饲粮类型和肥育后期不添加维生素和微量矿物元素对猪生长性能、胴体和肌肉品质、粪中矿物元素排泄的影响

本研究共开展两个试验,探讨饲粮类型和不添加维生素和微量矿物元素对猪肥育后期生长性能、胴体和肌肉品质、粪中微量矿物元素排泄的影响。在试验1中,选用128头平均体重(78.5±4.6)kg的肥育猪,根据体重和性别分成4组,每组4圈(重复),每个重复8头猪。四组试验猪的试验处理为2×2因子设计,即两种类型(玉米-豆粕型和玉米-杂粕型)饲粮和添加或不添加维生素/微量矿物元素预混料。在试验2中,选用112头平均体重(90.3±6.3)kg的肥育猪,根据体重和性别分成4组,每组4圈(重复),每个重复7头猪。试验处理同试验1。结果显示,在79~110kg肥育期中(试验1),采食玉米-豆粕型饲粮的猪的增重速度和采食量显著高于采食玉米-杂粕型饲粮的猪(P<0.01或0.05)。在90~105kg肥育期中(试验2),采食玉米-豆粕型饲粮的猪的增重速度仍然高于采食玉米-杂粕型饲粮的猪(P<0.05)。但是,维生素和微量矿物元素添加与否对生长性能无显著影响(P>0.05)。饲粮类型和不添加维生素和微量矿物元素对胴体和肌肉品质均无显著影响(P>0.05)。粪中微量矿物元素含量不受饲粮类型的影响(P>0.05),但不添加维生素和微量矿物元素时,粪中铜、铁、锰的含量显著降低(P<0.01),粪中锌含量也有降低的趋势(P>0.05)。对于生长性能、胴体和肌肉品质以及微量矿物元素排泄量,饲粮类型×维生素/微量矿物元素预混料的交互作用不显著(P>0.05)。结果表明,在猪的肥育后期(最后约25~40d),在玉米-豆粕型和玉米-杂粕型饲粮中可不添加维生素和微量矿物元素,从而可降低饲料成本和减少微量矿物元素的排泄。     

Pharmacokinetics, urinary excretion and dosage regimen of levofloxacin following a single intramuscular administration in cross bred calves

The pharmacokinetics and urinary excretion following single intramuscular administration of levofloxacin at a dose of 4 mg/kg was investigated in seven male cross bred calves. Appreciable plasma concentration of levofloxacin (0.38 ± 0.06 µg/ml) was detected at 1 min after injection and the peak plasma level of 3.07 ± 0.08 µg/ml was observed at 1 h. The drug level above MIC₉₀ in plasma was detected up to 12 h after administration. Rapid absorption of the drug was also evident by the high value of the absorption rate constant (2.14 ± 0.24 /h). The overall systemic bioavailability of levofloxacin, after intramuscular administration, was 56.6 ± 12.4%. The high value of AUC (7.66 ± 0.72 mg . h/ml) reflected the vast area of body covered by drug concentration. Extensive distribution of the drug into various body fluids and tissues was noted by the high value of Vd_area (1.02 ± 0.05 l/kg). The high ratio of AUC/MIC (76.6 ± 7.25) obtained in this study indicated excellent clinical and bacteriological efficacy of levofloxacin in calves. The elimination half-life and MRT were 3.67 ± 0.4 h and 5.57 ± 0.51 h, respectively. The total body clearance (Cl_B) was 204.9 ± 22.6 ml/kg/h. On the basis of the pharmacokinetic parameters, a suitable intramuscular dosage regimen for levofloxacin in calves would be 1.5 mg/kg repeated at 12 h intervals.     

松口蘑的镇咳、祛痰、平喘作用研究

用动物实验方法，研究松口蘑子实体水溶性提取液治疗支气管炎，咳、痰、喘三种症状的效果及其药理作用。给豚鼠腹腔注射松口蘑子实体水溶性提取液，能非常显著地增大方波刺激迷走神经的引咳阈值；给小白鼠灌胃。能非常显著增加其呼吸道的酚红排泌量；给豚鼠离体气管滴入提取液，对气管有非常显著的扩张效应；该提取液能非常显著地延长豚鼠的引喘潜伏期，对蛙口腔粘膜上皮的纤毛运动有一定的加快作用。松口蘑子实体水溶性提取液有明显的镇咳、祛痰和平喘作用。     

Behaviour modifying effects of low systemic concentrations of imidacloprid on Myzus persicae with special reference to an antifeeding response

With a combination of biological, analytical, electrophysiological, and video-optical methods, it was possible to show that low concentrations of the new chloronicotinyl insecticide, imidacloprid, strongly affect the behaviour of Myzus persicae (Sulz.), leading eventually to the death of the aphids. Tests to elucidate the biological properties were performed under laboratory conditions with cabbage leaf petioles placed in insecticidal solutions over different periods of time. LC_15(24h) values were considered as low concentrations and calculated for imidacloprid and pirimicarb, respectively. Imidacloprid at low concentrations depressed the honeydew excretion of apterous adults of M. persicae by almost 95% within 24 h without affecting the vitality of the majority of aphids, whereas, at equitoxic concentrations, pirimicarb showed much weaker effects on honeydew excretion, which strongly coincided with mortality. In choice experiments with alate morphs of M. persicae over 48 h, their larvae almost always occurred on the untreated control leaf, and were not found on the leaf which was treated systemically with low concentrations of imidacloprid. Apterous aphids placed on cabbage leaves systemically treated with low concentrations of imidacloprid showed nearly the same decrease in weight as untreated starving aphids, suggesting that their death was caused by starvation. Aphids that were moved from imidacloprid-treated to untreated leaves after 24 h began feeding on the latter and showed a steady increase in weight and honeydew production. This suggests that the behavioural response is reversible. Aphids on pirimicarb-treated (equitoxic dose) leaves showed no decrease in weight. Electrical penetration graphs revealed that M. persicae on artificial membranes containing imidacloprid probed more often before feeding than aphids on control sachets. Time-lapse videofilming of apterous adults placed on cabbage leaves revealed a migration from the leaf treated with low concentrations of imidacloprid to an untreated leaf. From the results of these experiments and the observed symptomatology it is possible to postulate two different and dose-dependent modes of action of imidacloprid on M. persicae: (1) the well-known mode of action with visually obvious irreversible symptoms (paralysis, tremor, uncoordinated leg-movement) at field rates, and (2) the reversible starvation response as an antifeedant effect, which is not coupled with typical symptoms of neuronal disorder, at lower concentrations.     

Effect of dietary phosphorus content on milk production and phosphorus excretion in dairy cows

Background

Phosphorus (P) supplementation is costly and can result in excess P excretion. This study investigated the effects of reducing dietary P on milk production and P excretion in dairy cows over a full lactation.

Method

Forty-five multiparous Holstein dairy cows were divided into 15 blocks according to expected calving date and previous milk yield, and assigned randomly to one of the three dietary treatments: 0.37, 0.47, and 0.57% P (DM basis); these P levels represent the NRC recommendations, Chinese recommendations, and the amount of dietary P commonly fed by Chinese dairy farmers, respectively. Average daily feed intake was calculated from monthly data on feed offered and refused. Milk yields of individual cows were recorded weekly, and milk samples were taken for analysis of protein, fat, solids-not-fat, lactose, and somatic cell count. Blood samples were collected on days −6, −3, 0, 3, 6 relative to calving, and then monthly throughout lactation, and analyzed for P and Ca concentrations. Spot samples of feces and urine were collected for 3 consecutive d during weeks 12, 24, and 36, and P concentrations were analyzed. Reproduction and health data were recorded.

Results

Dietary P did not affect dry matter intake or milk yield (P > 0.10). Milk fat content was slightly higher in cows fed 0.37% P than in cows fed 0.47% P (P = 0.05). Serum concentrations of P and Ca did not reflect dietary P content (P > 0.10). Fecal and urinary P both declined linearly (P < 0.05) as dietary P decreased from 0.57 to 0.37%. Fecal P content was 25% less when dietary P was 0.37% compared to 0.57%. Health events and reproductive performance were not associated with dietary P content (P > 0.05).

Conclusions

Lowering dietary P from 0.57 to 0.37% did not negatively affect milk production, but did significantly reduce P excretion into environment.     

The Disposition Kinetics,Urinary Excretion and Dosage Regimen of Ciprofloxacin in Buffalo Calves (Bubalus bubalis)

The disposition kinetics, urinary excretion and a dosage regimen for ciprofloxacin after a single intravenous administration of 5 mg/kg was investigated in 5 healthy buffalo calves. The disposition kinetics were best fitted to a three-compartment open model. After 1 min, the concentration of ciprofloxacin in plasma was 8.50±0.39 g/ml and the minimum therapeutic concentration was maintained for 10 h. The elimination half-life and volume of distribution were 3.88 and 0.08 h and 3.97±0.22 L/kg, respectively. The total body clearance and T/P ratio were 0.709±0.025 L/kg per h and 6.13±0.54, respectively. Approximately 28.3% of the total administered dose of ciprofloxacin was recovered in urine within 24 h of administration. To maintain a minimum therapeutic plasma concentration of 0.10 g/ml, a satisfactory intravenous dosage regimen of ciprofloxacin, computed on the basis of disposition kinetic data obtained in healthy buffalo calves, would be 3 mg/kg repeated at 12 h intervals.     

Earthworm contributions to soil nitrogen supply in corn-soybean agroecosystems in Quebec, Canada

Accurately quantifying the soil nitrogen(N) supply in crop fields is essential for enabling environmentally sustainable and economically profitable crop production. It requires using field-based methods to account for the contribution of soil biota, including earthworms, to N mineralization in temperate agroecosystems. The direct contribution of earthworms to the soil N cycle is the N they release throughout their life and after death, and it can be estimated using the secondary production method. This study was conducted in 2014 and 2015 in two adjacent fields with annual corn-soybean rotation in Ste-Anne-de-Bellevue, Quebec, Canada. The cumulative biomass of Aporrectodea spp. in two no-till corn-soybean agroecosystems was determined, and the direct N flux from these earthworms was estimated during the corn and soybean phases of the rotation. Secondary production was estimated by sampling earthworms biweekly during April–June and September–November and inferring the change in earthworm biomass between sampling dates using a size frequency calculation. The N flux was calculated as the sum of the N released through excretion, during periods when earthworms were active, and from mortality. The secondary production of the Aporrectodea population was estimated to be 8–43 g ash-free dry weight m~(-2) year~(-1), and the N flux was 22–105 kg N ha~(-1) year~(-1). The N flux was higher at the early vegetative growth stage, which is a period of high N demand for corn. These findings suggest that refining the N fertilization recommendation by accounting for soil N supplied by earthworms could potentially reduce fertilizer costs and environmental N losses.     

异生物素及其代谢物在反刍家畜体组织的分泌与排泄机理

胆汁分泌和尿液排泄是异生物素如芳香族和脂环族化合物排出反刍动物有机体的主要途径.渗透过滤是胆汁分泌的主要机制,离子运输对共轭态异生物素的胆汁分泌具有重要作用,其影响因素主要为代谢物极性、分子量和结构.胆汁分泌促进了异生物素在动物体内持续地进行肠肝循环.肾脏中的分泌排泄过程在肾单位中进行.代谢物的尿液排泄包括3个基本过程:肾小球过滤、肾小管分泌和肾小管再吸收.家畜有机体排出异生物素的其他途径有唾液、乳汁、汗水和气体.家畜对某一特定饲料的采食量以及饲料本身的属性直接影响异生物素经尿液的排泄,以此建立合理的关系模型就可以根据尿液中的排泄量测定或预测家畜的采食量.     

Oxygen consumption and ammonia excretion of the freshwater crab Trichodactylus borellianus exposed to chlorpyrifos and endosulfan insecticides

The effects of lethal and sublethal concentrations of chlorpyrifos and endosulfan on oxygen consumption and ammonia excretion rate of the crab Trichodactylus borellianus were evaluated. Oxygen consumption and energy expenditure had significant effect in relation to exposure times. Regarding endosulfan, a significant difference in consumption among times of exposure was registered in 625 μg L⁻¹. Moreover, at the highest concentration, energy expenditure rate was observed stabilized during 1-3 h. A significant increase in ammonia excretion was evidenced in 150 and 300 μg L⁻¹ of chlorpyrifos. The O:N ratio showed a decrease in chlorpyrifos and in 2500 μg L⁻¹ of endosulfan. This indicated a shift towards protein primary metabolism. An increment in the O:N ratio was observed in the lower endosulfan solutions. The relation oxygen:nitrogen showed a shift towards lipid and carbohydrate primary metabolism. This work indicated the complexity of the metabolism in the freshwater crab affected by xenobiotic elements.     

乳尿素氮估测奶牛尿氮排泄量的两个模型比较研究

比较了乳尿素氮估测奶牛尿氮排泄量的两个模型(模型1,UN=17.64×MUN;模型2,UN=10.068×MUN+47.29)的差异显著性,并利用24篇有关文献中泌乳奶牛乳尿素氮含量和尿氮排泄量的数据进行了残差图分析,评价了上述两个模型的准确性情况。结果表明,两个模型存在极显著差异(P0.01),且均不能准确估计奶牛的尿氮排泄量。