Zinc, copper, and manganese are prominent essential trace (or micro) minerals, being required in small, but adequate, amounts by pigs and poultry for normal biological functioning. Feed is a source of trace minerals for pigs and poultry but variable bioavailability in typical feed ingredients means that supplementation with low-cost oxides and sulphates has become common practice. Such trace mineral supplementation often provides significant ‘safety margins’, while copper and zinc have been supplemented at supra-nutritional (or pharmacological) levels to improve health and/or growth performance. Regulatory mechanisms ensure that much of this oversupply is excreted by the host into the environment, which can be toxic to plants and microorganisms or promote antimicrobial resistance in microbes, and thus supplying trace minerals more precisely to pigs and poultry is necessary. The gastrointestinal tract is thus central to the maintenance of trace mineral homeostasis and the provision of supra-nutritional or pharmacological levels is associated with modification of the gut environment, such as the microbiome. This review, therefore, considers recent advances in understanding the influence of zinc, copper, and manganese on the gastrointestinal environment of pigs and poultry, including more novel, alternative sources seeking to maintain supra-nutritional benefits with minimal environmental impact.

Supplementation of pharmacological levels of ZnO (3000 ppm) is widely used for prevention and treatment of diarrhea in weaning piglets and to improve their performance. However, this practice has raised concerns about environmental impact, antimicrobial resistance and nutritional interactions. In this study we compared graded amounts of regular ZnO to equivalent levels of potentiated ZnO (HiZox), added to the piglet’s diets. Our aim was to assess possible advantages of different Zn sources as well as a reduction potential regarding the supplemented dose. Therefore, 1440 piglets (initial BW 10.1 ± 1.55 kg) were randomly allotted to 12 dietary treatments: supplementation of 150, 300, 600, 900, 1500 and 3000 ppm of Zn from regular ZnO or equivalent from HiZox. From day 1 to day 14, piglets were fed dietary treatments accordingly; from day 15 to day 28 all groups received HiZox at 150 ppm. Performance was recorded on d 1, 14 and 28 on trial.The highest (P < 0.001) ADG was observed for piglets fed HiZox at 3000 ppm (247 g/d), while HiZox at 900 ppm and regular ZnO at 3000 ppm presented the same ADG values. The subsequent 14-day levelling to 150 ppm of HiZox led on average to similar body weight gains (ZnO: 7.05 kg; HiZox: 6.93 kg). ADFI increased (P < 0.001) in the first 14 d of trial with increasing Zn levels for both sources. Comparison of ZnO at 3000 ppm and HiZox at 900 ppm showed similar effects on improving fecal consistency during the first two weeks after weaning, which may be due to the more effective surface specific area of HiZox than regular ZnO. In conclusion, HiZox at 900 ppm can be used for improving growth performance and fecal consistency during the first two weeks after weaning as an alternative to the pharmacological level of regular ZnO.