A combination of plant oils promotes adequate growth of the freshwater catfish Rhamdia quelen (Quoy & Gaimard 1824)

Essential fatty acids should be included in the diet to ensure adequate fish growth. Despite the great number of studies on fatty acid nutrition of fish, there are still several unknowns. The aim of the present study was to investigate fatty acid nutrition of jundiá, a Latin American freshwater catfish. Four diets were formulated containing (i) coconut oil (?C, negative control), (ii) coconut oil + high‐docosahexaenoic‐acid‐fish oil (+C, positive control) and coconut + sunflower + linseed oils at different ratios, producing either (iii) a diet rich in linoleic acid (LA) (HighLA) or 4) a diet low in LA (LowLA). All diets contained significant amounts of saturated fatty acids (at least 57.5% total fatty acids in HighLA) and monounsaturated fatty acids (at least 19.1% total fatty acids in ?C). Diets were fed to jundiá fingerlings (1.5 g) for 70 days; growth, body composition and liver histology were evaluated. The ?C diet, without essential fatty acids, promoted significantly lower fish growth, body fat accumulation and hepatic lipidosis. Fish fed HighLA and LowLA diets presented similar growth as fish fed +C diet. These findings suggest that diet formulations for jundiá catfish fingerlings can include only plant oils without negative effect on growth, survival, body composition, fish health or parameters of feed utilization (ingestion rate and protein utilization).     

Phosphorus fractions in Brazilian Cerrado soils as affected by tillage

No-tillage systems lead to physical, chemical and biological changes in soil. Soil fertility is responsive to changes in tillage as it depends on nutrient status, soil water content and biological characteristics. This work aimed to determine long term changes in phosphorus forms and availability in the profile of two tropical soils under conventional and no-till systems, and to discuss the significance of these changes on plant growth and demand for P fertilizers. Undisturbed soil cores with 20 cm in diameter were collected to a depth of 40 cm, accommodated in PVC tubes and taken to a greenhouse, where the experiment was conducted. Two soils were collected in Central Brazil, in areas under Cerrado. Both soils had been cropped for at least 10 years under conventional tillage and no-till. In the greenhouse, pots received phosphorus fertilization or not at 43.7 kg ha⁻¹, and soybean was grown for 60 days, when soil P fractions were determined. Labile P fractions in the soil profile were not affected by management systems, and there was no accumulation of available P under no-till. A large amount of P added as fertilizer was adsorbed in soil and remained in moderately labile fractions, mainly on uppermost soil layers. Therefore, the phosphate fertilizer has promoted P accumulation on less available fractions in soil, remaining P on the soil after crop harvest. Eventually this phosphorus could migrate to more labile fractions and be available for crops grown in succession.     

Frequency of BCoV detection by a semi-nested PCR assay in faeces of calves from Brazilian cattle herds

Bovine coronavirus (BCoV) is one of the main causes of neonatal calf diarrhoea. Several diagnostic assays have been employed to detect the presence of the virus in stool samples from calves. Despite this, the frequency of BCoV infection among Brazilian and even South American cattle herds has yet to be well characterised. This study describes the occurrence of BCoV infection among calves from dairy and beef herds in four Brazilian states. A total of 282 stool samples from 1 to 60-day-old calves were evaluated for the presence of BCoV by a semi-nested (SN) PCR assay. The animals were from herds (n = 23) located in three geographical regions in Brazil (south, southeast, and center-west). The specific BCoV amplicon was detected in 15.6% (44/282) of the faecal specimens examined, of which 95.4% (42/44) were from diarrhoeic and 4.6% (2/44) from asymptomatic calves. The specificity of the SN-PCR amplicons was evaluated by restriction fragment length polymorphism (RFLP) analysis. The results show that the BCoV is widespread, mainly among calves from 16 to 30-days-old (p = 0.0023), and verify the association between BCoV infection and clinical signs of diarrhoea (p = 0.005). These findings emphasise the importance of this virus in enteric infections of Brazilian cattle herds.     

Differences in phagocytosis susceptibility in Haemophilus parasuis strains

Haemophilus parasuis is a colonizer of the upper respiratory tract of healthy pigs, but virulent strains can cause a systemic infection characterized by fibrinous polyserositis, commonly known as Glässer’s disease. The variability in virulence that is observed among H. parasuis strains is not completely understood, since the virulence mechanisms of H. parasuis are largely unknown. In the course of infection, H. parasuis has to survive the host pulmonary defences, which include alveolar macrophages, to produce disease. Using strains from different clinical backgrounds, we were able to detect clear differences in susceptibility to phagocytosis. Strains isolated from the nose of healthy animals were efficiently phagocytosed by porcine alveolar macrophages (PAM), while strains isolated from systemic lesions were resistant to this interaction. Phagocytosis of susceptible strains proceeded through mechanisms independent of a specific receptor, which involved actin filaments and microtubules. In all the systemic strains tested in this study, we observed a distinct capsule after interaction with PAM, indicating a role of this surface structure in phagocytosis resistance. However, additional mechanisms of resistance to phagocytosis should be explored, since we detected different effects of microtubule inhibition among systemic strains.     

Establishment of a proteomic reference map for the gastrocnemius muscle in the rabbit (Oryctolagus cuniculus)

In several laboratory and production species, the establishment of a proteome reference map of a specific tissue has been accomplished. The rabbit is widely used as both a production and experimental animal. A lot of physiology research involving the gastrocnemius muscle of rabbit is described, although no reference proteome map is available. In this work, the first reference map of the rabbit’s gastrocnemius muscle using 2D gel electrophoresis and the identification of proteins through peptide mass fingerprinting (PMF) was established. A total of 45 proteins were localized and identified with three major roles: cell structure and contractile apparatus; metabolic and cell defense proteins. A reference map of major proteins expressed is described enabling possible comparisons with other physiological studies.