RESUMO
Little has been studied about microclimate and the thermal comfort during the implementation of silvopastoral systems. This study aimed to evaluate the microclimate and thermal comfort during the implementation of High Biodiversity Silvopastoral System with Nuclei (SPSnu). Three treatments were investigated, SPSnu with 5 and 10% of the pasture area with nuclei, (SPSnu5 and SPSnu10, respectively), and treeless pasture (TLP). Each treatment was subdivided into 4 areas: within the nuclei, around the nuclei, around the nuclei with shade and internuclei. The analyzed variables were soil surface temperature, air temperature, wind speed, relative humidity, black globe temperature and the Heat Load Index (HLI) at 20 and 120 cm height. We hypothesized that the wind speed reduction associated with insufficient shade projection typical of the first years of SPSs may interfere in microclimate and thermal comfort during the hot seasons. SPSnu5 and SPSnu10 had a reduction in wind speed of 51.58% and 68.47% respectively when compared to TLP at 20 cm. Soil surface temperature and air temperature at 120 cm were higher for SPSnu than TLP. The same effect was observed for the HLI. At 20 cm, HLI indicated better thermal comfort in TLP than in the SPSnu treatments. The lack of shade projection from young nuclei in conjunction with the decrease of wind speed between the nuclei caused a higher air temperature and HLI in the SPSnu treatments, we called this conditions, windbreak countereffect. Farmers must knowledge this effect when implementing SPSs, and when necessary, mitigate with the proper management decisions.
RESUMO
Chickens are a host that is very resistant to the development of clinical toxoplasmosis. Free-range chickens have been used to indirectly track environmental contamination with Toxoplasma gondii oocysts because they feed on the ground. This study evaluated the genetic diversity of T. gondii isolates from free-range chickens from Florianópolis island in Santa Catarina state, southern Brazil. Sera from 21 chickens were tested for IgG anti-T. gondii antibodies using the modified agglutination test (MAT). Tissue homogenates from the 11 seropositive birds (MAT titres ≥5) were bioassayed in mice. The four obtained isolates (TgCkBrSC1-4) were genotyped using 11 PCR-RFLP markers and 15 microsatellite markers (MS). Four genotypes were identified, three of which are typical Brazilian genotypes (ToxoDB-RFLP #26 and #53 were previously reported and #278 is new), and the other is the rare clonal type I genotype. This type I isolate was considered a variant according to MS analysis, with two atypical alleles, which emphasizes the genetic diversity of the parasite in Brazil. The genetic variability of T. gondii in South America may be related to the high occurrence of severe ocular and congenital toxoplasmosis in humans in this region. High human seroprevalence and frequency of ocular toxoplasmosis are reported in southern Brazil, but there is limited information on the T. gondii strains that are circulating in this region, so more studies should be conducted to identify the strains in different hosts and in human toxoplasmosis cases.
