Silages in the form of diet based on spineless cactus and buffelgrass

This study was conducted to evaluate the fermentation pattern and the in situ dry matter degradability of silages in the form of diet. Five diets were formulated based on spineless cactus (Opuntia fícus-indica cv. ‘Gigante’) and buffelgrass (Cenchrus ciliaris). The experimental design was completely randomised, with five treatments and three replicates in which the diets differed in the proportion of buffelgrass (0%, 15%, 25%, 30% and 35%, on a fresh matter basis). There was significant difference (p < 0.05) in the chemical composition of the diets, with all dry matter contents being within the ideal range. Ammonia-nitrogen content was not affected (p > 0.05). There were significant differences (p < 0.05) in dry matter recovery across diets, which ranged from 96.28% to 99.93%. The pH values decreased as the time of opening (days) was extended. Organic acid contents differed across all diets; however, overall, all diets showed satisfactory lactic acid contents. As the proportion of buffelgrass in the diets was increased, the degradability of dry matter decreased. Based on fermentation profile, losses and chemical composition the diet with higher proportion of spineless cactus can be recommended for silage production.     

Use of survival analysis as a tool for the genetic improvement of age at first conception in Nellore cattle

Restricted breeding seasons in beef cattle lead to censoring of reproductive data. In this paper, age at first conception (AFC) of Nellore females exposed to the sires for the first time between 11 and 16 months of age, was studied aiming to verify the possibility of genetically advance sexual precocity using a survival model. The final data set contained 6699 records of AFC in days. Records of females that did not calve in the next year following exposure to the sire were considered censored (77.5% of total). The model used was a Weibull mixed survival model including effects of contemporary groups, period (fixed) and animal (random). The effect of the contemporary groups on AFC was important (p < 0.01). Heritabilities were 0.51 and 0.76 in logarithmic and original scales respectively. Results indicate that it is possible to genetically advance sexual precocity, using the outcome of survival analysis of AFC as selection criterion. They also suggest that improvements of the environment could advance sexual precocity too, thus an adequate pregnancy rate for farmers could quickly be achieved.     

干辣椒风味物质气相色谱及质谱方法的研究

用嗅觉测量法-气相色谱联用(GC-O),火焰离子检测器-气相色谱联用(GC-FID),质谱-气相色谱联用(GC-MS)三种气相色谱检测方法和常压化学离子化飞行时间质谱(APCI-TOFMS),质子传递反应质谱(PTR-MS)两种直接质谱检测方法来比较测定干辣椒中的挥发性香味成分。干辣椒的挥发性香味成分的大体描述最后由感官评定来确定。三种较显著的风味分别是:辣椒味、煮熟蔬菜味和青草味。用气质联用顶空分析法共有63种挥发性香味成分被分离出来。而嗅觉测量法-气相色谱联用(GC-O)认为其中的11种成分决定了辣椒的香味活跃程度。在所有的方法中普遍认为:3-甲基正丁醛是最活跃的香味成份,其次是2-甲基正丁醛。确定挥发性香味成分的多少主要是受测定方法的影响。色谱方法之间有很强的相关性(ρ=0.946)。直接质谱法相关性不显著(ρ=0.613)。经过不同方法的分析,我们发现,用GC-MS,GC-FID和PTR-MS三种方法检测出的挥发性香味成分并没有显著的不同,显著性的差异主要存在于PCI-TOFMS法和其工艺的不同(P<0.01).(Int J Mass Spectrom223-224(2003)55-65)     

Dunging gutters filled with fresh water in finishing barns had no effect on the prevalence of Salmonella enterica on Brazilian swine farms

Our aim was to assess the importance of dunging gutters filled with water in finishing barns for the prevalence of pigs shedding Salmonella enterica. Some finishing barns in Brazil are provided with a dunging-gutter system which consists of a continuous water flow at the back of solid-floored adjacent pens. Because there is transfer of faecal material between adjacent pens by water in this system and the faecal-oral route of transmission is so important for enteric pathogens, we tested the hypothesis that the presence of this kind of dunging-gutter system in finishing barns affects the prevalence of slaughter-age pigs shedding salmonella organisms in their faeces. The cross-sectional study was conducted on six farms each having barns with and barns without a dunging-gutter system. Breeding, management, nutritional and seasonal factors were similar in both barns on each farm. The two systems did not differ in prevalence of pigs shedding salmonella organisms. Five S. enterica serotypes were isolated: S. Agona, S. Javiana, S. Rissen, S. Sandiego and S. Senftenberg.     

Growth and Chemical Composition of Spirulina Maxima and Spirulina Platensis Biomass at Different Temperatures

The influence of temperature on growth and biomass composition of two species of Spirulina, S. maxima and S. platensis used for food was studied. A 4L fermenter with temperature and agitation control was used to cultivate both species. Under continuous light, maximum cell production of 2.4 g l^–1 was verified for both cultures studied at temperatures above 25 °C: S. maxima (30 °C and 35 °C) and S. platensis (25 °C and 30 °C). An accentuated lag phase was observed for all cultures at lower temperatures (15–20 °C), and a maximum biomass production of 1.5 g l^–1 was achieved. It was also observed that an increase of temperature caused a marked decrease in protein content, while carbohydrate synthesis was stimulated. The concentration of -linolenic acid varied from 11–16% for S. maxima and from 12–14% for S. platensis, at the optimum growth temperatures. Greater culture volumes were also studied in order to compare the performance of glass and plastic containers. At optimum growth temperature, S. maxima produced the same cell growth and similar final biomass composition.     

Characterization of Pterocarpus macrocarpus (pradoo wood) biochar and its effect on the retention properties of sandy soils in Northeast Thailand

Pradoo wood biochar has been tested in order to explore sustainable solutions to the development of agriculture on poor sandy soils in marginal areas in Northeast Thailand. Some basic physicochemical properties of biochar, for example pore size distribution, cation exchange capacity (CEC), specific surface area (SSA), and water and nutrient adsorption, were determined and compared to soil properties in order to determine appropriate biochar application to soil. Pradoo wood biochar showed important adsorption properties with high SSA, CEC and nutrient adsorption. The water retention properties were also improved on the dry end of the water retention curve. Phosphorous and ammonium adsorption–desorption isotherms were established and their respective affinity for the biochar surface was quantified, by the means of a retention index and thermodynamical parameters. We found that despite excellent retention properties, biochar needs to be added in large amounts (between 10 and 70 kg m⁻²) to soil to be able to modify noticeably the resulting soil properties.     

Tick saliva induces regulatory dendritic cells: MAP-kinases and Toll-like receptor-2 expression as potential targets

Ticks (Acari: Ixodidae) are bloodsucking ectoparasitic arthropods of human and veterinary medical importance. Tick saliva has been shown to contain a wide range of bioactive molecules with vasodilatory, antihemostatic, and immunomodulatory activities. We have previously demonstrated that saliva from Rhipicephalus sanguineus ticks inhibits the maturation of dendritic cells (DCs) stimulated with LPS. Here we examined the mechanism of this immune subversion, evaluating the effect of tick saliva on Toll-like receptor (TLR)-4 signalling pathway in bone marrow-derived DCs. We demonstrated that R. sanguineus tick saliva impairs maturation of DCs stimulated with LPS, a TLR-4 ligand, leading to increased production of interleukin (IL)-10 and reduced synthesis of IL-12p70 and TNF-α. The immunomodulatory effect of the tick saliva on the production of pro-inflammatory cytokines by DCs stimulated with LPS was associated with the observation that tick saliva inhibits the activation of the ERK 1/2 and p38 MAP kinases. These effects were independent of the expression of TLR-4 on the surface of DCs. Additionally, saliva-treated DCs also presented a similar pattern of cytokine modulation in response to other TLR ligands. Since the recent literature reports that several parasites evade immune responses through TLR-2-mediated production of IL-10, we evaluated the effect of tick saliva on the percentage of TLR-2⁺ DCs stimulated with the TLR-2 ligand lipoteicoic acid (LTA). The data showed that the population of DCs expressing TLR-2 was significantly increased in DCs treated with LTA plus saliva. In addition, tick saliva alone increased the expression of TLR-2 in a dose- and time-dependent manner. Our data suggest that tick saliva induces regulatory DCs, which secrete IL-10 and low levels of IL-12 and TNF-α when stimulated by TLR ligands. Such regulatory DCs are associated with expression of TLR-2 and inhibition of ERK and p38, which promotes the production of IL-10 and thus down-modulates the host's immune response, possibly favouring susceptibility to tick infestations.     

Retention of eucalyptus harvest residues reduces soil compaction caused by deep subsoilingOA

Eucalyptus harvesting,forwarding and soil tillage operations are among the main causes for compaction of forest soils,with potential impacts on productivity.This concern is especially important in areas with soils that are naturally compacted(fragipans and duripans).In these soils,tillage operations include the use of subsoilers that can reach depths of more than one meter and require heavy tractors that exert high pressure on the soil.One of the ways to try to minimize the effect of this compac...     

Molecular marker-assisted selection for development of common bean lines resistant to angular leaf spot

The objective of this work was to develop homozygous common bean lines carrying angular leaf spot resistance genes derived from the cultivars ‘Mexico 54’, ‘MAR 2’ and ‘BAT 332’ through marker‐assisted selection. Molecular markers SCAR OPN02₈₉₀, RAPD OPE04₅₀₀ and OPAO12₉₅₀ linked to the resistance genes of ‘Mexico 54’, ‘MAR 2’ and ‘BAT 332’, respectively, were used in segregating backcross‐derived populations to selection. DNA fingerprinting was used to select homozygous BC₂F₃ and BC₁F₃ resistant plants genetically closer to the recurrent parent. Two homozygous BC₂F_2:3 and two and five BC₁F_2:3 families derived from ‘Ruda’ vs. ‘Mexico 54’ (RM), ‘MAR 2’ (RMA) and ‘BAT 332’ (RB) crosses were selected, respectively. After only one (RMA, RB) or two backcrosses (RM), five and eight BC₁F₃ lines derived from RMA and RB, respectively, and seven BC₂F₃ lines derived from RM, with 14.9–16.6, 16.9–18.6 and 9.3–11.1% of relative genetic distances to the recurrent parent were selected. This is the first report of lines resistant to angular leaf spot carrying genes of the cultivars ‘Mexico 54’, ‘MAR 2’ and ‘BAT 332’ developed with the aid of molecular markers.