Source, solubility and levels fed matter
~ by Alice Hibbert, Programme Manager Trace Minerals Selko,
Introduction
Researchers found that adding hydroxychloride copper (IntelliBond®) to swine diets could help improve growth performance and reduce negative interactions between copper and added vitamins or enzymes. The use of high levels of copper also was found to limit the overgrowth of unwanted bacteria helping to manage gut health, increasing average daily gain (ADG) throughout production and improving hot carcass weight.
The primary goal of adding trace minerals to swine diets is to fulfil animals’ nutritional requirements. Feeding the optimal amount of trace mineral allows animals to maintain positive homeostasis supports good performance. Trace minerals are required for important functions, such as optimal fertility and immunity, and are therefore essential nutrients to ensure optimal growth and performance. A poorly balanced trace mineral supply can have an increasingly negative influence on performance, etc. It is important to remember that the animal will choose how it utilises the nutrients it takes in, and therefore if there is a trace mineral deficiency, the animal’s system will divert the remaining supply to the ‘most vital’ body functions. Therefore, the first visual signs of a deficiency may be ‘less vital’ functions such as growth, reproductive performance and skin integrity. When supplementing diets with trace minerals, the source matters.
Mineral supplementation has evolved since the use of oxide-based trace minerals in the 1930s. Sulphate-based trace minerals were introduced in the 1940s followed by the development of organic trace minerals in the 1970s. Organic trace minerals improved mineral bioavailability and effectiveness but remained expensive. As it was not always economically viable to replace all sulphate and oxide forms, many producers only partially replaced the use of inorganic mineral sources. Hydroxy trace minerals, developed in the 1990s, provide a concentrated, bioavailable trace mineral source, and offer a way to entirely replace the use of inorganic mineral sources.
Source of Copper Affects Vitamin Stability
Copper is a catalyst of several important enzymatic reactions taking part in the antioxidant defence of the body, such as Superoxide Dismutase (SOD). The nutrient supports the functioning of macrophages focused on combating infectious elements, and helps with the formation of collagen and elastin. However, the source of the copper added to diets can influence both its availability to the animal and the availability of other dietary nutrients. More soluble trace mineral sources (sulfates based trace minerals) can have a negative influence on vitamin stability in feed.
It is well established in the literature that retention of feed vitamins (such as E, A and certain B complex vitamins) over time will vary based on what type of trace minerals were included. For example, feeds containing chelated trace mineral sources retain more vitamin activity over six months, compared to sulphates. A trial carried out in 2010 examined the stability of vitamin E in feeds supplemented with no trace mineral, or 200ppm of either hydroxy copper or copper sulphate. Researchers found that during a 41-day window, feeds with no supplementation or supplementation with hydroxy-copper maintained similar amounts of vitamin E. Feed with copper sulphate lost about 69% of the vitamin by the end of the trial. Hydroxy copper does not interact with vitamins in feed, meaning more vitamins are left for the animal to use. Similarly, when chicks received diets supplemented with 100, 150 or 200ppm copper sulphate or hydroxy copper and vitamin E, the amount of vitamin E found in birds’ blood plasma was 11% higher for birds eating feeds with hydroxy copper.
Mineral Source and Phytase Function
Trace mineral copper source can alter how added enzymes, like phytase, function in diets. In an in vitro study completed in 2006, researchers examined the interaction between supplemental copper and phytase in feeds. The researchers looked at the use of copper citrate, copper chloride, organic copper or copper lysine, copper sulphate and hydroxy copper at levels including 0, 62.5, 125, 250 or 500ppm. As the amount of copper added to the feed increased, the amount of phosphorous hydrolysis (the amount of phosphorus released from the Phytate molecule) in the diet fell. However, the most extreme negative reactions followed the combination of phytase and copper chloride, copper sulphate and copper citrate. If a high level of one of these types of trace mineral is included in the diet, significantly less Phosphorus could be liberated from the phytate by the activity of the phytase enzyme. This is because Phytate has a high affinity for the soluble trace mineral ions (e.g. Cu2+) which easily dissociate from their ligands (e.g. sulphate) and bind to the phytate, blocking phytase activity. Phytase function remained highest when hydroxy copper was supplemented. Therefore, the use of a trace mineral source which remains insoluble in feed can minimise interference with phytase function.
Copper in Grow-finish Pig Diets
A trial at Kansas State University, tracked 1,143 swine for 111 days. Diets included a negative control and experimental diets comprised of the negative control feed with 75 or 150ppm copper from a Copper sulphate or hydroxy Copper source. When 75ppm Copper was added to swine diets, pigs receiving the hydroxy Copper gained more weight than those on the Copper sulphate diet. The difference seemed to peak when pigs reached about 90 kg. Pigs seemed to stop gaining at that point regardless of the type of Copper used in the diet. When 150ppm Copper was added to diets, pigs on the hydroxy Copper supplement continued to gain weight for longer (to around 110kg) through the production cycle than those fed sulphate trace minerals. This suggests that extra benefits for growth can be seen if high levels of Copper are fed from a hydroxy source compared to sulphate through the entire grow-finish period. Comparing pigs receiving diets with 150ppm from hydroxy copper and those on a Copper sulphate diet, there was a 2.1kg improvement seen in hydroxy-supplemented pigs.
Meta-analysis of Copper Trials in Swine
Trials conducted at Kansas State University sought to evaluate the influence of adding a high level of hydroxy Copper to the diets of grow-finish pigs compared to swine receiving nutritional levels of the mineral. Pigs were tracked for growth performance and carcass characteristics. Eight trials from 2013-2018 involved 6,790 swine. Diets included hydroxy Copper at high levels – 75, 150 or 200ppm copper, and the control groups were fed nutritional levels (13-20ppm) of copper from a basal premix.
Findings
The findings include:
- Looking at the hot carcass weight of pigs from individual studies based on their diet found that use of high levels of Copper increased weight in almost every trial. Increases ranged from +0.04 to +3.2kg.
- Overall, hot carcass weight for pigs on the high-Copper diets saw a significant improvement as weight grew by 1.31kg compared to results from swine receiving nutritional levels of the trace mineral.
- ADG increased during both the grower and finisher phases and average daily feed intake also improved during the grower phase. * Pigs receiving higher levels of copper saw bodyweight improvement during the grower and finisher phases.
- Swine on the high-Copper diets saw significant improvement to ADG and average daily feed intake. Swine performance showed benefits in both the grower and finisher phases.
- Improvements in hot carcass weight and growth performance occurred regardless of season.
- Adding high levels of Copper to swine diets increases feeding costs, but the additional weight can provide more benefit depending on the price per kilogram. In an economic analysis, the gain in improvement over feed cost was $0.56 (USD) per pig, showing a strong benefit to farm profitability of supplementing high levels of hydroxy copper source.
Considerations in Selecting Copper Source
Adding high levels of Copper to swine diets can bring weight and carcass improvement through the grow-finish phase and may provide additional economic returns to producers by managing the microbial population on the GIT, as well as impacting nutrient digestibility. Using a hydroxy Copper, with low solubility in feed means the trace mineral source will not interfere with vitamin stability, or reduce the effectiveness of added enzymes, like phytase. Instead, the mineral will be available to be absorbed in the small intestine, supporting the many important functions within the animal which rely on trace minerals.
