Effect of environmental humidity and ventilation rate on the microenvironmental humidity and ammonia concentration in individually ventilated cages (IVC) / 中国比较医学杂志

Objective To assess the changes of humidity and ammonia concentration in rat and mouse individually ventilated cages (IVC) based on macroenvironmental humidity and air ventilation changes .Methods Three kinds of rat and mouse IVC in barrier facilities were set as research objective .The changes of micronvironmental humidity and ammonia concentration at 40 times/h and 60 times /h air changes were detected continuously for a 7-days-cycle relative to low (40%), moderate (50%), and high (60%) macroenvironmental humidity.Results Mouse and rat IVC with 40 times /h air changes under low macroenvironmental humidity condition , mouse IVC with 40 times/h and rat IVC with 60 times/h air changes under moderate macroenvironmental humidity condition , mouse IVC with 60 times /h air changes under high macroenvironmental humidity condition , basically meet the GB14925-2010 requirements.While under macroenvironmental high humidity condition, the microenvironments of rat and mouse IVC with 60 times/h air changes could not satisfy the requirements.Conclusions The environmental humidity and ventilation frequency are the key index of IVC microenvironment.Only on the basis of external environment conditions to set up reasonable IVC ventilation frequency in order to better maintain the IVC microenvironment so that to achieve the goal of effective management .

Formation of aerobic granular sludge under adverse conditions: Low DO and high ammonia.

In this study, two adverse environments: low dissolved oxygen (DO) and high ammonia concentration, were employed to investigate the morphology, interspecies quorum sensing, extracellular polymers (EPS) characterization and microbial communities in the formation of aerobic granular sludge. Results showed that low DO could promote filamentous bacterial outgrowth. Under high ammonia concentration aerobic granular sludge (AGS) could still be cultivated, although it was looser and lighter than the control group. During the early stage of the AGS cultivation process, AI-2 activity reached a peak value in all three reactors, and ultrasonic pre-treatment was not beneficial to the release of AI-2. During AGS formation, the production of polysaccharide exhibited increases from 12.2 % to 40.3 %, 49.6 %, and 29.3 %. And PS in R2 was the highest as the result of sludge bulking. PS/PN was 1.5~8 in the three reactors. Three-dimensional EEM fuorescence spectroscopy variation indicated the change of protein in EPS, and the highest intensity of Peak T1 was obtained. The location shift of Peak T1 was not obvious, and Peaks A, C, and T2 shifted toward longer wavelengths (red shift) of 5~60 nm, or shorter wavelengths (blue shift) of 10~25 nm on the emission scale and / or excitation scale in all three reactors. This provided spectral information on the chemical structure changes. Bacteria in R3 had the highest species diversity, and all bacteria in b-Proteobacteria were identified as genus Thauera, which suggested that simultaneous nitrification and denitrification occurred in R3. The filamentous bacteria in seed sludge and R2 were species-richer. There was a low abundance of filamentous bacteria in R1 and R3, which contributed to the granule structure stability.

Influência de subprodutos de oleaginosas sobre parâmetros ruminais e a degradação da matéria seca e da proteína bruta / Influence byproducts of oleaginous on ruminal parameters and degradation of dry matter and crude protein

Avaliou-se o efeito da adição de subprodutos de oleaginosas na dieta de ovinos em substituição ao farelo de soja. Foram distribuídos quatro ovinos Santa Inês, com peso corporal de, aproximadamente, 40kg, canulados no rúmen, em quadrado latino (4x4), com quatro dietas e quatro períodos, analisados por regressão para a avaliação da degradação ruminal, dos valores de pH e das concentrações de nitrogênio amoniacal in vivo. Os subprodutos foram as tortas de amendoim, girassol e soja, em dietas isonitrogenadas, com 70% de concentrado e 30% de volumoso (feno de tifton). Não foi observado efeito da interação tempo x dieta para os valores de pH e concentração ruminal de nitrogênio amoniacal (P>0,05). O pH apresentou valor médio de 6,2. As concentrações ruminais de nitrogênio amoniacal não foram afetadas, com valor médio de 29,9mg/dL. Não foram observadas diferenças (P>0,05) nas taxas de degradação da matéria seca e na degradabilidade potencial.

The aim of this work was to evaluate the introduction of oleaginous byproducts in sheep feeding as a replacement for soybean meal. Four sheep weighing 40kg, with cannulated rumen were selected in a Latin Square (4x4) design, with for diets and four periods analyzed by regression for ruminal degradability evaluate, pH values and ammonia nitrogen concentration in vivo. Byproducts were the following cakes: peanut, sunflower and soybean, in isonitrogenous diets with 70% concentrate and 30% roughage (tifton hay). There was no effect of diet x time interaction for pH and ruminal concentrations of ammonia nitrogen (P>0.05). The average pH value was 6.2. Ruminal concentrations of ammonia nitrogen were not affected, and had an average value of 29.9mg/dL. There were no differences (P>0.05) in DM degradation and degradability rates. The use of high degradability protein sources, such as soybean cake and peanut cake, proved to be an interesting alternative to replace soybean meal.