Retrospective serological survey of Porcine circovirus-2 infection in Mexico

Postweaning multisystemic wasting syndrome (PMWS) is considered a multifactorial emerging disease of which Porcine circovirus-2 (PCV-2) is the necessary infectious cause. However, retrospective studies have shown that PMWS is not a new disease and that PCV-2 has been circulating in pig farms for years. Most of these studies were performed in Europe and Asia; only a few were performed in North or South America.     

Di-tri-octahedral smectite for the prevention of post-operative diarrhea in equids with surgical disease of the large intestine: Results of a randomized clinical trial

The aim of this study was to evaluate the effects of a commercially available di-tri-octahedral (DTO) smectite product on clinical signs and prevalence of post-operative diarrhea in horses with colic associated with disease of the large intestine. Sixty-seven horses with surgical disease of the large intestine were randomly assigned to be treated with DTO smectite (n = 37; 0.5 kg via nasogastric intubation every 24 h for 3 days post-operatively) or a placebo (n = 30). The effect of treatment on fecal scores and clinical and hematological parameters, including heart rate, mucous membrane color, temperature, total white blood cell count, total neutrophil count and total plasma protein values, were determined.Horses treated with DTO smectite had a significant reduction in the prevalence of post-operative diarrhea (10.8%), compared with controls (41.4%). A significant improvement in mucous membrane color was observed 72 h post-operatively in horses receiving treatment, compared with placebo. Administration of DTO smectite to colic patients with disease of the large intestine reduced the occurrence of diarrhea in the early post-operative period.     

A recombinant-based ELISA evaluating the efficacy of netobimin and albendazole in ruminants with naturally acquired fascioliasis

The therapeutic efficacy of albendazole and netobimin in ruminants with naturally occurring fascioliasis was investigated using a recombinant-based ELISA. The variation in the IgG response against a 2.9-kDa recombinant protein (FhrAPS), termed efficacy index (EI) 1, and the egg-output changes, termed EI 2, were used to evaluate drug efficacy.The values of EI 1 ranged between 0% and 50% in sheep, and between 0% and 30% in cattle after treatment with albendazole and netobimin. Similar EI 2 values were observed in sheep receiving albendazole or netobimin, but the highest values were found in cattle treated with netobimin. The significant reduction in the IgG response to FhrAPS found in this study shows promise in terms of developing alternative methods for evaluating the efficacy of chemotherapy against Fasciola hepatica in grazing ruminants.     

Determination of volatile organic compound patterns characteristic of five unifloral honey by solid-phase microextraction-gas chromatography-mass spectrometry coupled to chemometrics

We report the evaluation of the floral origin of honey by analysis of its volatile organic compounds (VOCs) profile, joined with the use of combined pattern recognition techniques. Honey samples, from five floral origins, were analyzed by headspace solid-phase microextraction-gas chromatography-mass spectrometry, selecting 35 VOCs out of the entire profiles, which were analyzed by hierarchical cluster analysis (HCA), stepwise discriminant analysis (SDA), and K-nearest-neighbor (KNN). Both HCA and SDA were used as exploratory tools to select a group of VOCs representing similitude and differences among studied origins. Thus, six out of 35 VOCs were selected, verifying their discriminating power by KNN, which afforded 93% correct classification. Therefore, we drastically reduced the amount of compounds under consideration but kept a good differentiation between floral origins. Selected compounds were identified as octanal, benzeneacetaldehyde, 1-octanol, 2-methoxyphenol, nonanal, and 2-H-1-benzopyran-2-one. The analysis of VOC profiles, coupled to HCA, SDA, and KNN, provides a feasible alternative to evaluate the botanical source of honey.     

Strengthening understanding and perceptions of mineral fertilizer use among smallholder farmers: evidence from collective trials in western Kenya

It is widely recognized that mineral fertilizers must play an important part in improving agricultural productivity in western Kenyan farming systems. This paper suggests that for this goal to be realized, farmers’ knowledge must be strengthened to improve their understanding of fertilizers and their use. We analyzed smallholder knowledge of fertilizers and nutrient management, and draw practical lessons from empirical collective fertilizer-response experiments. Data were gathered from the collective fertilizer-response trials, through focus group discussions, by participant observation, and via in-depth interviews representing 40 households. The collective trials showed that the application of nitrogen (N) or phosphorous (P) alone was insufficient to enhance yields in the study area. The response to P on the trial plots was mainly influenced by incidences of the parasitic Striga weed, by spatial variability or gradients in soil fertility of the experimental plots, and by interactions with N levels. These results inspired farmer to design and conduct experiments to compare crop performance with and without fertilizer, and between types of fertilizers, or responses on different soils. Participating farmers were able to differentiate types of fertilizer, and understood rates of application and the roles of respective fertilizers in nutrient supply. However, notions were broadly generated by unsteady yield responses when fertilizers were used across different fertility gradients, association with high cost (especially if recommended rates were to be applied), association of fertilizer use with hybrids and certain crops, historical factors, among other main aspects. We identified that strengthening fertilizer knowledge must be tailored within existing, albeit imperfect, systems of crop and animal husbandry. Farmers’ perceptions cannot be changed by promoting more fertilizer use alone, but may require a more basic approach that, for example, encourages farmer experimentation and practices to enhance soil properties such as carbon build-up in impoverished local soils.     

Genetic mapping,marker assisted selection and allelic relationships for the Pu6 gene conferring rust resistance in sunflower

Rust resistance in the sunflower line P386 is controlled by Pu₆, a gene which was reported to segregate independently from other rust resistant genes, such as R₄. The objectives of this work were to map Pu₆, to provide and validate molecular tools for its identification, and to determine the linkage relationship of Pu₆ and R₄. Genetic mapping of Pu₆ with six markers covered 24.8 cM of genetic distance on the lower end of linkage Group 13 of the sunflower consensus map. The marker most closely linked to Pu₆ was ORS316 at 2.5 cM in the distal position. ORS316 presented five alleles when was assayed with a representative set of resistant and susceptible lines. Allelism test between Pu₆ and R₄ indicated that both genes are linked at a genetic distance of 6.25 cM. This is the first confirmation based on an allelism test that at least two members of the R_adv/R₄/R₁₁/ R_13a/R_13b/Pu₆ cluster of genes are at different loci. A fine elucidation of the architecture of this complex locus will allow designing and constructing completely new genomic regions combining genes from different resistant sources and the elimination of the linkage drag around each resistant gene.     

Organogenesis and foetal haemodynamics during the normal gestation of healthy black‐rumped agoutis (Dasyprocta prymnolopha,Wagler, 1831) bred in captivity

The objective of this study was to define the patterns of organogenesis and foetal haemodynamics during the normal gestation of healthy agoutis (Dasyprocta prymnolopha) kept in captivity. Thirty pregnant agoutis that ranged in size from small to medium and weighed between 2.5 and 3 kg underwent B‐mode and Doppler ultrasonography for the biometric evaluation of the foetal organs. The foetal aortic blood flow proved to be predominantly systolic, and the measured flow velocity was 78.89 ± 2.95 cm/s, with a maximum pressure gradient of 2.12 ± 0.27 mmHg. The liver was characterized by its large volume, occupying the entire cranial aspect of the abdominal cavity, and it was associated cranially with the diaphragm and caudally with the stomach. The flow velocity in the portal vein was estimated to equal 12.17 ± 2.37 cm/s, with a resistivity index of 0.82 ± 0.05. The gallbladder was centrally located and protruded cranially towards the diaphragm. The spleen was visualized as an elongated structure with tapered cranial and caudal extremities, and the foetal kidneys were visualized bilaterally in the retroperitoneal region, with the right kidney positioned slightly more cranially than the left. The morphological characterization and hemodynamic analysis of the foetal organs of black‐rumped agoutis via B‐mode and Doppler ultrasonography allow determination of the vascular network and of reference values for the blood flow required for perfusing the anatomical elements essential for maintaining the viability of foetuses at different gestational ages.     

Foraging behavior of heifers with or without social models in an unfamiliar site containing high plant diversity

Grazing behavior, diet selection and weight gain of heifers (with or without social models) were assessed in an unfamiliar site containing high plant diversity. The study was performed within a tropical forest ecosystem containing a mixture of grass forb/herb, shrub and tree species. Ten inexperienced crossbred Bos taurus × Bos indicus heifers (7 ± 1 months old) were randomly assigned to one of two groups: naive or naive + social model (sm) and two experienced heifers (16 months old) were assigned to the second group. Naive heifers were bottle-nursed from days 2 to 90 after birth and began grazing at 1 month of age in tropical grass monocultures, while experienced animals had been foraging in sites containing a high diversity of plant species for 3 months prior to the study. Each group grazed in separate paddocks for a 12-week period during the rainy season, and animals were observed using focal sampling from 7:00 to 19:30 h to assess diet composition based on bite counts. Weight gain was assessed every 14 days. Paddocks contained from 1481 to 1789 kg/ha of herbaceous dry matter, enough to support the heifers throughout the study without affecting diet selection. Shrub and tree cover ranged from 55.2 to 58.4% across treatments. Bites per minute were adjusted to a log-scaled quadratic-plateau model and the curves showed no differences between treatments (P = 0.756). However, diet composition differed between groups (P < 0.001), with naive + sm heifers ingesting a greater proportion of trees (P < 0.001) and shrubs (P = 0.02), while naive heifers ingested more forb/herbs (P = 0.02); no difference in grass consumption was observed (P = 0.92). Heifers in both treatments consumed the same plant species (50 from 26 families). Over time, utilization of several plant species increased or decreased (P < 0.05), eventually leveling off for the remainder of the study. Although differences in diet composition were observed, they did not affect overall weight gain (117 and 113 g/day in the naive and naive + sm groups, respectively; P = 0.913). However, initial post-weaning weight loss was avoided in the naive + sm group. Social learning facilitates a higher use of shrubs and trees in tropical pastures containing a high diversity of plant species with different growth habits. As many plant species have high potential as forage, more effort should be placed on developing mechanisms to increase their dietary inclusion by cattle.     

Evaluation of lufenuron as a chemosterilant against fruit flies of the genus Anastrepha (Diptera: Tephritidae)

BACKGROUND: Chemosterilisation with lufenuron bait stations is a recently developed technique that is being implemented for Ceratitis capitata Wiedemann control. The aim of this work was to evaluate the chemosterilising effect of lufenuron against four economically important Latin American fruit flies species: Anastrepha ludens (Loew.), A. obliqua Macquart, A. serpentina Wiedemann and A. striata Schiner (Diptera: Tephritidae) in order to design a similar strategy for their control. RESULTS: Sexually mature adults were treated by ingestion with concentrations ranging from 0.1 to 30.0 mg g^?1 of lufenuron in the diet. In addition, conspecific crosses with only one of the sexes being treated (30.0 mg g^?1) were performed in order to appraise the contribution of each sex to the sterilising effect. In all cases, fecundity was not affected by the treatments, as opposed to fertility where all Anastrepha species studied were significantly affected, although to different extents. The conspecific crosses showed that treated males of A. ludens, A. obliqua and A. serpentina were not able to transmit the sterility to their respective untreated females. Only in the case of A. striata did crossing treated males with untreated females significantly reduced egg hatch. CONCLUSION: Although further investigations are required, the present results demonstrate that the use of lufenuron for controlling A. striata could be potentially viable. Copyright © 2010 Society of Chemical Industry