas