RESUMO
The aim was to evaluate the chemical composition, carbohydrates, protein fractionation and in vitro gas production of silages composed of spineless cactus and tropical forages and their effect on sheep performance. Treatments consisted of silages: corn silage (CS), spineless cactus silage (SCS), spineless cactus + gliricidia (SCG), spineless cactus + buffel grass silage (SCBG) and spineless cactus + pornunça (SCP). Silos were opened 60 days after ensiling, and analyses were carried out. The digestibility test lasted for 36 days, with eight animals per treatment. A completely randomized design was adopted. Considering carbohydrate fractionation, CS, SCS and SCBG silages had higher total carbohydrate content (p = 0.001). The SCS silage presented a higher A + B1 fraction (p = 0.001). The SCBG and SCG silages showed a higher B2 fraction (p < 0.0001) compared to the CS and SCS silages. The SCBG and SCP silages presented a higher C fraction (p = 0.001). For protein fractionation, the SCP and SCG silages showed higher crude protein contents (p = 0.001). The CS and SCS silages showed a higher A fraction (p = 0.001). The SCBG silage presented a higher B1 + B2 fraction (p = 0.001). The SCG silage showed a higher B3 fraction (p = 0.006) compared to SCBG silage. The SCS and SCP silages showed a higher C fraction (p = 0.001). Exclusive SCS silage showed higher in vitro dry matter digestibility (p = 0.001), dry matter degradability (p = 0.001) and total gas production (p = 0.001). The use of the SCBG, SCP and SCG silages to feed sheep increased the dry matter intake (p < 0.001). Sheep fed the SCG silage showed greater dry matter and crude protein digestibility compared to the sheep fed the CS, SCS and SCP silages (p = 0.002). There was a higher water intake (p < 0.001) with the use of the SCS and SCG silages to feed the sheep. The SCP and SCG silages provided a greater intake (p < 0.001) and excretion (p < 0.001) of nitrogen by the animals. Although there were no differences between the treatments for daily gains, lambs that received the spineless cactus-based silage associated with tropical forages showed higher gains (160-190 g/day) than lambs that received CS silage (130 g/day). Thus, the use of spineless cactus associated with buffelgrass, pornunça and gliricidia to prepare mixed silages (60:40) to feed sheep has potential use to feed sheep, with positive effects on nutrient degradation and increases in dry matter intake. Under experimental conditions, we recommend the exclusive use of spineless cactus silage associated with buffel grass, pornunça and gliricidia in feeding sheep in semi-arid regions, as it provides nutrients, water and greater daily gains compared to corn silage.
RESUMO
The present study aimed to evaluate biochemical and genotoxic effects of the herbicides atrazine (ATZ) and Roundup(®) (RD) separately, as well as their mixture, on the freshwater clam Corbicula fluminea after 96 h exposure. Animals were exposed to 2 and 10 ppb of ATZ (ATZ2 and ATZ10), 2 and 10 ppm of RD (RD2 and RD10) and the following mixtures: 2 ppb ATZ+2ppm RD (AR2) and 10 ppb ATZ+10 ppm RD (AR10). Activities of ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR), as well as the multixenobiotic resistance mechanism (MXR), reduced glutathione concentrations (GSH) and lipid peroxidation (LPO) were measured in gills and digestive gland. DNA damage was determined in clams hemocytes through the comet assay. The gills were more susceptible to the action of the herbicides and the results showed that ATZ2 and ATZ10 caused a significant reduction in EROD and the mixture leads to a significant decrease in EROD and MXR. No significant change in the biotransformation parameters was observed in the digestive gland. Regarding the primary antioxidant defenses, SOD activity increased in the gills of clams exposed to ATZ10 and RD10 and in the digestive gland of animals exposed to RD2 and RD10, CAT activity was significantly reduced only in digestive gland of clams exposed RD10 while GPX increased in the gills after exposure to ATZ2 and RD10. The exposure to RD10 caused a significant increase in LPO in both gills and digestive gland. While the exposure to ATZ and RD separately did not increase DNA damage, the exposure to AR2 and AR10 caused a significant increase in the occurrence of DNA damage. In conclusion, this study showed that both herbicides applied alone caused effects on C. fluminea; ATZ interfered mostly in biotransformation while RD interfered mainly in antioxidant defenses leading to lipid peroxidation. The herbicides mixture showed antagonistic effects on the gills EROD and on lipid peroxidation in gills and digestive gland and synergistic effects on the gills MXR and on DNA damage in the hemocytes.
