Large males dominate: ecology,social organization,and mating system of wild cavies,the ancestors of the guinea pig

Ecological factors differently affect male and female animals and thereby importantly influence their life history and reproductive strategies. Caviomorph rodents are found in a wide range of habitats in South America and different social and mating systems have evolved in closely related species. This permits to study the impact of ecological factors on social evolution. In this study, we investigated the social organization and the mating system of the wild cavy (Cavia aperea), the ancestor of the domestic guinea pig, in its natural habitat in Uruguay. Based on our laboratory investigations, we expected a polygynous system with large males controlling access to females. Results from radiotelemetry and direct observations showed that females occupied small stable home ranges which were largely overlapped by that of one large male, resulting in a social organization of small harems. In some cases, small satellite males were associated with harems and intermediate-sized roaming males were occasionally observed on the study site. However, microsatellite analyses revealed that offspring were exclusively sired by large males of the same or neighboring harems, with a moderate degree of multiple paternity (13–27%). Thus, the mating system of C. aperea can be described as polygynous and contrasts with the promiscuous organization described for other species of cavies (Cavia magna, Galea musteloides and Microcavia australis) living under different ecological conditions. Our findings stress the strong impact of environmental factors on social evolution in Caviomorphs as resource distribution determines female space use and, thereby, the ability of males to monopolize females. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A comparative study of microbial communities in soils amended by manures from pigs fed with organic versus synthetic feeds

We applied pyrosequencing to determine bacterial communities in soil samples taken from test fields amended by manures of pigs fed with green feeds (GPMS), synthetic feeds (APMS), and the reference field without swine manure amendment (NPMS), respectively. For each sample, 7050 effective sequences were selected and utilized to do the bacterial diversity and abundance analysis, respectively. In total, 2986, 2873, and 1602 operational taxonomic units were obtained at a 3% distance cut-off in GPMS, APMS, and NPMS, respectively. Bacterial phylotype richness in GPMS was higher than the other samples. NPMS had the least richness. The most dominant class in both GPMS and APMS is Betaproteobacteria, whereas Alphaproteobacteria is dominant in NPMS. Circa 7.5% sequences in GPMS were found to be affiliated with Burkholderiales order. Bacterial diversity and abundance in the soil varied with swine manure amendment, due to nutrient elements as well as toxic metals in swine manures. Compared with the soil amendment by manures from pigs bred with synthetic feeds, more bacterial diversity but less potentially pathogenic bacterial genera in the soil amended by manures of pigs fed with green feeds were found, which indicated that these manures were better land-applied organic fertilizers.     

厌氧氨氧化工艺处理猪场废水沼液的试验研究

本文以实际猪场沼气废水为研究对象,以ASBR为反应器,接种厌氧消化污泥培养厌氧氨氧化细菌,厌氧氨氧化阶段成功启动后,研究了厌氧氨氧化脱氮最佳运行工艺。试验研究表明,厌氧氨氧化反应适宜的温度在35（±1）℃之间,适宜的pH在7．5—8．0之间,HRT选用24h。当达到最佳运行参数时,NH4＋-N的去除率达到87．6％,NO2- -N的去除率达到99．96％。     

生物沥浸法去除猪粪中重金属的研究

探讨以猪粪为培养介质,驯化和加富培养获得硫细菌混合菌液,并研究其对猪粪中重金属的生物沥浸效果。结果表明：猪粪可以在18 d内完成驯化,经3轮富集培养的猪粪粪液可作为硫细菌接种菌液。采用此菌液对猪粪粪液接种并投加硫粉,经过9 d的生物沥浸,Cu、Zn和Cd的沥出率分别达到93.0%、90.1%和67.8%。     

鸡粪与猪粪所含土霉素在土壤中降解的动态变化及原因分析

采用室内模拟培养实验,研究不同用量鸡粪与猪粪所含土霉素在土壤中降解的动态变化规律及消解途径.结果表明,畜禽粪便中土霉素在土壤中能迅速进入降解期,含量变化呈"L"型,但不同粪肥种类和用量处理的降解率和变化幅度有显著差异(P<0.05).180 d时,鸡粪处理土壤中OTC的降解率高于猪粪处理,半衰期分别为26.98 d和31.32 d.低用量鸡粪和猪粪处理土壤中OTC降解率最大,对应分别可达84.06%和80.47%.降解率与畜禽粪便用量呈负相关,与时间呈正相关且可用v=A+Blnt回归方程拟合(r>0.96).土霉素进入土壤50 d时,光降解量占减少总量的20.03%,下降了25.05%;微生物降解量占3.16%,增加了2.50%.可见,鸡粪所含土霉素在土壤中的降解情况好于猪粪,光照对土壤中土霉素有较好的降解作用,土壤微生物降解作用很小,且随着培养时间的延长,微生物降解增加,光降解减弱.     

冀东某县农村养殖粪污处理环境风险与对策研究

生猪养殖粪污是农村面源污染来源之一,冀东某县是河北省养猪大县,养殖产生的粪污主要采用能源生态处理方式进行处理与利用,在养殖粪污的现有利用方式中,存在土壤中重金属积累风险、粪便中病菌抗生素风险、生猪散养的环境风险.针对冀东某县生猪养殖粪污处理利用存在的环境风险,对规模化养殖场采用粪便堆肥发酵制有机肥工艺进行处理利用;散养型粪污,依托规模化养殖场进行处理利用;政府依据种养结合的原则,制定养殖规划,确定养殖规模,建立制度化管理,保护农村环境.     

生物沥浸法去除不同初始pH值猪粪中的重金属

试验研究了不同初始pH值下猪粪中Cu、Zn和Cd的生物沥浸效果,结果表明猪粪生物沥浸对初始pH值的要求并不严格,具有较广的适用范围。猪粪粪液即使在初始pH值为8的弱碱性条件下,其pH值也可随沥浸时间快速降低,生物沥浸12天降到1.37,Cu、Zn和Cd沥出率可达到90.76%、97.97%和80.45%。初始pH值对重金属的沥浸速率有一定影响,降低初始pH值可以缩短生物沥浸周期,重金属的沥浸周期受不同初始pH值的影响程度从大到小依次为:CuZnCd。初始pH值为5的猪粪粪液可以在9天内完成生物沥浸,Cu、Zn和Cd沥出率可达到93.83%、99.24%和70.98%     

Microbial population dynamics and changes in main nutrients during the acidification process of pig manures

This study evaluated the impact of pig manure acidification on anaerobic treatment and composition of the fecal microbial community.According to the different chemical oxygen demand (COD) in the anaerobic treatment processes,pig manure was diluted 4 times (×4),16 times (×16),or 64 times (×64) and subjected to acidification.During the acidification process,pH,soluble chemical oxygen demand (SCOD),volatile fatty acids (VFAs),nitrogen (N),phosphorus (P) and potassium (K) were determined along with microbial po...     

Effect of phosphogypsum and dicyandiamide as additives on NH3, N2O and CH4 emissions during composting

A laboratory scale experiment of composting in a forced aeration system using pig manure with cornstalks was carried out to investigate the effects of both phosphogypsum and dicyandiamide (DCD, C2H4N4) as additives on gaseous emissions and compost quality. Besides a control, there were three amended treatments with different amounts of additives. The results indicated that the phosphogypsum addition at the rate of 10% of mixture dry weight decreased NH₃ and CH₄ emissions significantly during composting. The addition of DCD at the rate of 0.2% of mixture dry weight together with 10% of phosphogypsum further reduced the N₂O emission by affecting the nitrification process. Reducing the phosphogypsum addition to 5% in the presence of 0.2% DCD moderately increased the NH₃ emissions but not N₂O emission. The additives increased the ammonium content and electrical conductivity significantly in the final compost. No adverse effect on organic matter degradation or the germination index of the compost was found in the amended treatments. It was recommended that phosphogypsum and DCD could be used in composting for the purpose of reducing NH₃, CH₄ and N₂O emissions. Optimal conditions and dose of DCD additive during composting should be determined with different materials and composting systems in further study.     

Recombinant human AhR-mediated GUS reporter gene assays for PCB congeners in transgenic tobacco plants in comparison with recombinant mouse and guinea pig AhRs

Four expression plasmids for recombinant human aryl hydrocarbon receptor (hAhR) consisting of a ligand binding domain of hAhR, a DNA-binding domain of LexA and a transactivation domain of VP16 as well as β-glucuronidase (GUS) reporter genes were constructed. All the expression plasmids were transformed into tobacco plants. The selected transgenic tobacco plants were used to assay. PCB congeners showed GUS activity in a TEF-dependent manner. The selected transgenic tobacco plant XhD4V17 was compared with the transgenic tobacco plants XmD4V26 and XgD2V23 containing recombinant mouse (m) AhR-mediated GUS reporter gene expression cassette and recombinant guinea pig (g) AhR-mediated GUS reporter gene expression cassette for PCB congener-inducible GUS activity. The data revealed that the tobacco plant XgD2V23 was the most active in PCB congener-inducible GUS activity. In a 1:1 mixture of PCB126 and PCB80 a reduced PCB126-induced GUS activity was observed in plant XgD2V23, which could possibly be due to interaction between PCB126 and PCB80.