西芹净化畜禽养殖废水效果研究

通过西芹在不同浓度养殖污水中的生长,研究西芹生长情况及其对畜禽养殖污水净化效果,为利用养殖污水开展西芹水培提供数据支撑。结果表明:西芹均能在稀释20～200倍养殖污水中良好生长。稀释30倍养殖污水中的西芹的生物量最高为31.50 g,且对养殖污水的降解效率也较高,COD为80.54%,氨氮为85.39%,总磷为78.33%。综合西芹生物量和对养殖污水的降解效率,稀释30倍和40倍的养殖污水最适宜西芹生长,既达到了资源化利用的目的,又实现了减量化处理理念。     

载镁水葱生物炭对水体中磷酸盐吸附性能

以水葱为原料,氯化镁为改性剂制备了生物炭,研究了镁改性水葱生物炭对水中磷的吸附性能,利用等温吸附模型和动力学模型揭示吸附行为,结果表明,载镁水葱生物炭对P的理论最高等温吸附量为45.58mg/g,吸附过程为符合Freundlich模型的多分子层吸附;动力学吸附模型更符合准一级模型.     

生物法降解黄曲霉毒素B_1的机理研究进展

黄曲霉毒素B_1是由寄生曲霉、黄曲霉等真菌产生的次级代谢物,具有极强的致畸、致癌等毒性,不仅对人和动物健康构成严重的威胁,而且也给食品和饲料工业带来巨大的经济损失。如何消除黄曲霉毒素B_1的污染依然是目前学者迫切要解决的重点问题。相比理化法消除黄曲霉毒素B_1的缺点和局限,生物法降解具有安全、高效和绿色环保等优点,使其成为更具有潜力的解毒方法。本文主要对生物吸附作用和生物酶解作用降解黄曲霉毒素B_1的机理及降解产物的结构分析进行了论述。     

妊娠绵羊安氟醚药代动力学研究

本文应用气相色谱测定妊娠绵氟醚吸入麻醉期间血药浓度和终末吸气浓度，并研究了安氟醚在妊娠绵羊体内药代动力学过程。经适当动力学模型的建立，分别描述具动力学特点，药代动力学研究表明：安氟醚在妊娠绵羊体内血液药物浓度时间规律为：Ｃ＝１２．４８３２９（ｅ＾－０．０３４４９６４ｔ－ｅ＾－０．０３２６２４２３ｔ）安氟醚吸入后药时曲线符合一级吸收一室开放性模型。动力学参数分别为：消除相生物半衰期（ｔ１／２β）＝２     

菲对水生动物繁育和生长的影响及机理

菲(Phe)是一种典型的多环芳烃类(PAHs)化合物,能致毒、致畸和致癌等,极易在水环境中累积,并可通过食物链传递,难以代谢降解,是全球普遍存在的持久性有机污染物,严重威胁人类和水生动物健康。本文主要综述菲对水生动物繁殖、发育和生长的影响及机理,旨在更深入研究之,有效地控制和防治菲对水生动物的危害,为保护水生生物和生态环境提供参考。     

生物过滤器可以缓解异味和空气污染

科学验证,生物过滤器是一种可有效降低异味和其他气体排放的设备,适用于机械通风的畜舍设施和粪便储存单元。生物过滤器的原理是:将有害气体吸收到生物膜当中,再由微生物降解为水、二氧化碳和盐,微生物可利用降解过程产生的能量和养分实现生长、繁殖。设计良好的生物过滤器可降低硫化氢(H2S)、氨气(NH3)的含量。有关生物过滤器的研究正在积极开展,未来几年关于污染物的减排效率、生物过滤器媒介、配置以及维护方面将会出现更多进展,其他潜在效益还包括抑制病毒的空气传播和温室气体(GHG)的排放。     

头孢噻呋-大蒜素脂质体在大鼠体内的药代动力学

对头孢噻呋与大蒜素单一、配伍及其配伍后脂质体的药代动力学进行研究,采用高效液相色谱法测定给药后不同时间的血药浓度.用BAPP2.0药代动力学分析软件对所测得的结果进行分析,得出以下药代动力学结果:在大鼠体内均呈一室代谢模型.脂质体中药物的半衰期大于单一的药物半衰期,脂质体中药物的吸收速率常数Ka明显大于消除速率常数Ke(Ka头孢噻呋=6.29 h-1> Ke头孢噻呋=1.03 h-1;Ka大蒜素=1.12 h-1> Ke大蒜素=0.11 h-1),说明脂质体中药物的吸收迅速.吸收速率大于消除速率,可以使药物在体内迅速达到有效血药浓度以后维持较长的作用时间.结果表明,头孢噻呋-大蒜素脂质体肌肉注射缓释效果明显.     

我国黄牛数量发展的灰色系统模型

一般地说,生物的数量增长与生物的数量成正比,或者说,生物的相对生长速率是一个常数。显然,这种认识是假定生物生活在“理想环境”之中。而生物的现实生活环境中,有许多因素在削减着其增长速度。可是,我们并不大清楚这些具体因素的具体影响。这种含有未知因素又含有已知因素的系统称为灰色系统。本文试图用灰色系统模型来建立我国黄牛数量发展的动态方程,以供其它决策之用。     

五指山猪(WZSP)近交系生长曲线分析与拟合的研究

畜禽生长曲线的分析和拟合是研究畜禽生长发育规律的主要方法之一。生长曲线可描述动物体重随年龄增加而发生的规律性及连续性变化过程。生长曲线模型（growth curve model，GC）是在研究生物的某指标随时间的增长而变化建立的一种模型，在生物中有广泛的应用。Brody（1954）提出了生长曲线的二阶段性，即生长前期自加速阶段和生长后期自抑制阶段，并分别用不同的数学模型加以描述。以后又建立了Logistic模型、Gompertz模型和Richards模型。     

水生植物在猪场废水净化中的耐污性研究

本试验以凤眼莲,水蕹菜、生菜作为供试植物对经过稀释后的厌氧发酵水做后续处理,在试验中,以CODcr为参照。将原水稀释成2个浓度梯度,170～230mg／L、400～450mg,／L。以考察3种植物对污水的耐污性及净化能力。试验表明：在170～230mg／L8度T3种植物均表现出了良好的生长能力及高降解率。水蕹菜对污水总磷降解率达到91％,对污水氨氮降解率达到98％：生菜对污水CODcr降解率达到64％。在400～450mg／L梯度下,凤眼莲逐步枯萎直至死亡。而水蕹菜及生菜生长良好,表现出了较强的耐污能力。水蕹菜对污水总磷降解率达到95％,对污水氮氮降解率达到99％：生菜对污水CODcr降解率达到80％。     

Studies on the pharmacokinetics of cisatracurium in anesthetized dogs: in vitro–in vivo correlations

Cisatracurium undergoes primarily temperature and pH-dependent Hofmann elimination in humans. This study was conducted to describe the pharmacokinetics of cisatracurium in anesthetized dogs and determine whether its in vitro degradation rate in plasma is predictive of its in vivo elimination rate, as this is the case in humans. Nine dogs were anesthetized with pentobarbital and administered different bolus doses of cisatracurium in a randomized cross-over design. Arterial blood was collected at frequent intervals after each bolus injection. In vitro degradation rate ( k _{in vitro} ) of cisatracurium was determined in each dog blank plasma. Plasma concentrations were determined by HPLC. Pharmacokinetic analyses were performed using two compartmental models assuming central or both central and peripheral elimination. Mean in vivo terminal elimination rate of cisatracurium (16.4 ± 2.7 min) was twofold faster than mean in vitro degradation rate (32.9 ± 3.7 min) in our dogs. Organ clearance was 6.12 ± 1.69 mL/min·kg and accounted for 56 ± 12% of the total body clearance. Apparent volume of distribution, an exit site-dependent parameter, averaged 212 or 184 mL/kg whether or not peripheral elimination was accounted for in the model. The in vitro rate of degradation in plasma is not of predictive value for the in vivo elimination rate of cisatracurium in anesthetized dogs. Organ clearance plays a more important role in the elimination of cisatracurium in dogs than in humans. Increased biliary excretion and/or presence of renal secretion are potential mechanisms that need to be explored.     

Endogenous uric acid and urea metabolism in the chicken

1. Four chickens were used in nine successive experiments using a single injection radioisotope dilution technique to study the kinetics of endogenous uric acid and urea metabolism. 2. Starvation lowered uric acid and urea entry rates, but elevated the extent of degradation of these compounds. 3. Urea turnover time and the extent of urea pool degradation were higher, and urea excretion rate was lower than that of uric acid. 4. In colostomised chickens, the extent of uric acid and urea degradation were lower than in non-colostomised birds. 5. The average uric acid and urea entry rates in chickens fed on a diet containing 200 g protein/kg were 7.32 and 2.6 mumol/h g liver, respectively. 6. It is concluded that the contribution of uric acid and urea to the nitrogen economy of the birds is negligible.     

An investigation of carbohydrate and protein degradation ratios,nitrogen to energy synchronization and hourly effective rumen digestion of barley: effect of variety and growth year

The objective of this study was to investigate rumen available soluble, insoluble and total protein (CP), estimated structural (SC) and non‐structural carbohydrate (starch: ST), degradation characteristic ratios and hourly effective degradation of six barley varieties during three consecutive growth years (2003, 2004, 2005). The magnitude of the differences was determined between the varieties and growth years. Measured degradation kinetics included soluble fraction (S), undegradable fraction (U), lag time (T₀) and rate of degradation (K_d) of the insoluble but degradable fraction (D). Rumen available soluble, insoluble, and total N, SC and ST and the rumen degradation characteristic ratios were determined using the Tamminga rumen degradation ratio system. Characteristics of the hourly effective degradation between N and carbohydrate (CHO) among the six barley varieties for 3 years were also studied. The degradation ratios included were total rumen available N and carbohydrate ratio (FN/FCHO), rumen available soluble N and carbohydrate ratio (SN/SCHO), and rumen available insoluble N and carbohydrate ratio (EN/ECHO). Results show that both the barley variety and growth year had a significant effect on degradation kinetics (S, D, U, T₀ and/or K_d). Differences in the ratio of FN/FCHO among varieties ranged from 16.6 to 19.0 g/kg (p < 0.01). There was no difference in SN/SCHO (p > 0.05) with an average of 4.9 g/kg. The difference in the EN/ECHO ratio tended to be significant among the varieties (p = 0.069) ranging from 18.4 to 21.3 g/kg. Differences in the hourly effective degradation between N and CHO were relatively small at shorter incubation times (2–4 h) However, as the length of rumen incubation increased (12–24 h), much larger differences in the rate of effective hourly degradation were observed. In conclusion, both barley variety and growth year had significant effects on rumen degradation kinetics. The mean FN/FCHO ratio of 17.2 (16.6–19.0) was observed for the six barley varieties in this experiment. All barley varieties exhibited a less optimal rumen fermentation ratio (17.2 < optimum: FN/FCHO = 25 to 33 g N per kg CHO). The large differences in the degradation kinetics, characteristics ratios and hourly effective degradation among barley varieties and growth years may help to explain some of the large variations that are seen in cattle performance.     

A flow-limited simulation model of isotopic water dilution

A model of the kinetics of water metabolism is not synonymous with an anatomic model of body water pools. Quantitating the anatomic relations of pools of body water that are separable on a kinetic basis is very difficult, and these relations are influenced by the physiological state of the animal. A fifteen-pool, flow-limited simulation model of body water distribution and mixing was constructed based on literature values to study the relationship between anatomical and kinetic pools of body water. The blood dilution curve predicted by the model agrees well with dilution curves in the literature. Altering rumen water volume in the model does not alter the blood dilution curve. Segmenting anatomical pools of water on the basis of blood deuterium oxide (D2O) dilution curves is not a realistic goal. Total body water, independent of the physiological state of the animal, can be measured by D2O dilution after isotopic equilibration has been established if corrections are made for the amount of D2O that is lost prior to attaining equilibrium. The model can be used to search for dosing and sampling schemes that have the potential for fractionating anatomical pools of body water. Although the model is not predictive of any particular situation, it does provide a good base for researching kinetics of body water distribution and body composition.     

Apparent ruminal degradation and rumen escape of soluble nitrogen fractions in grass and grass silage administered intraruminally to lactating dairy cows

The main objective of this study was to investigate in vivo ruminal degradation and rumen escape of soluble N fractions in grass and grass silage. Soluble protein and long-chain peptides (PLP), small peptides (SP) and free AA (FAA) were obtained from fresh grass and grass silages fertilized with different levels of N. Soluble extracts from the forages were pulse dosed into the rumen of three cannulated lactating dairy cows, and a simple or complex model was used to examine the kinetics of the soluble N fractions in the rumen. When soluble extracts from silage were investigated, pulse dosages of total nonammonia N (NAN) were 21, 27, and 32 g, while for fresh grass only dosages of 20 g were ruminally administered. In the silage extracts, mean proportions of PLP-N, SP-N, and FAA-N in the NAN were 30, 52, and 18%, respectively, whereas in the fresh grass the corresponding values were 67, 20, and 13%. From silage extracts, all three soluble N fractions showed a linear decrease (P < 0.05) in degradation rate and an increase (P < 0.05) in ruminal escape with increasing dosage. In silage, mean degradation rates, parameterized from the complex model, were 230, 214, and 334%/h for PLP-N, SP-N, and FAA-N, respectively, and the ruminal escape was highest (P < 0.05) for SP-N (11.2% of dose) and lowest (P < 0.05) for FAA-N (5.0% of dose). No differences in degradation rate and ruminal escape between fresh grass and silage were observed. However, the proportion of N dose converted to ammonia was only 24% in the fresh grass, whereas for the silages a mean value of 76% was found. From this study, it is concluded that a significant amount of dietary soluble N escapes ruminal degradation, and thus contributes to the intestinal AA supply. Moreover, if the main aim is to study degradation kinetics of individual N fractions, a complex model should be used in the evaluation. This model can also be used to study ruminal synchronization of N and energy for microbial growth.     

Pharmacokinetics of phenobarbital in the cat following multiple oral administration.

Phenobarbital was administered orally to seven healthy cats at a dose of 5 mg/kg once a day for 21 days. Serum phenobarbital concentrations were determined using a commercial immunoassay technique. A one-compartment model was used to describe the final elimination curve. The elimination half-life (t1/2 b) after the final day of treatment was 43.3 +/- 2.92 h. The large apparent volume of distribution of 695.0 +/- 43.9 mL/kg suggests that the drug was widely distributed within the body. The t1/2 b following multiple oral administration was significantly shorter than previously reported for a single oral dose of phenobarbital in the cat. Analysis of pharmacokinetic results after days 1 and 21 of treatment suggested that the elimination kinetics of phenobarbital did not change significantly with multiple oral administration. It appears that differences in elimination kinetics can exist between populations of cats. These differences emphasize the need for individual monitoring of cats receiving phenobarbital.     

Pharmacokinetic aspects of a sulphachloropyridazine trimethoprim preparation in normal and diseased fowl

1. The pharmacokinetic and residue elimination patterns of sulphachloropyridazine appear to be modified by disease, even without affecting key organs essential for drug metabolism. 2. Drug kinetics and residue elimination data of a sulphachloropyridazine-trimethoprim preparation were compared using infectious coryza-affected (IC) fowl and healthy chickens. 3. The plasma concentrations of sulphachloropyridazine and trimethoprim were higher in affected animals, hence a reduced volume of distribution was obtained. 4. The half-life of sulphachloropyridazine and trimethoprim was reduced in IC-affected fowl and body clearance values were decreased. 5. The rate of drug residue elimination was noticeably slower in the IC-affected group. 6. These results indicate that drug elimination patterns in healthy and diseased animals are not the same.     

Protein kinetics in callipyge lambs

The objectives for this experiment were to determine the effect of the callipyge phenotype on protein kinetics. We studied callipyge and normal lambs (n = 37) at 5, 8, and 11 wk of age (n = 4 to 7/ group) to determine how protein kinetics are altered by this trait. Total protein, DNA, and RNA and calpastatin activity were measured in five skeletal muscles and in the heart, kidneys, and liver, and protein accretion rates were calculated. At 8 wk, the fractional synthesis rates of proteins in these tissues were measured in vivo using a primed, continuous 8-h infusion of [2H5]phenylalanine. Fractional rates of protein degradation were estimated by differences. At 5 wk of age, muscle weights, protein mass, protein:DNA, RNA:DNA, and calpastatin activity were higher (P < .05) for callipyge, and protein mass differences continued to increase through 11 wk. At 8 wk, fractional rates of protein synthesis and degradation were lower (P < .05) in callipyge than in normal lambs. The organs of callipyge lambs exhibited reduced growth at 11 wk. Thus, enhanced muscle growth seems to be maintained in callipyge lambs by reduced protein degradation rather than increased protein synthesis. However, we cannot exclude the possibility that the initial onset of the callipyge condition may be caused by an increase in the fractional rate of protein synthesis.     

Effect of herbage depletion on short-term foraging dynamics and diet quality of steers grazing wheat pastures

Two complementary experiments were completed to assess short-term foraging dynamics, diet quality, and ruminal degradation kinetics of herbage consumed by steers with 3 levels of herbage depletion. Experiment 1 was a behavioral study in which 2 ruminally cannulated steers were allocated to grazing scenarios simulating 3 levels of herbage depletion. These treatments included an ungrazed sward (control), as well as medium and high levels of herbage depletion. Grazing scenarios were sampled for sward surface height and amount of green leaf and stem before being grazed. Foraging dynamics were determined through measurements of bite rate, bite depth, eating step rate, eating distance, potential area consumed while grazing, and bites and intake per eating step. Also, quality of potential herbage consumed was estimated from hand-plucked herbage. In Exp. 2, ruminal degradation kinetics of DM for samples of herbage consumed (masticate) by steers during Exp. 1 were assessed in situ using 5 ruminally cannulated steers. The immediately soluble, degraded, and undegraded DM fractions were determined. The DM disappearance rate and lag times were determined from a nonlinear regression model, and the effective degradability of DM was calculated. Herbage depletion resulted in increased eating steps/minute, as well as the potential area harvested while grazing (P < 0.05) and reduced herbage intake/eating step (P < 0.05). Neither the herbage potentially consumed nor the ruminal degradation kinetics was affected by extent of depletion (P > 0.05). Under these experimental conditions, steers adapted their foraging dynamic and were able to sustain diet quality in the short term. These results imply that behavioral adaptations would make diet quality less sensitive to certain levels of herbage depletion.     

Drug residues in food animals. III. Plasma and tissue kinetics of potassium penicillin G in young cross-bred swine

Twenty-two young cross-bred swine were treated either intravenously or orally with potassium penicillin G. The pharmacokinetics of penicillin G were determined in plasma and tissues. The plasma half-life of penicillin G in swine was found to be 19.45±1.69 min, and the distribution and elimination kinetics were found to fit a classical two-compartment model. The volume of distribution was found to be 0.53±0.12 1/kg, and the body clearance was found to be 19.06±5.06 ml/min/kg which exceeded the effective renal plasma flow of 16.50±2.73 ml/min/kg, suggesting that the drug was eliminated both by tubular excretion and glomerular filtration. The elimination rate constants (Beta) for the major organs were as follows: muscle, 0.00343 min^-1; lung, 0.0310 min^-1; fat, 0.0394 min^-1; and kidney, 0.0213 min^-1, which compared favorably with the elimination rate constant found in plasma (0.0320 min^-1). These values were found to be significantly similar at the level of P < 0.005 in muscle, spleen and fat, and at a level of P < 0.025 in lung tissue. The data indicates that blood plasma would be a satisfactory body fluid for estimating this drug in tissue.