Recent Advances in Understanding the Influence of Zinc, Copper, and Manganese on the Gastrointestinal Environment of Pigs and Poultry

Abstract

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.

Determination of the Optimal Level of Dietary Zinc for Newly Weaned Pigs: A Dose-Response Study

“…In humans, linear growth is the only recommended functional indicator of Zn requirement, because increased growth as a result of Zn supplementation can only be interpreted as an indication of a pre-existing Zn deficiency [ 28 ]. Similar statements have been made about Zn deficiency in pigs, as it will impair growth performance [ 29 ]. Some dose–response studies have investigated the Zn requirements in weaned pigs [ 30 , 31 ], but these experiments included an acclimatisation period of one to two weeks, and the results can therefore not be used to estimate the Zn requirement immediately PW.…”

“…In the current dose–response study, the aim was to determine the optimal dietary level of Zn (supplemented as zinc oxide; ZnO) for pigs the first three weeks PW, and the endpoints were feed intake, growth performance, serum Zn status, faecal scores, blood biomarkers of intestinal integrity (D-lactate and diamine oxidase activity [DAO]) and faecal microbial composition. Especially the latter was intended to illuminate when and if supra-nutritional levels of dietary Zn were supplied, since Zn-induced modifications of the gut microbial community have been used to distinguish between nutritional and pharmacological effects [ 29 ]. It was hypothesised that 150 mg Zn/kg diet is insufficient to provide newly weaned pigs with the currently recommended 46.8 mg Zn/day due to low feed intake, but also that the optimal Zn supply immediately PW may be substantially higher than what NRC recommendations currently indicate.…”

Importance of Zinc Nanoparticles for the Intestinal Microbiome of Weaned Piglets

“…Zn also inhibits NADPH oxidases, resulting in reduced formation of reacive oxygen species (ROS) ( 21 ). Several systematic reviews of Zn's role in the mammalian organism have been undertaken ( 22 – 24 ). However, new findings in this field are still developing.…”

Relative Bioavailability of Trace Minerals in Production Animal Nutrition: A Review

“…Often, wide safety margins for mineral levels are permitted in feed formulation in an attempt to counteract dietary antagonists or to allow the mineral to act as a growth promoter [ 34 , 35 ]. Legal limitations can vary between regions with some permitting higher levels of supplementation than others [ 36 ].…”

“…Post-weaning diarrhoea (PWD) due to Escherichia coli has a significant economic impact on pig production and is one of the main reasons pharmacological levels of ZnO were used. Recent reviews on trace mineral supplementation and its effect on the intestinal health of monogastrics have highlighted the importance of precise supplementation to maintain nutritional benefits but minimise environmental impact [ 35 , 318 ]. Organic forms of Zn can be used as part of a nutritional solution improving gut integrity/improved growth and performance thereby reducing the need for the oxide form.…”