Esse artigo teve como objetivo avaliar o impacto da contaminação por metais dos sedimentos de corrente do Rio São Francisco e de um de seus tributários, Córrego Consciência, na região de Três Marias (Minas Gerais/Brasil), ambos impactados por atividades antrópicas, a partir da metodologia de Balanço das Evidências - BDE, e, dessa forma, prover embasamento para uma decisão de gerenciamento de risco. Para o BDE se utilizou resultados de: concentração de metal nos sedimentos, ensaios de SVA-MES, ensaios de elutriação, ensaios de ecotoxicidade, estudo da comunidade bentônica. Legislação nacional e outras literaturas disponíveis foram utilizadas como critério de avaliação das linhas de evidências. Todas as amostras, exceto pela área de referência, apresentou alguma contaminação. Entretanto, ensaios geoquímicos para estudo da biodisponibilidade demonstraram que a toxicidade não é provável como sugeriram os resultados químicos. Estudos de ecotoxicidade e de estrutura da comunidade bentônica forneceram informações complementares importantes para embasar a tomada de decisão quanto ao gerenciamento ambiental dos sedimentos. Mecanismos de formação de metais volatilizáveis por acidificação foram identificados, podendo atenuar a toxicidade eventualmente verificada. A remoção de fontes ativas de contaminação associada ao Monitoramento da Recuperação Natural pode, portanto, ser suficiente para diminuir o risco à biota, eventualmente identificado nos sedimentos do Rio São Francisco.
The weight-of-evidence - WOE approach was used to assess the environmental impact of sediments contaminated by metals in the São Francisco river and one of its tributaries, Consciência creek, both affected by anthropic activities, in the region of Três Marias (Minas Gerais/Brazil). The assessment provided support to a risk management decision. The WOE was based on bulk metal analysis, AVS-SEM assays, elutriate tests, ecotoxicity assays, benthic community assessment and a comparison for the reference area. Brazilian legislation and other available literature were used as criteria to evaluate the lines of evidence. All samples, except for the reference area, presented some contamination. However, geochemical testing for bioavailability studies showed that toxicity is unlikely as suggested by the chemical results. Ecotoxicity and benthic structure studies provided further information to support decision making. Metal acid volatile sulfide formation mechanisms were identified, which can eventually attenuate metal toxicity observed. The removal of active sources of contamination (for example, from tailings dumps) associated with Monitoring Natural Recovery could be sufficient to eventually lessen the risk of the biota in São Francisco river sediments.
This study investigated the hatching distribution of eggs from broiler breeders of different ages in distinct periods of incubation. Eggs were incubated in a single-stage experimental incubator. A number of 3.510 eggs were distributed into 3 treatments with 13 replicates of 90 eggs each. Treatments corresponded to breeder age: young (34 weeks), intermediate-age (44 weeks) and old (72 weeks) breeders. Eggs were transferred to the hatcher at 432 incubation hours, hatching was first checked at 449 hours, after which the number of hatched chicks was counted every 6 hours up to 515 incubation hours. After each count, hatched chicks were removed from the hatcher. Data were submitted to analysis of variance using measures repeated. A significant interaction between breeder age and incubation time was found. The total period required to hatch all incubated fertile eggs was not influenced by breeder age, which, however, affected hatching distribution. Eggs from old breeders hatched later as compared to young and intermediate-age breeders. More than 71% of the eggs had already hatched at 485 incubation hours, and 94% at 491 hours. Eggs laid by old breeders presented higher infertility and total embryo mortality, resulting in lower hatching percentage.
Este trabalho teve o objetivo de compreender como um ecossistema de córrego que flui desde as nascentes até sua desembocadura dentro de uma cidade, transforma-se de recurso hídrico em fonte pontual de poluição. Foi adotada uma abordagem descritiva multidisciplinar, incluindo a determinação espacial e temporal em escala diária de variáveis físicas, químicas, biológicas e ecotoxicológicas. Os resultados mostraram que a qualidade da água rapidamente diminui com o aumento da intensidade espacial de urbanização, levando o sistema a adquirir características típicas de esgoto bruto já após suas primeiras centenas de metros de curso. Apesar da circulação relacionada à maré junto a desembocadura ser restrita devido às baixas profundidades, foi registrada certa melhora na qualidade da água nessa área. A avaliação multidisciplinar se mostrou útil para obter uma compreensão mais realista do processo de degradação do córrego e para propor medidas de restauração ou mitigação dos impactos.
The aim of this study was to understand how a stream ecosystem that flows from its fountainhead to its mouth inside a city, changes from a water resource to a point pollution source. A multidisciplinary descriptive approach was adopted, including the short-term temporal and spatial determination of physical, chemical, biological and ecotoxicological variables. Results showed that water quality rapidly decreases with increasing urbanization, leading the system to acquire raw sewage attributes even in the first hundred meters after the fountainheads. Despite the tidal circulation near the stream mouth being restricted by shallowness, some improvement of the water quality was detected in this area. The multidisciplinary evaluation showed to be useful for obtaining a more realistic understanding of the stream degradation process, and to forecast restoration and mitigation measures.
The present study had the objective of investigating the performance of broilers housed immediately after hatching or after a 12 or 24 hour of post-hatching holding time. One thousand and six hundred male Ross 308 broiler chicks with an initial body weight of 46 grams were used. These chicks were distributed in a completely randomized experimental design with 5 treatments and 8 replications of 35 birds in each treatment. The treatments in this study consisted of the removal of chicks from the hatchery in three different times: after 480, 492 and 504 hours of incubation. In each one of these times, 280 chicks were removed from the hatchery and immediately housed. Another group of an identical number of chicks of each time remained in the hatchery to be housed at 504 hours after hatching. The chick group corresponding to those hatched at 480 and 492 hours performed better until 7 days. However, no differences in body weight or body weight gain were observed at the end of the study. Feed efficiency, however was worse for the birds hatched and placed at 480 hours. There were no differences among treatments for mortality.
This study aimed to evaluate broiler responses to increases in feed energy (2,870, 3,000 and 3,100 kcal ME/kg) and the inclusion of Acidulated Soybean Soapstock (ASS) when compared to Degummed Soybean Oil (DSO) in feeds from placement to 7 days of age. From 7 to 42 days ASS or DSO were included in diets that contained similar energy and nutrient levels. Metabolizable energy values used to formulate the diets for ASS and DSO were 8,351 and 7,701 kcal ME/kg in the first week and 9,314 and 8,559 kcal ME/kg afterwards, respectively. Diets were based on corn and soybean meal and were fed to 1,600 one-d-old male broiler chicks randomly placed in 40 floor pens. No differences in performance due to fat source were seen at 7 days. However, the increase in energy levels to 3,100 kcal ME/kg reduced feed intake, whereas feed conversion was improved with energy at 3,000 kcal ME/kg. Live performance, and the yields of carcass and commercial cuts were not affected by the type of fat included in the feeds from 7 to 42 days, except for increased body weight at 21 and 35 days with ASS supplementation. Litter moisture at 7, 21, 35 and 42 days was not affected by any of the factors and there were no residual effects of treatments at 21, 35 and 42 days of age. On the other hand, body weight at 35 days was affected by the interaction of diets fed in the first week with those provided afterwards. The results showed that ME values used for DSO and ASS are adequate and that ASS may be used as fat source in broiler feeds from placement to 42 days of age.
Broiler chicks from one incubator hatch within long periods of time, which leads to dehydration and reduction in yolk sac reserves of those chicks that have hatched earlier and potentially impairs early performance. The present research investigated the hatching distribution at intervals of incubation using eggs of different weights within one breeder age or eggs from widely different breeder ages. Eggs from breeders at 27 and 59 weeks of age (54 and 69 g) and from breeders at 40 weeks of age, which were graded as light (58 g) and heavy (73 g), were placed in a commercial incubator. There were a total of 1,184 eggs distributed in four treatments and eight replicates: eggs from 27-week-old breeders (27B), eggs from 59-week-old breeders (59B), light eggs from 40-week-old breeders (40BL) and heavy eggs from 40-week-old breeders (40BH). Replicates were comprised of 37 eggs that were placed in each incubator tray. The treatments were physically separated from each other using a plate. Eggs were transferred to a hatcher after 432 hours of incubation and the first chick hatched at 449 hours of incubation. Afterwards, the number of completely hatched chicks from each replicate was recorded at six-hour intervals until 503 hours of incubation, when the hatchings stopped. Hatched chicks were removed from the trays after each measurement. Data were submitted to an analysis of variance with repeated measures. There was a significant interaction between breeder age and incubation length. The hatching onset of eggs from the old breeders was later compared to young breeders. Hatchability (%incubated eggs) was lower for the old breeders; however, differences in hatchability as a percentage of the hatched eggs were not so evident. Complete hatchability occurred only at 503 hours of incubation; however, more than 90% eggs had hatched 18 hours earlier.
Dois experimentos foram realizados com o objetivo de avaliar o desempenho de frangos de corte no período de 1 a 21 dias alimentados com dietas formuladas nos conceitos de proteína bruta e proteína ideal. No primeiro experimento, foram utilizados 400 pintos machos de um dia de idade da linhagem Cobb, distribuídos em delineamento inteiramente casualizado, com 2 tratamentos (proteína total e proteína ideal) e 5 repetições de 40 aves cada. No segundo experimento, foram utilizados 800 pintos, 400 machos e 400 fêmeas, em arranjo fatorial 2x2 (2 formulações - proteína bruta e proteína ideal e 2 sexos) com 4 tratamentos e 5 repetições de 40 aves cada. As dietas foram formuladas atendendo às exigências estabelecidas pela DEGUSSA (1997). Aos 21 dias, foram avaliados, o ganho de peso, o consumo de ração e a conversão alimentar. No experimento 1, as aves alimentadas com dietas formuladas no conceito de proteína ideal apresentaram maior ganho de peso e maior consumo de ração. No experimento 2, as aves que se alimentaram com a dieta formulada com base da proteína ideal apresentaram melhor ganho de peso e melhor conversão alimentar, não influenciando o consumo de ração. Os resultados demonstraram que as aves alimentadas com dietas baseadas no conceito de proteína ideal apresentam melhor desempenho.
Two experiments were conducted to evaluate the performance of broilers from 1 to 21 days of age fed diets based on the concept of crude protein and ideal protein. In experiment one, four hundred one-day Cobb male birds, were allocated in experimental design involving 2 treatments (crude protein and ideal protein) with 5 replications of 40 broilers each. In experiment two, 800 birds were used, 400 males and 400 females, in factorial arrangement 2x2 (2 concept - crude protein and ideal protein and 2 sex) with 4 treatments with 5 replications of 40 broilers each. The digestible amino acid and total amino acid recommendations were based on DEGUSSA (1997). Data from performance (weight gain, feed intake and feed conversion) were collected. Broilers fed diet based on ideal protein showed greater weight gain and feed intake in experiment 1.In experiment 2 broilers fed diet based on ideal protein showed better weight gain and feed conversion, but feed intake was not affected. The results showed that broilers fed diet based on ideal protein showed better performance.
Foi investigado o efeito da substituição de antibióticos por prebiótico, probiótico e simbiótico em dietas para frangos de corte de 1 a 45 dias de idade. Foram utilizados 750 pintos de 1 dia de idade, distribuídos em cinco tratamentos, sendo: T1-sem aditivos, T2-antibiótico (Olaquindox<FONT FACE=Symbol>â</FONT> e Nitrovin<FONT FACE=Symbol>â</FONT> ), T3-prebiótico (0,2% de parede celular de S. cerevisiae), T4-probiótico (300 ppm de B. subtilis) e T5-simbiótico (T3 + T4). O desempenho dos frangos de 1-45 dias de idade foi influenciado pelos diferentes tratamentos, sendo o melhor ganho de peso observado em aves que receberam o simbiótico, seguido daquelas com antibiótico, prebiótico e probiótico. O pior ganho de peso foi observado nas aves que não receberam qualquer tipo de aditivo na dieta. A conversão alimentar, no período de 1 a 45 dias de idade, também foi influenciada pelo tipo de aditivo. As aves que não receberam suplementação apresentaram pior conversão alimentar quando comparadas com as aves dos demais tratamentos. Os resultados deste experimento permitem concluir que a substituição de antibióticos por simbióticos na ração de frangos é uma alternativa viável, pois não compromete o desempenho das aves, contudo a ausência de aditivos na dieta piora o desempenho das mesmas.
This study was carried out with the objective to test the substitution of antibiotics by prebiotics, probiotics or symbiotics in broiler chickens diet up to 45 days of age. Day-old chicks (n=750) were divided in five treatments, as follow: T1-no additives, T2-antibiotics (Olaquindoxâ e Nitrovinâ ), T3-prebiotic (0.2% de S. cerevisiae cell wall), T4-probiotics (300ppm B.subtilis) and T5-symbiotic (T3+ T4). The performance of broilers up to 45 days of age was influenced by treatments, with better weight gain observed in the birds fed with symbiotics, followed by antibiotcs, prebiotics and probiotics. The worse body weight gain was obtained by the broilers whose diet was not supplemented by any additive. During this period, feed conversion was also affected depending on the additive used, since the birds not supplemented showed the worse results when compared to the birds of the other treatments. The findings of this study suggest that the substitution of antibiotics by symbiotics in broiler chicken diets is an alternative to poultry industry, since no negative effect was found on performance. However, the total absence of additives in the diets worsened the broiler chicken performance.