新型山药收获机下支撑支架的设计与分析

山药收获机下支撑支架是根据主旋转支撑装置的离地高度和开沟深度设计的,在实际作业过程中,链刀切削阻力、螺旋刀切割阻力、输送机构支撑力、油缸的推拉力最终都由下支撑支架承载,作用力较为复杂,容易发生变形和断裂;且链刀切入土壤产生的振动、链节和链轮齿的啮合会给链传动带来工作的不平稳性和有规律的振动,可能会引起共振。为此,在进行山药收获机工作装置设计时,首先采用有限元方法对下支撑支架进行静力学分析,并在静力学分析的基础之上对其进行预应力模态分析,以评估设计的合理性,对结构进行优化。     

Effects of Dietary Crude Protein Levels on Growth Performance,Digestion and Metabolism,and Serum Biochemical Indexes of Super Merino Lamb

The experiment aimed to find out the effects of dietary crude protein levels on growth performance, digestion and metabolism and serum biochemical indexes of Super Merino lamb after weaning.According to the dietary crude protein level, 64 Super Merino weaned lambs were divided into four groups, which the crude protein levels were 13.25%(group Ⅰ), 14.33%(group Ⅱ), 15.53%(group Ⅲ) and 16.60%(group Ⅳ), respectively.The experiment lasted for 60 days, 30 days for the early stage and 30 days for the later stage;And on the 30th and 60th day, blood samples were collected from one head sheep chosen from each replication, and at the end of the feeding test, 3 lambs were randomly selected from each experiment group for a 15 days digestion and metabolism experiment.The results showed that ADFI and ADG in the early and total trial period were significant differences(P<0.05), ADFI and ADG of group Ⅲ were higher than others.The apparent digestibility of nutrients and ME/DE were not significantly changed(P>0.05).In the detection of serum biochemical indexes, there was no significant difference in the earlier stage(P>0.05);At the end of the test, PK and CK showed significant difference between groups(P<0.05).PK presented a rising trend as the protein level improved, CK of group Ⅰ was higher than other groups.In Super Merino lamb early weaning diet, 15.53% protein level in the diet could significantly improve ADG, the apparent digestibility of nutrients, metabolic energy digestibility.At the end of the test, PK and CK were affected by dietary crude protein level significantly.     

Effects of Complex Nutritional Regulation Additives on Growth Performance,Slaughter Performance and Serum Biochemical Indexes of Grazing Sheep in Cold Season

This experiment was conducted to investigate the effects of complex nutritional regulation additives on growth performance, slaughter performance and serum biochemical indexes of grazing sheep in cold season.A single factor random block design was used and 48 grazing ewes with the average weight (28.01±1.70) kg and 7 months old were randomly divided into 4 groups:Group Ⅰ without supplement;Group Ⅱ with concentrate;Group Ⅲ with concentrate+complex formulation 1 (0.30% malic acid, 0.06% cysteamine, 0.08% saccharicterpenin);Group Ⅳ with concentrate+complex formulation 2 (0.60% malic acid, 0.12% cysteamine, 0.16% saccharicterpenin)with 3 replicates per group and 4 grazing ewes per replicate.The results showed that:①The final weight of group Ⅲ was the highest and higher than group Ⅱ and Ⅳ by 6.26% (P>0.05)、3.69% (P>0.05), respectively.The average daily gain of group Ⅲ was highest, and higher than group Ⅱ and Ⅳ by 26.32% (P<0.01)、5.74% (P>0.05) respectively.②Comparing with group Ⅱ, the slaughter rate of group Ⅲ was increased by 4.68% (P>0.05).Compared with groupⅠ, Ⅱ and Ⅳ, the meat percentage of group Ⅲ was increased 18.46% (P<0.05), 10.97% (P>0.05) and 4.40% (P>0.05), while the net meat weight of carcass in group Ⅲ was increased by 49.74% (P<0.01), 13.22% (P>0.05) and 18.27% (P<0.05), respectively.Compared with groupⅠ, Ⅱ and Ⅳ, the net meat rat of carcass in group Ⅲ was increased 10.42% (P<0.01)、6.00% (P>0.05) and 3.37% (P>0.05), respectively.③There was a rising trend as the order of groupⅠ, Ⅱ, Ⅳ and Ⅲ in serum glucose, Ca, P, HDL, LDL, GPT and IgG, while A/G and TG showed a decreasing trend.Based on the above results, in this trial, supplementing complex nutritional regulation additives had good effects on growth performance, slaughter performance and serum biochemical indexes of grazing sheep in cold season.And supplementing complex formulation group 1 (group Ⅲ) was the best.     

Acute and Sub-chronic Toxicity Test on Rats of a New Kind of Antidiarrheal Chinese Herbal Medicine Compound Preparation for Livestock

In order to understand the security of a new kind of antidiarrheal Chinese herbal medicine compound preparation for livestock,acute and sub-chronic toxicity test were conducted.Acute toxicity test used the largest drug dose method,20 Wistar rats were orally treated with the Chinese medicine compound preparation.In the sub-chronic toxicity test,80 rats were randomly divided into 4 groups with 20 rats in each group and orally given a dose of 3 000,1 500,750 and 0 mg/(kg·BW）of Chinese medicine compound preparation once a day for 30 days.The general clinical status was observed,rats weight were measured and the dose was adjusted every week during the test,after the test measured blood routine index,biochemistry index,and preceded the gross anatomy observation,weighing each major organs and calculated the viscera coefficient,and proceded main viscera histopathological observation between the high dose group and the control group.The acute toxicity results showed that every rat would be alive gavaged with the lethal dose（LD₅₀）of compound preparation larger 5 g/(kg·BW).The sub-chronic toxicity autopsy showed that except heart,lung,and testicles in individual rats appeared mild bleeding in the high dose group,the other dose group organs found no abnormal change.The haematological index showed except mononuclear cell rate（P<0.05),and hematocrit declined significantly（P<0.05）in the high dose group,all the indexes of the other groups were in the normal range,there was no significant difference from the control group.The test suggested the Chinese medicine compound preparation was no toxicity under the condition of this test according to acute toxicity classification standard of exogenous chemicals by WTO,there was no effect on the growth and development of rats in the sub-chronic toxicity test,and there was no chronic toxicity at least 1 500 mg/kg feeding conditions in short-term repeated application.     

Effect of micronized pea seeds (Pisum sativum L.) as a substitute of soybean meal on tissue fatty acid composition and quality of broiler chicken meat

This study aimed to evaluate the effect of micronized pea seeds introduced into feed mixes for broilers on the slaughter yield, blood lipid parameters, content of fatty acids in selected tissues, and meat quality. The studies involved 150 1‐day‐old Ross 308 chicks split into three groups (for 42 days). The feed rations differed in terms of the source of proteins: in the control group (C), it was post‐extraction soybean meal (SBM) 100%; in group I, SBM 50% and micronized peas 50%; and in group II, micronized peas only, 100%. Irradiated pea seeds added to the feed ration for chicks reduced the fattening grade of carcasses (P < 0.05). Additionally, significant improvement of blood lipid indices was recorded. The share of the irradiated pea seeds in feed mixes decreased the share of saturated fatty acids in the muscles and abdominal fat and had a positive effect on the n‐6/n‐3 ratio, hypocholesterolemic / hypercholesterolemic ratio, as well as the atherogenic and thrombogenic indices (P < 0.05).     

土壤压砂保水处理含水率对西瓜生产潜力的影响

以西瓜为试材,针对压砂保墒问题,选择压砂时期和灌溉定额作为研究因素,采用对比试验方法研究了压砂保墒效果及其种植西瓜的生产潜力。结果表明:压砂覆盖能够有效保持土壤水分,上年雨季前压砂与雨季后压砂相比较,播种初期前者处理土壤质量含水率可达10.8%以上,而后者仅为8.9%;补水条件下前者比后者处理西瓜纵径大2.8cm,西瓜横径大3.1cm,未补水条件下前者比后者处理西瓜纵径大3.9cm,西瓜横径大2.7cm;补水条件下,前者处理西瓜产量为12 301.0kg·hm~(-2),后者处理西瓜产量为7 549.1kg·hm~(-2),未补水条件下,前者处理西瓜产量为6 723.3kg·hm~(~(-2)),后者处理西瓜产量为3 829.5kg·hm~(-2),可见,压砂保水能够明显提高西瓜生产潜力。     

基于叶绿体ndhA基因内含子序列的DNA条形码在秋海棠属物种鉴定中的应用

以18种秋海棠属植物为试材,基于叶绿体ndhA基因内含子片段,利用Codon Code Aligner软件拼接序列后,通过MEGA软件进行比对并计算19个秋海棠属植物种间及种内遗传距离,最后利用邻接法构建分子系统树,研究了该片段作为DNA条形码对秋海棠属植物进行物种鉴定的可行性。结果表明:秋海棠属19个种类共59个个体的ndhA基因内含子序列长度为1 182bp,在所考察的候选秋海棠属植物中具有最大的种间变异和较小的种内变异,且二者存在极显著差异。在系统树中,秋海棠属植物每一物种能够分别形成各自独立的分支,表现出良好单系性。基于ndhA基因内含子的DNA条形码在识别秋海棠属植物物种方面和传统形态学基本一致。该研究表明,以ndhA基因内含子作为秋海棠属植物DNA条形码进行物种鉴定具有一定的可行性。     

Comparison of a commercial ELISA with the modified agglutination test for the detection of Toxoplasma gondii infection in naturally exposed sheep

Surprisingly few commercial ELISAs are available for the detection of Toxoplasma gondii infection in animals, and none for use in sheep have been evaluated. We thus compared the Bommeli Diagnostics ELISA Toxotest for the detection of T. gondii antibodies in ruminants with the reference modified agglutination test (MAT) in a series of 180 sheep sera. ELISA results were analysed at two cut-off levels (30%, comprising both weakly positive and positive results, and 100%, comprising only positive results), and compared with MAT at three cut-off levels (titre of 1 : 25, 1 : 50 and 1 : 100). The results showed a moderate agreement of ELISA at both cut-offs (kappa = 0.46 and 0.51) with MAT at a cut-off titre of 1 : 100. However, the specificity and positive predictive value were above 95% only at an ELISA cut-off of 100%, indicating its potential as a diagnostic test, particularly in areas with a high prevalence of infection. On the other hand, lower sensitivity and negative predictive value limit its value as a screening test. Thus, the ELISA Toxotest may be used for quick diagnosis of T. gondii infection in sheep in the field, i.e. for the differential diagnosis of ovine abortion storms.     

Anti-oxidative/oxidative status of rat liver after ovariectomy

The lack of protective action of oestrogens which appears during menopausal period may be the reason of serious metabolic disturbances including oxidative stress. The hypothesis was stated that ovariectomy may induce the variations of antioxidant/oxidant status which can be detected in rat liver. A total of 102 healthy Wistar female rats were included in the experiment and divided into control (CON; n = 6), sham-operated (SHO; n = 48) and ovariectomized (OVX; n = 48) groups. Animals from SHO (n = 6) and OVX (n = 6) groups were killed every week during 8 weeks of experiment to detect dynamic changes in examined parameters. Anti-oxidative enzyme activities [glutathione peroxidase (GSH-Px); superoxide dismutase (SOD)] as well as total antioxidant capacity (TAC) and the intensity of lipid peroxidation, measured by the concentration of N,N,diethyl-p-phenylene diamine (DEPPD) radical, were determined in liver homogenates by the use of spectrophotometric methods. Wave-like patterns of examined parameters within 8 weeks of experiment were detected. GSH-Px activity tended to be higher in OVX animals and was significantly lower at 8th week when compared with 1st week of experiment. SOD activity was higher in SHO animals and showed significant differences between 3rd, 4th, 7th and 1st week. TAC values were significantly higher in OVX when compared with SHO groups in 2nd, 4th, 5th week and significantly lower in 3rd, 6th and 7th week of the experiment. The concentration of DEPPD radicals tended to increase in OVX group. In conclusion, ovariectomy which leads to oestrogen insufficiency is reflected as well in variation of anti-oxidative/oxidative parameters in rat liver homogenates.