Effects of dietary forage to concentrate ratio and wildrye length on nutrient intake,digestibility, plasma metabolites,ruminal fermentation and fecal microflora of male Chinese Holstein calves

Twenty-eight male, weaned Chinese Holstein calves((156.8±33.4) kg) were used to investigate the effects of dietary forage to concentrate ratio(F:C) and forage length on nutrient digestibility, plasma metabolites, ruminal fermentation, and fecal microflora. Animals were randomly allocated to four treatments in a 2×2 factorial arrangement: whole-length forage(WL) with low F:C(50:50); WL with high F:C(65:35); short-length forage(SL) with high F:C(65:35); and SL with low F:C(50:50). Chinese wildrye was used as the only forage source in this trial. The grass in the SL treatments was chopped using a chaff cutter to achieve small particle size(~50% particles 19 mm). Dry matter intake(DMI) and organic matter(OM) intake was increased by increasing both F:C(P0.01) and forage length(FL)(P0.05), while acid detergent fiber(ADF) and neutral detergent fiber(NDF) intakes were only increased by increasing the F:C(P0.01). The digestibility of NDF was increased as the FL increased(P0.01), and it was also affected by interaction between F:C and FL(P0.05). Cholesterol(CHO)(P0.01), leptin(LP)(P0.05), and growth hormone(GH)(P0.01) concentrations in plasma were increased as dietary F:C increased. A significant increase in plasma triglyceride(TG)(P0.01), insulin(INS)(P0.05), and GH(P0.01) levels was observed with decreasing dietary FL. Ruminal p H values of calves fed with low F:C diets were significantly lower than those in high F:C treatment(P0.05). Increasing the F:C enhanced ruminal acetic acid(P0.05) and acetic acid/propionic acid(P0.01). Fecal Lactobacillus content was significantly higher, while Escherichia coli and Salmonella contents were significantly lower in WL and high F:C groups(P0.05). Lower fecal scores(higher diarrhea rate) were observed in calves fed with SL hay compared to WL hay(P0.05). Denatured gradient gel electrophoresis(DGGE) bands and richness index(S) were significantly affected by the interaction between F:C and FL(P0.05), under high F:C, band numbers and richness index from WL group were higher than that from SL group(P0.05), whereas there were no differences between WL andSL groups under low F:C(P0.05). Microflora similarity was 50–73% among the different treatments. It is concluded that the WL with high F:C(65:35) diet is suitable for weaned calves.     

Nectar secretion of RN-type cytoplasmic male sterility three lines in soybean [Glycine max (L.) Merr.]

Significant progress has been achieved in the use of heterosis in soybean and several soybean hybrids have been released in China. However, broad use of hybrid soybean seed is limited due to low seed setting of female parents. Breeding cytoplasmic male sterile(CMS) lines with high out-crossing rate is necessary to solve the problem. The objective of this study was to determine the relationship between out-crossing rate of CMS lines and their nectar secretion. The daily nectar secretion rhythm, meteorological effect on nectar secretion, and differences in nectar secretion among genotypes and years were investigated in 27 soybean CMS lines(A-lines) with their maintainers(B-lines) and restorers(R-lines). The correlation between out-crossing rate of CMS lines and nectar production was also evaluated. Nectar secretion had diurnal variation. Secretion initiated at about 06:00 for most materials and reached a peak at 07:00–08:30 after flower opened, then the nectar secretion decreased gradually. A sub-peak appeared at about 13:00, while the nectar could not be detected at 17:00. Nectar secretion was greatly influenced by the weather conditions. The amount of nectar secretion increased gradually over time during periods of high temperature and no rainfall for several days. Rainy weather and low temperatures inhibited nectar secretion. There were obvious variations of nectar amount among different genotypes tested. Significant nectar variation within a genotype among years was also observed, and the highest nectar secretion was 3-fold higher than the lowest. The amount of nectar secretion from R-lines was significantly higher than that of A-and B-lines. There was no significant difference in nectar secretion between A-and B-lines. A-and B-lines with higher out-crossing rates secreted more nectar. The amount of nectar secretion of A-and B-lines were significantly positively correlated with the out-crossing rate of A-lines.     

真空干燥过程中物料质量在线测量设备设计与试验

针对真空脉动干燥过程中物料质量在线获取易受到机械振动、温度变化和气流短时冲击等多重干扰,导致测量困难、测量精度不高的问题,提出了将固定料架和测量料架分离的测量方案,并选用高精度的测量器件,在经过信号滤波、温度修正和气流干扰排除等多种修正手段后,实现了温度变化范围20~45℃、无明显外部剧烈振动、冲击时间小于1 min的正常进抽气条件下总量程1 500 g、去掉料盘后有效量程1 000 g、最大引用误差0.1%的物料质量在线测量。静态测试结果显示,满量程最大引用误差0.06%,物料干燥测试结果显示,干燥终点最大引用误差0.1%,能够清楚反映整个干燥过程中的质量变化情况和干燥速率变化情况,可为研究农产品干燥过程中物料状态变化规律和实现自动干燥工艺调控提供技术支持。     

Development of a continuous cell line from larval Atlantic cod (Gadus morhua) and its use in the study of the microsporidian,Loma morhua

In vitro cell culture methods are crucial for the isolation, purification and mass propagation of intracellular pathogens of aquatic organisms. Cell culture infection models can yield insights into infection mechanisms, aid in developing methods for disease mitigation and prevention, and inform commercial‐scale cultivation approaches. This study details the establishment of a larval cell line (GML‐5) from the Atlantic cod (Gadus morhua) and its use in the study of microsporidia. GML‐5 has survived over 100 passages in 8 years of culture. The line remains active and viable between 8 and 21°C in Leibovitz‐15 (L‐15) media with 10% foetal bovine serum and exhibits a myofibroblast phenotype as indicated by immuno‐positive results for vimentin, α‐smooth muscle actin, collagen I and S‐100 proteins, while being desmin‐negative. GML‐5 supports the infection and development of two microsporidian parasites, an opportunistic generalist (Anncaliia algerae) and cod‐specific Loma morhua. Using GML‐5, spore germination and proliferation of L. morhua was found to require exposure to basic pH and cool incubation temperatures (8°C), in contrast to A. algerae, which required no cultural modifications. Loma morhua‐associated xenoma‐like structures were observed 2 weeks postexposure. This in vitro infection model may serve as a valuable tool for cod parasitology and aquaculture research.     

Yield Traits and Associated Marker Segregation in Elite Introgression Lines Derived from O. sativa × O. nivara

Introgression lines (ILs) derived from interspecific crosses are a source of new genetic variability. A total of 55 ILs derived from two crosses Swarna × O. nivara IRGC81848 (population A) and Swarna × O. nivara IRGC81832 (population B) were characterized for yield and yield-related traits/QTLs. Segregation of 103 simple sequence repeat (SSR) markers associated with yield-related QTLs was studied. Population A showed an average of 12.6% homozygous O. nivara alleles and population B showed 10.6%. Interestingly, three SSR markers, RM223, RM128 and RM517, showed conspicuous pattern of segregation. The distribution of parental alleles at three loci RM223, RM128 and RM517 linked to yield-related traits was unique. These markers flanked to several yield-related QTLs. RM223, flanking to qyld8.3, was heterozygous in almost all the 55 ILs except in IL10-3S and IL131S. RM128 on chromosome 1 and RM517 on chromosome 3 were mutually exclusive in 46 out of 55 ILs. These 46 ILs showed either of the marker allele RM128 or RM517 from O. nivara but not both. IL166S had both RM128 and RM517 from O. nivara and the other ILs showed homozygous Swarna allele at RM517 except IL65S. Population structure assigned the 55 ILs to three sub-populations based on their genomic diversity. IL65S, IL166S, IL248S, IL7K and IL250K showed high yields in multi-location trials, and IL248S was released for cultivation as DRRDhan 40.     

Mapping of Hd-6-2 for Heading Date Using Two Secondary Segregation Populations in Rice

Heading date is one of the most important traits for rice adaption to different cultivation areas and crop seasons. In this study, two single segment substitution lines(SSSLs), W31-41-61-3-11-3-6-7(W31-SSSL) and W32-59-80-2-11-1-10(W32-SSSL) with substituted intervals derived from the donor parents IR66897 B(W31) and IR66167-27-5-1-6(W32), respectively, with Huajingxian 74(HTX74) were found to comprise a gene for extremely late-heading date, and the gene was tentatively designated as Hd-6-2. Two secondary F2 segregating populations were developed by crossing the two heterozygous SSSLs with HJX74 to map Hd-6-2 gene. According to phenotype analysis of the two mapping populations, the late heading date trait was controlled by a major recessive gene. In the segregation population derived from W31-SSSL, Hd-6-2 was mapped on chromosome 6 between PSM677 and RM204 with the genetic distances of 1.3 and 2.7 c M, respectively. In the population of W32-SSSL, the gene for heading date was mapped to the similar region as Hd-6-2 and co-segregated with PSM672. The sequence alignment of Hd3 a in the coding domains and promoter regions of HJX74 and W31-SSSL are completely consistent, whereas there was a great difference between W32-SSSL and HJX74, suggesting that Hd3 a could hardly be the main cause of the heading date variation in W31-SSSL, but it was probably the main reason for the change of heading stage in W32-SSSL.     

Dietary eicosapentaenoic acid requirement of juvenile rock bream,Oplegnathus fasciatus

A feeding trial was conducted to evaluate the optimum dietary level of eicosapentaenoic acid (EPA, 20:5n‐3) based on growth and non‐specific immune responses in juvenile rock bream. A basal diet without EPA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g of EPA per kg diet. The actual EPA concentrations of the diets were 0.5, 4.3, 8.5, 13.0, 16.8, 21.0 and 41.2 g of EPA per kg diet, and the diets were abbreviated as EPA_0.5, EPA_4.3, EPA_8.5, EPA_13.0, EPA_16.8, EPA_21.0 and EPA_41.2, respectively. Triplicate groups of fish averaging 1.06 ± 0.01 g (mean ± SD) were fed one of the seven experimental diets at the apparent satiation for 8 weeks. At the end of the feeding trial, weight gain, specific growth rate and feed efficiency of fish fed EPA_16.8, EPA_21.0 and EPA_41.2 diets were significantly higher than those of fish fed EPA_0.5, EPA_4.3, EPA_8.5 and EPA_13.0 diets (p < .05). Superoxide dismutase activity of fish fed EPA_16.8, EPA_21.0 and EPA_41.2 diets were significantly higher than those of fish fed EPA_0.5, EPA_4.3 and EPA_8.5 diets. Fish fed EPA_21.0 and EPA_41.2 diets showed significantly higher lysozyme activity than did fish fed EPA_0.5, EPA_4.3, EPA_8.5 and EPA_13.0 diets. The broken‐line analysis of weight gain indicated that the optimum dietary EPA level was 16.7 g/kg diet. These results suggested that the optimum dietary EPA level in juvenile rock bream could be greater than 16.7 g/kg diet but less than or equal to 16.8 g/kg diet based on the broken‐line analysis and the ANOVA test of weight gain.     

低温条件下喷施乙烯利对温敏核不育水稻育性的影响

【目的】为解决我国南方温敏核不育水稻制种过程中遇低温易发生育性转换问题,对处于育性转换敏感期的温敏核不育水稻进行低温诱导并喷施不同浓度乙烯利,探讨其对温敏核不育水稻育性的影响。【方法】利用温敏核不育水稻株1S和准S为材料,在育性敏感时期对其进行连续7 d冷灌池低温(22.5℃)诱导并分别喷施乙烯合成促进物质乙烯利和抑制物质二氧化氯溶液,统计花粉可染率及套袋自交结实率,对乙烯合成关键酶进行实时荧光定量PCR分析。分离并分析了乙烯合成途径关键酶OsA CO5和Os ACS5的启动子。【结果】在22.5℃低温诱导条件下,株1S和准S连续7 d喷水处理后的可染花粉率分别是4.3%和8.9%,套袋结实率分别是1.6%和2.5%;与喷水对照相比,喷施1600 mg/L乙烯利,株1S和准S可染花粉率分别下降3.3和7.2个百分点,且都无结实;喷施1500 mg/L二氧化氯溶液的株1S和准S可染花粉率分别上升3.5和3.3个百分点,套袋结实率分别上升0.78和0.52个百分点。在低温诱导条件下(以喷水为对照),连续7 d喷施1600 mg/L乙烯利时,株1S和准S幼穗中OsA CO5和OsA CS5基因表达量显著升高,分别是对照(喷水)的1.19、1.24(株1S)和1.24、1.1(准S)倍;连续7 d喷施1500 mg/L二氧化氯溶液时,株1S和准S幼穗中Os ACO5基因表达量变化不显著,而株1S和准S中OsA CS5基因表达量显著降低,分别是对照(喷水)的93%和89%。与正常大田温度相比,在22.5℃低温诱导7 d时,喷水、喷施1600 mg/L乙烯利及1500 mg/L二氧化氯溶液处理分别会导致株1S和准S幼穗中OsA CO5和Os ACS5基因下调表达。此外,发现OsA CO5和OsA CS5的启动子除含TATA盒和CAAT盒等基本结构以外,还含有多个组织特异表达及乙烯调控顺式作用元件。【结论】低温诱导条件下,在温敏核不育水稻育性敏感期,喷施1600 mg/L乙烯利可抑制育性转换。     

引进美国玉米自交系在我国的耐旱适应性分析

对210份引进美国解密玉米自交系在正常灌溉和干旱胁迫两种水分处理下进行耐旱适应性分析。通过对美国自交系和国内主要自交系耐旱相关农艺性状调查发现,在两种水分处理下,美国自交系产量略高于国内自交系,其中,行粒数是造成产量差异的主要因素。从育种角度来看,虽然美国自交系株高高于国内自交系,但其穗位高明显低于国内自交系,有利于培育品种的抗倒性。利用耐旱选择系数对自交系耐旱性进行评价,从美国自交系选出LH149、PHBA6、S8326等26份极强耐旱性自交系,耐旱性超过国内自交系豫12和齐319等。     

化学调控剂对玉米自交系株高及穗上各节间长度的影响

以玉米自交系郑58和PH6WC为研究材料,在不同时期喷施赤霉素和乙烯利+油菜素内酯调节株高。结果表明,郑58在17片可见叶期,喷施200 mg/L赤霉素效果最佳,倒1节节间长度提升幅度与对照达显著性差异;PH6WC对赤霉素反应不敏感。郑58在14片可见叶期,喷施100 mg/L乙烯利+0.1 mg/L油菜素内酯降低株高的效果最佳,倒2节至倒6节节间长度降低幅度均与对照达显著性差异;PH6WC在17片可见叶期,喷施200 mg/L乙烯利+0.1 mg/L油菜素内酯降低株高效果最佳,倒1节至倒6节节间长度降低幅度均与对照达到显著性差异。不同自交系对化控剂处理的最佳时期和浓度均有差异。