Intoxication Induced by Urea Containing Diets in Broiler Chickens: Effect on Weight Gain, Feed Conversion Ratio, Hematological and Biochemical Profiles

Urea as a source of cheap non-protein nitrogen is used to adulterate fish and meat meals which are basic components of broiler diets. The present study was carried out to elucidate the effects of urea on weight gain, and hematological and biochemical profiles. A total of 48 broiler chicks were randomly allotted into 4 groups, designated Groups 1, 2, 3 and 4 of 12 birds each. Birds in Groups 2, 3 and 4 were fed on diets containing urea at the levels of 1%, 2.5% and 4%, respectively. Birds in Group 1 served as control and were not exposed to urea. Experimentation period was for 3 weeks and experiment was terminated when birds were 42 days of age. Body weight of all intoxicated birds at the various intervals was significantly decreased in comparison with that of the untreated control. Compared with control, all intoxicated broilers manifested significant (P ≤ 0.05) decrease in all hematological parameters involving erythrocytic and total leucocytic counts, Hemoglobin (Hb) and Packed Cell Volume (PCV) on a dose- and time-pattern. In comparison with the control levels, biochemical profile of the intoxicated birds disclosed significant decrease in blood glucose level and significant increase in serum uric acid, urea, Alkaline Phosphatase (ALP) and Lactate Dehydrogenase (LDH) levels. Based upon the present data, it was concluded that the addition of urea to broiler diets bears serious sequences concerning the general health condition, performance, weight gain, and hematological and biochemical profiles.

The Effect of Quantitative Feed Restriction Duration on Growth Performance and Carcass Characteristics of Broiler Chickens

The growth productivity of broilers is influenced by improving growth performance through improving body weight, average daily gain, and feed conversion rate. The objective of the study was to determine the effect of quantitative feed restriction duration on growth performance and carcass characteristics of broilers. A total of 144 day-old broiler chicks were reared in a deep litter system until slaughter at 42 days. Chicks were randomly allocated to three treatments which were replicated three times with 16 birds per replicate. The three treatments were the control (T1), one week of feed restriction (T2), and two weeks of feed restriction (T3). Birds were fed with starter, grower and finisher diets. The average daily gain (ADG), average daily feed intake (ADFI), and the feed conversion ratio (FCR) were computed for each week. Carcass weight and internal organs weights were measured. The body weight gained by the birds in T1 was similar to the birds that were restricted for a week. The treatments had a significant effect on the average daily gain in weeks 4, 5, and 6. The ADG for T2 was higher (P < 0.05) at week 5 after 1 week of restriction, than T1 and T3. The feed conversion ratio was significantly higher in T3 after 2 weeks of restriction. In T2 and T3, feed intake was significantly lower than in birds fed ad libitum at week 4 at the start of the treatment. There was no significant effect on the relative weights of heart weights, liver, gizzard, feet, and heads among the treatment groups except for intestine weight which was lower (P < 0.05) in T1 than T2 and T3. It was concluded that broilers that were restricted for one week had a positive result in growth performance. Feed restriction had minimal effect on the organ weights of broiler chickens.

Effects of Feeding Time on the Growth Performance and Variation of RNA/DNA Ratio of the Chinese Soft-shelled Turtle, Pelodiscus sinensis

The present study was to investigate the effects of feeding time on growth of the Chinese soft-shelled turtle. The experiment was carried out with a photoperiod of 12L （light）： 12D （dark） with lights on at 06：00 and off at 18：00. Turtles were maintained at a temperature of 32 - 0.2 ℃ in tanks throughout the length of the experiment. The turtles in group 1 to group 6 were fed respectively at 00：00, 04：00, 08：00, 12：00, 16：00 and 20：00 with 60 turtles each （Initial body weight 88.27 - 0.09 g）. Acrophases of postprandial RNA/DNA ratio in liver in each group was shown between 5h and 7h after feeding. A positive linear correlation could be seen between specific growth rate （SGR） and RNA/ DNA：SGR=t.1586RNA/DNA-0.7097 （r = 0.9328, P = 0.0066）. The results indicated that the values at the acrophases of about 6h after feeding might be used as an instantaneous growth index in the Chinese soft-shelled turtle. The turtles in group 1 grew better than group 3, group 4, group 5, group 6, because they ate more, but they ate more and grew slower than group 2, whose feed conversion rate was also higher. Meanwhile, the SGR and feeding rate of turtles fed at 12：00 were the lowest from the six groups （P 〈 0.05）. Turtles fed in group 1, group 2 and group 6 developed more heavy final body weight （FBW）, higher feeding rate and SGR than the other three groups. This probably suggested that turtles fed in scotophase grew better than that fed at photophase in total.

基于工程应用的CW-GMAW熔滴过渡形态表征

综述了涉及工程应用的冷丝熔化极气体保护焊(Cold wire gas metal arc welding,CW-GMAW)熔滴过渡形态特征。结果表明,在大电流、强规范、富氩混合气体保护下,CW-GMAW工艺的熔滴过渡形态呈喷射过渡;当电流较小、电弧电压较低时,可能为滴状过渡,甚至在弧压很低时,呈现短路过渡形态。该工艺电弧发生偏向冷丝的位移,弧长变短甚至发生短路,与冷丝送进速率比增高及冷丝在电弧中产生大量金属蒸气时弧柱电阻下降有关。在具有富氩混合保护气体的相同工艺参数下,CWGMAW转变电流比GMAW降低了4%~7%。焊接工艺参数对CW-GMAW和GMAW工艺熔滴过渡形态的影响规律大致相近,但前者因涉及冷丝送进速率比和电极焊丝送进速度,以及它们的匹配等,使焊接电流的影响更为复杂。

补料比及反冲推头倾角对Y型管内高压成形质量的影响研究

目的解决5A02铝合金Y型管在内高压成形过程中易出现破裂和内凹缺陷的问题,以获得最佳成形质量的管件,对成形中的补料比和反冲推头倾角进行研究。方法使用内高压成形机进行实验,分析了管件的表面质量、管件壁厚分布情况,研究了补料比和反冲推头倾角对Y型管成形质量的影响。选取端面倾角大小分别为0°、13.5°、27°的反冲推头进行实验,设计了1.5∶1、2∶1、2.5∶1和3∶14组补料比进行对比分析。结果比较3种不同反冲推头成形得到的管件,通过对支管成形效果的分析,确定13.5°为最佳反冲推头倾角;补料比在1.5~2.5时可成形出Y型管,补料比为2∶1时,Y型管成形质量最好。为获得成形质量高的Y型管,需选择补料比为2∶1的加载路径和端面倾角为13.5°的反冲推头进行实验。结论采用合适的反冲推头端面倾角,既可以使Y型管获得理想高度的支管,又可有效地抑制成形中期支管出现的破裂缺陷;选择合理的补料比可以避免过渡圆角内凹缺陷,也可以改善Y型管的壁厚分布情况,进一步提升管件最终的成形质量。

聚合条件对聚羧酸减水剂缓释行为的影响

以乙二醇单乙烯基聚乙二醇醚(EPEG)、丙烯酸(AA)、丙烯酸羟乙酯(HEA)为主要合成原料,以3-巯基丙酸为链转移剂,在双氧水/抗坏血酸氧化还原体系下,利用自由基聚合法合成缓释型聚羧酸减水剂,并系统研究了原料配比和溶剂反应条件对聚羧酸减水剂缓释行为的影响。利用傅里叶红外光谱(FT-IR)、核磁共振氢谱(1H NMR)和凝胶渗透色谱(GPC)等对减水剂分子结构进行表征,对掺入不同减水剂的水泥净浆和砂浆进行性能测试。研究表明:在酸醚体积比为3∶1、醇水体积比为1∶2、酸酯体积比为3∶1时,合成的缓释型聚羧酸减水剂具备最佳性能,水泥浆体初始流动度大且具有良好的缓释效果。

基于竞聚率设计制备组成均匀的聚羧酸减水剂

基于实验得到的聚羧酸减水剂(PCE)共聚单体的竞聚率数据,采用控制转化率和补加活泼单体相结合的方法,结合理论计算和实际测定结果,确定了活泼单体丙烯酸(AA)补加时间及补加量,使其在共聚过程中始终与大单体异丁烯基聚乙二醇醚(MAPEG)组成保持基本不变,以保证聚合反应不同时间段生成的共聚物组成和结构与设计值一致。为系统研究控制工艺的准确性和可靠性,将其与传统投料工艺反应过程中所得产物的组成对比,考察了控制共聚物组成对分散性能的影响。结果表明,基于竞聚率的控制工艺制备PCE过程中,分段补加消耗较快的AA抑制了AA和MAPEG在共聚物瞬时组成的变化幅度,共聚物的平均酸醚比[n(AA)/n(MAPEG)]分别为2.8、3.8、4.8,基本接近设计酸醚比(3.0、4.0、5.0);其制备的PCE平均主链长度及主链上羧基含量、大单体含量较高,使PCE覆盖面积和吸附层厚度增大,从而提升了水泥净浆初始流动度和流动保持性能。

内环化聚(β-氨基酯)的制备与生物物理性能

拓扑结构对聚合物性能具有重要影响.本文通过调控聚合条件制备内环化聚(β-氨基酯)并探究其生物物理性能.以三羟甲基丙烷三丙烯酸酯(TMPTA)和4-吗啉丙胺(MPA)为单体并控制其投料比及体系单体浓度,利用迈克尔加成反应制备了两种内环化聚(β-氨基酯).使用凝胶渗透色谱仪(GPC)、核磁共振波谱仪(NMR)和原子力显微镜(AFM)等对内环化聚(β-氨基酯)的化学组成、拓扑结构和生物物理性能进行表征与分析.结果表明,随着环化度的增加,聚(β-氨基酯)对DNA压缩能力增强,降解速率加快,质子缓冲能力提高,细胞毒性增大.本文研究结果为制备和表征内环化聚(β-氨基酯)提供了新思路,也为设计有效的基因递送载体提供了依据.

腐霉利的合成及密度泛函理论研究

我们以3,5-二氯苯胺、1,2-二甲基环丙烷-1,2-二甲酸甲酯(以下简称二甲酯)为原料制备得到了腐霉利。以降低原料消耗量,减少“三废”排放以及提高经济效益为目标,对腐霉利制备中的投料比、反应温度、溶剂进行了优化,确定了最佳反应条件。当使用水作为溶剂,3,5-二氯苯胺与二甲酯的摩尔比为1∶1,反应温度100℃时,以高收率低消耗得到腐霉利。同时,将密度泛函计算与前线轨道理论相结合,对腐霉利可能的衍生方式进行研究。

不同蛋白水平全价颗粒饲料对育肥公羊育肥效果对比研究

本研究主要探讨不同蛋白水平全价颗粒饲料对育肥公羊育肥效果对比。选择体重20 kg左右公羊共计120只(湖羊、澳湖杂交羊、欧拉羊、湖藏杂交羊、萨湖杂交羊各24只),每一个品种公羊随机平均分为3组,分别饲喂蛋白含量12.96%(LP组)、15.04%(MP组)、17.04%(HP组)的全价颗粒饲料,饲喂105 d,研究体重、养殖效益、体尺相关性等指标。结果显示:湖羊、澳湖、萨湖MP组和HP组羊日增重显著高于LP组(P<0.01),湖藏杂交羊3组间差异不显著(P>0.05),欧拉羊日增重HP组显著高于其他2组(P<0.05),澳湖、萨湖羊增重速度最快,日增重达到300 g以上;湖羊、澳湖、萨湖、湖藏MP组和HP组羊料重比显著低于LP组(P<0.01),欧拉羊3组差异均显著(P>0.05),不同品种羊MP组日养殖效益均优于HP组;湖羊、澳湖、萨湖、湖藏羊体重与各体尺之间呈极显著正相关(P<0.01),欧拉羊体重与体长呈极显著相关(P<0.01),体重与胸围、体长呈显著相关(P<0.05)。

加氢尾油裂解制乙烯的工艺条件优化

为寻找加氢尾油裂解制乙烯的最佳工艺条件,分别考察裂解温度、水油比及进料流速对乙烯收率的影响,结果发现最佳工艺条件:裂解温度为855℃、水油比为0.8、进料流速为194.00 g/h,在最佳工艺条件下乙烯收率可达25.48%。

基于数据驱动的FAST主动反射面调节优化模型

针对500 m口径球面射电望远镜(five-hundred-meter aperture spherical radio telescope,FAST)的主动反射面调节问题,利用旋转抛物面在三维空间中的定义建立了一个对任意天体角度均适用的工作抛物面方程,该方法不同于以往的坐标旋转的方法。利用反射面板重心点作为反射点,将反射接收比定义为能把光线反射到馈源舱被其接收的面板数量与300 m口径工作抛物面下总面板数量的比值。结合主索节点径向伸缩距离、边界平稳过度和邻接距离变化幅度三个约束条件,以接收比最大化作为目标函数,建立了一个工作抛物面优化模型,并利用节点数据和模拟退火算法对其进行求解,得到了工作理想抛物面。选用两组天体角度进行实例分析,结果显示调节后的接收比增大12.82%,并给出了工作主索节点的部分径向调节方案。本研究为FAST对于任意天体角度的变形提供了一种新的建模方法,也对馈源舱反射接收比提出了一种新的计算方式。

熔融沉积成形中扁平椭圆截面挤压宽度模型的分析与实验

目的在熔融沉积成形工艺中,挤压宽度是一个被忽视的核心参数,它不仅直接影响层高、进料速率、扫描速率等工艺参数,还间接影响打印制件的表面粗糙度、力学性能、尺寸精度和构建时间。因此,必须严格控制挤压宽度。方法首先在3D打印挤出原理、黏弹性理论和聚合物流变学理论的基础上,提出了扁平椭圆截面模型。然后将该模型的理论计算结果与实验测量数据进行比较,验证了扁平椭圆模型的准确性,并分析了误差的来源。同时在该模型的基础上,研究了料丝直径公差对挤压宽度的影响、扫描速率与进料速率的匹配范围和最大扫描速率。结果提出了挤压长丝截面的扁平椭圆模型,得到了理论挤压宽度的表达式,并通过实验验证了该截面模型的误差在6%以内,并研究了料丝直径公差对挤压宽度的影响、扫描速率与进料速率的匹配关系,以及PLA材料在不同层高下的最大扫描速率。结论为提高打印制件品质和效率提供了重要参考。

一种无片外电容高电源抑制比LDO设计

低压差线性稳压器(Low Dropout Regulator,LDO)电路要求低输入输出压差和高电源抑制比(Power Supply Rejection Ratio,PSRR)。本文采用前馈纹波消除电路和负电容电路实现了在低输入输出压差(≤0.2 V)条件下分别对无片外电容高电源抑制比LDO的10 KHz以下频段和1 MHz频带内的电源噪声抑制能力进行提升。此外,提出的方案还通过调整第二级误差放大器的增益,实现了级间电源噪声制约,进一步提升了电源抑制比。本文基于SMIC 55 nm工艺对提出的LDO电路进行了设计与仿真。结果表明,设计的LDO在1.8 V输入电压下可以获得稳定的1.6 V输出电压,输入输出压差≤0.2 V,在1MHz以下频段内PSRR均大于75 dB,10~100 KHz频段的积分噪声为15μV_(RMS)。此外,该LDO还实现1.43 mV/V线性调整率,负载调整率为10μV/mA,总体电路消耗静态电流为76μA。

Linkage between the intestinal microbiota and residual feed intake in broiler chickens

Background:Intestinal microbiota plays a key role in nutrient digestion and utilization with a profound impact on feed efficiency of livestock animals.However,the intestinal microbes that are critically involved in feed efficiency remain elusive.Methods:To identify intestinal bacteria associated with residual feed intake(RFI)in chickens,male Cobb broiler chicks were individually housed from day 14 to day 35.Individual RFI values were calculated for 56 chickens.Luminal contents were collected from the ileum,cecum,and cloaca of each animal on day 35.Bacterial DNA was isolated and subjected to 16S rRNA gene sequencing.Intestinal microbiota was classified to the feature level using Deblur and QIIME 2.High and low RFI groups were formed by selecting 15 and 17 chickens with the most extreme RFI values for subsequent LEfSe comparison of the difference in the microbiota.Spearman correlation analysis was further performed to identify correlations between the intestinal microbiota composition and RFI.Results:No significant difference in evenness,richness,and overall diversity of the microbiota in the ileum,cecum,or cloaca was observed between high and low RFI chickens.However,LEfSe analysis revealed a number of bacterial features being differentially enriched in either high or low RFI chickens.Spearman correlation analysis further identified many differentially enriched bacterial features to be significantly correlated with RFI(P<0.05).Importantly,not all short-chain fatty acid(SCFA)producers showed a positive association with RFI.While two novel members of Oscillibacter and Butyricicoccus were more abundant in low-RFI,high-efficiency chickens,several other SCFA producers such as Subdoligranulum variabile and two related Peptostreptococcaceae members were negatively associated with feed efficiency.Moreover,a few closely-related Lachnospiraceae family members showed a positive correlation with feed efficiency,while others of the same family displayed an opposite relationship.Conclusions:Our results highlight the complexity of the intestinal microbiota and a need to differentiate the bacteria to the species,subspecies,and even strain levels in order to reveal their true association with feed efficiency.Identification of RFI-associated bacteria provides important leads to manipulate the intestinal microbiota for improving production efficiency,profitability,and sustainability of poultry production.

Analysis of York Pigs Feeding Behavior Using Stepwise Regression and Principal Component Regression

A statistical analysis was conducted on the feeding behavior of 106 York breeding pigs.Pearson correlation analysis,principal component correlation analysis and multiple stepwise regression equation methods were applied to establish regression equations of the York breeding pigs total feed intake per time and average feed intake per time with corrected fat thickness,feed conversion rate,and corrected daily gain.The results showed that:①there were three peak feed intake periods for the pigs,and the correlation coefficient between the feed intake and the corrected fat thickness of the pigs in the 24 h period was positive or negative,that is,increasing the number of feeding times and the feed intake was not necessarily conducive to the fat thickness accumulation,but the breeding goal of fat thickness could be achieved by controlling the feeding times and feed intake;②the average feed intake of pigs in the 60-90 kg body weight stage was 30%-50%higher than that of the 30-60 kg body weight stage,but the number of feeding times decreased,the peak feeding time was more concentrated,and the feeding duration per time was 3.0 min longer,indicating that as the weight of pigs increased,the feed intake increased significantly;and③the stepwise regression equations and the principal component equations showed that the feeding behavior of York pigs in the 30-90 kg growth stage was not only affected by the feeding time within 24 h,but also by environmental factors such as temperature and humidity.The feeding behavior of York pigs is a complex process of interaction between environmental factors and animal factors.

Optimal Supplement Dosage of Double-Low Rapeseed Meal in Concentrated Feed of Fattening Lambs

[ Objective] To determine the optimal supplement dosage of double-low rapeseed meal in concentrated feed of fattening lambs. [ Method] A total of 120 Tibetan lambs at the age of 50 d were selected and divided randomly into four groups. The lambs in these four groups were fed with diets respectively supplemented the double-low rapeseed meal of 50,100,150 and 200 g/kg. Their diets had the same nutritional levels of energy and protein. The experimental period was 120 d. [ Result] Daily gain, feed conservation ratio and economic benefits were largely increased in the lambs fed with the diets supplemented the double-low rapeseed meal of 150 g/kg （Daily gain, P 〈 0.01 ）. However, the daily gain and feed conservation ratio were largely decreased in the lambs fed with the diets supplemented the double-low rapeseed meal of 200 g/kg. Moreover, serum levels of transaminase and thyroxine were not significantly different between the four groups. [ Conclusion] The optimal supplement dosage of the double-low rapeseed meal is 150 g/kg in fattening lambs.

A novel integrated step-feed biofilm process for the treatment of decentralized domestic wastewater in rural areas of China

For wastewater treatment in rural areas, a novel three-stage step-feed wastewater treatment system, combined with a drop-aeration biofilm process, was tested in the laboratory to investigate its performance in removing suspended solids （SS）, chemical oxygen demand （COD）, NH4＋-N, total nitrogen （TN）, and total phosphorus （TP）. The removal rates of SS, COD and NH4＋-N were 90%, 80%, and 90% in efluent concentrations less than 10 mg/L, 50 mg/L and 8 mg/L, respectively. The TP removal rate was less satisfactory. The C/N ratio in the raw wastewater was often less than 3.5, and the removal efficiency of TN was therefore limited. A carbon-release batch experiment was carried out to measure the feasibility of enhancing denitrification at low influent C/N ratios. The result showed that the C/N could be over 9.0 in the supernatant. Polymerase chain reaction denaturing gradient gel electrophoresis technology was used to reveal the changes in the bacterial community during different stages of the integrated step-feed biofilm process. The results showed that banding patterns and the distribution of dominant bands for the same experimental period in different aerobic zones were similar. Phylogenetic analysis indicated that lanes 10, 11 and 12, which presented three aerobic zones at the same operation period, had the closest phylogenetic relationship among the lanes.

Feeding Effect of Growing-Finishing Pigs under Fine Division of Feeding Stages

In order to study the feeding effect of fine division of feeding stages on the growing-finishing pigs,96 healthy Duroc × Landrace ×Yorkshire hybrid commercial pigs with similar age in days,size,and body weight about 15 kg,half boars and half sows,randomly divided into3 treatments( each treatment repeated 4 times,and each repetition 8 pigs). According to the body weight division standard,three stages,four stages,and five stages of feeding were adopted separately. The daily ration of with different nutrition levels was used,body weight and feed consumption were measured,and effects of different feeding methods on body weight increase,feed utilization,and economic benefits of growing-finishing pigs. The results showed that compared with the three-stage feeding,the body weight of five-stage and four-stage feeding increased by 4. 18%( P < 0. 01) and 2. 41%( P < 0. 05),respectively,and the body weight of five-stage feeding increased by 1. 74%( P < 0. 05) compared with that of four-stage feeding; the daily feed consumption of five-stage and four-stage feeding increased 3. 10%( P < 0. 01) and 1. 70%(P <0. 01),respectively,and the daily feed consumption of five-stage feeding was 1. 37% higher than that of four-stage feeding. The feed cost of five-stage feeding and four-stage feeding increased 3. 32%( P < 0. 01) and 1. 61%( P < 0. 05) separately,and the feed cost of five-stage feeding was 1. 69% higher than that of four-stage feeding( P < 0. 01). The income from average body weight increase of five-stage and fourstage feeding increased by 5. 47%( P < 0. 01) and 3. 59%( P < 0. 01) respectively,and the benefit of average body weight increase of fivestage feeding was 1. 81% higher than that of four-stage feeding( P > 0. 05). The crude protein consumption from average body weight increase of five-stage and four-stage feeding decreased by 2. 28%( P < 0. 01) and 1. 68%( P < 0. 01),respectively; the crude protein consumption from average body weight increase of five-stage feeding was 0. 67% lower than that of four-stage feeding; the feed conversion ratio of five-stage feeding,four-stage feeding,and three-stage feeding was 2. 92,2. 93,and 2. 95 respectively. The results showed that compared with the threestage feeding,the four-stage and five-stage feeding could significantly increase the body weight of the growing-finishing pigs,improve the feed utilization level and improve the economic benefits,and the effect of five-stage feeding was better than the four-stage feeding.

Influence of fish meal quality on growth,feed conversion rate and protein digestibility in shrimp (Penaeus chinensis ) and red seabream (Pagrosomus major)

The effect of fishmeal quality on growth,feed conversion ratio and protein digestibility was studied in a growth experiment with shrimp and red seabream.The shrimp and fish were fed three diets varing in the quality of the fishmeal used in the respective feeds: low quality fish meal,good quality fish meal,and Peru fish meal.The experiment lasted for 2 months.The shrimp and fish fed the feed with good quality fish meal showed significantly better feed conversion ratio,weight gain rate,protein digestibility than the other groups.