Confirming the presence of selected antibiotics and steroids in Norwegian biogas digestate

Farms utilizing sewage sludge and manure in their agronomic plant production are recognized as potential hotspots for environmental release of antibiotics and the resulting promotion of antibiotic resistance. As part of the circular economy, the use of biogas digestates for soil fertilizing is steadily increasing, but their potential contribution to the spreading of pharmaceutical residues is largely unknown. Digestates can be produced from a variety of biowaste resources, including sewage sludge, manure, food waste, and fish ensilage. We developed a method for the detection of 17 antibiotics and 2 steroid hormones and applied the method to detect pharmaceutical residues in digestates from most municipal biogas plants in Norway, covering a variety of feedstocks. The detection frequency and measured levels were overall low for most compounds, except a few incidents which cause concern. Specifically, relatively high levels of amoxicillin, penicillin G, ciprofloxacin, and prednisolone were detected in different digestates. Further, ipronidazole was detected in four digestates, although no commercial pharmaceutical products containing ipronidazole are currently registered in Norway. A simplified risk assessment showed a high risk for soil microorganisms and indicates the tendency for antibiotic-resistant bacteria for penicillin G and amoxicillin. For prednisolone and ipronidazole; however, no toxicity data is available for reliable risk assessments.

Chicken Meat Rich in Selenium and Omega-3 Fatty Acids

The concentration of selenium (Se) in food is in many countries too low and the ratio between omega-6 and omega-3 fatty acids too high implying more non-communicable diseases, e.g. cancer, cardiac disease, impaired immune defense, pain, enhanced non-infectious inflammatory response. Meat from animals supplemented with Se and omega-3 fatty acids makes a good source of these nutrients in human nutrition. The worldwide demand for several nutrients is increasing, and food with optimal composition is required. The objective of the present study was to produce chicken meat especially high in Se and with a favorable ratio between omega-6 and omega-3 fatty acids. Sixty newly hatched chickens were fed wheat-based diets containing 40 g rapeseed oil/kg, 10 g linseed oil/kg and varying amounts of selenium enriched yeast for three weeks, resulting in meat with a favorable ratio between omega-6 and omega-3 fatty acids and with selenium concentration ranging from 0.2 to 0.6 mg/kg. This meat would be expected to give health benefits both in prophylactic and therapeutic contexts. It represents a better strategy for increasing the intake of Se and very long chain omega-3 fatty acids at a population basis rather than relying on Se supplements or only on fish resources that are already overexploited and can not cover EPA and DHA requirements (for ensuring optimal health) for more than a fraction of the world’s total population. The meat from the highest Se supplementation treatment groups might be useful for some groups of patients (e.g. with ischemic pain) who might benefit from especially high Se intake.

Effect of dietary selenium and omega-3 fatty acids on muscle composition and quality in broilers

Background

Human health may be improved if dietary intakes of selenium and omega-3 fatty acids are increased. Consumption of broiler meat is increasing, and the meat content of selenium and omega-3 fatty acids are affected by the composition of broiler feed. A two-way analyses of variance was used to study the effect of feed containing omega-3 rich plant oils and selenium enriched yeast on broiler meat composition, antioxidation- and sensory parameters. Four different wheat-based dietary treatments supplemented with 5% rapeseed oil or 4% rapeseed oil plus 1% linseed oil, and either 0.50 mg selenium or 0.84 mg selenium (organic form) per kg diet was fed to newly hatched broilers for 22 days.

Results

The different dietary treatments gave distinct different concentrations of selenium and fatty acids in thigh muscle; one percent linseed oil in the diet increased the concentration of the omega-3 fatty acids 18:3, 20:5 and 22:5, and 0.84 mg selenium per kg diet gave muscle selenium concentration at the same level as is in fish muscle (0.39 mg/kg muscle). The high selenium intake also resulted in increased concentration of the long-chain omega-3 fatty acids EPA (20:5), DPA (22:5) and DHA (22:6), thus it may be speculated if high dietary selenium might have a role in increasing the concentration of EPA, DPA and DHA in tissues after intake of plant oils contning omega-3 fatty acids.

Conclusion

Moderate modifications of broiler feed may give a healthier broiler meat, having increased content of selenium and omega-3 fatty acids. High intakes of selenium (organic form) may increase the concentration of very long-chain omega-3 fatty acids in muscle.