Future of Zinc Oxide in piglet diets: Feedback from the Zero Zinc Summit

Feedback from the Zero Zinc Summit 2019, Denmark

By WJ Steyn, SwiNE Nutrition Management

Feeding therapeutic levels of Zinc as Zinc Oxide (ZnO) has been a common practice in most countries in the world, with the exception of the Netherlands where this was actually never allowed.

Improvements in piglet weight gain and reduction in gastrointestinal upsets are the most prominent effects. The exact mechanism behind the mode of action of therapeutic Zn is still not fully understood, and was mentioned a few times during the Zero Zinc Summit.

It was already shown in the early 1980’s that feeding high levels of Zinc (2500 mg/kg) as Zinc Oxide, resulted in the lowest incidence of post weaning diarrhoea.

The basic nutritional requirement for Zn ranges from 100 to 150 mg/kg during the same phase. Thus indicating that we are feeding more than 20 times more Zn to the piglets to cover their basic needs.

The European commission (EC) has voted in favour of the ban on the use of therapeutic Zn in piglet diets. The decision was made on June 2017 and the EC has given the EU member countries five years (until 2022) to phase it out of all piglet diets. Thus by 1 July 2022 the use of therapeutic Zn in pigs will be prohibited.

The Zero Zinc Summit was held in Copenhagen, Denmark late June this year, with more than 400 delegates participating from all over the world. The objective of the Zero Zinc Summit was to present and share ways to reduce the use of therapeutic levels of Zinc and other minerals in piglet diets, currently used as a tool to control post-weaning diarrhoea.

The summit was also an opportunity for suppliers of potential alternative to Zinc Oxide to present their research and findings. 

My take home message from the summit was that it is possible to reduce the amount of Zinc we use in our piglet diets, but it would require a mind-set change and a completely different approach in how we formulate piglet diets.

Alternatives discussed

There is probably not a single feed additive, which can replace ZnO. Many feed additives share several of the modes of action by which ZnO can prevent diarrhoea. The ideal feed additive for enhancing gut health is probably a combination or cocktail of agents with antibacterial and immunomodulatory effects targeting the specific agents as infection progresses. Starting nutritional interventions, as early as with the sow and pre-weaned piglet, may be necessary in order to efficiently influence the interaction between the micro-biota and the host.

Most single bullet approaches and products that were compared to high levels of ZnO during the summit, could not match the benefits ZnO has to offer.  Some got close, but I believe to be able to achieve similar results it would most likely need to be a combination of feed formulation, management strategies, health and the correct blend of feed additives to reduce ZnO usage. For more detail on the alternatives and short summary of the presentations visit Pig Progress, Zero Zinc Summit: How to replace ZnO? Link https://www.pigprogress.net/Health/Articles/2019/7/Zero-Zinc-Summit-How-to-replace-ZnO-447733E/

Why reduce ZnO in piglet diets if it is working so well?

Across the globe, swine producers face increasing pressure to improve their sustainability, especially for nutrient management of manure and land use. By 2050 we will be overusing the earth’s resources with more than 400 % according to DSM. The message was that we need to consider what we use in our diets as this will affect the earth and available resources going forward. The main motivations behind the reduction of Zn (and other minerals) in piglet diets can be seen below:

• Pigs and their microbes are developing Zn resistance (Stark et. al., 2013),

• High Zn usage is also linked to antibiotic resistance.

• E.coli resistance (Bednor, 2013)

• Tetracycline resistance (Vahjen 2015 and 2017)

• Environmental and soil pollution. Zn and Cu found in high levels in manure, thus resulting in high levels in soil.

• A negative impact on gram positive microbes, reducing the good bacteria (Lactobacilli, Lactic acid bacteria).

• It is also seen as our social responsibility to start looking for better and more environmental friendlier ways to feed our livestock.

Can I just take ZnO out of my diet?

Diarrhoea and diarrhoea causing bacteria are present and by just reducing the levels or removing ZnO from the diets will result in a disaster. In countries such as South Africa where antibiotic use is an easy alternative, the removals of ZnO without making any other dietary and management adjustments will result in even more gastro intestinal tract problems, and an even further increase in antibiotic usage. This defeats the purpose of reducing Zn in the first place.

Thus lowering the ZnO levels without making the right or necessary changes will only increase antibiotic usage, as this is still the first line of defence in most cases for diarrhoea treatment.

A different approach

Early stage nursery diets are mainly formulated today on least cost principles and in most cases include high levels of ZnO, CuS and in-feed antibiotics to enhance piglet performance. Our targets or goals today for the nursery stage are production driven. Weight out, growth rate, FCR and feed cost per piglet produced are some of the production parameters taken into account. These are all good targets to aim for, but would be a challenge to maximise or match the current levels achieved with diets containing none of these aids. Bikker, 2018 showed  improvements of 28% in gain, 23% in feed intake and 11% in FCR, with feeding higher ZnO diets (2500 mg/kg) compared to diets containing only 100 mg/mg of ZnO.

A different approach is needed in piglet diet formulation and piglet management if we would need to comply with the changing environment in piglet nutrition. A few points to consider:

The first stage piglet diets should not be purely based on least cost formulation. It should not only be about costs, but should be about what is the best way to assist the piglet through this stressful period.

Early stage piglet diets only represent 2-3 % of all feed produced and used in a piggery; but it is key to ensure optimal performance and health of the pigs until the end of their lives.

Growth rate in the nursery barn is secondary to good gut and overall health. Get them started well, and then start pushing to market.

Fibre is not your enemy. Fibre has a bad name for reducing FCR and growth, but fibre plays a key role in establishing and improving gastrointestinal tract functionality. During the summit, Suckling (2019) showed the advantage of using 4% wheat bran in piglets diets compared to high ZnO levels.

We need to realise that performance will decrease (at least in the first few weeks after weaning).

Lowering antibiotic and ZnO usage will reduce growth performance in the nursery barns, but it is possible to catch up later in life, if piglets had a strong and healthy start.

Diets changes and interventions are needed if we are going to pull this off.

Lower crude protein levels in diets

More digestible ingredients need to be used in piglet diets. To increase the digestibility of ingredients, cooking and fermenting cereals is an option.

Feed additives like organic acids, probiotics, and yeast will play an important part.

More bioavailable types of mineral sources need to be used in diets.

Organic forms and also micronised minerals are options.

Maternal nutritional interventions by feeding the sow to benefit the piglet also need to be considered.

The health status of farms is also important. It is easier to work in an environment where the bacterial, disease load or pressure is lower.

Weaning age is most likely to increase. It is easier to work with a piglet at weaning of >7 kg than 5 kg. The older you wean the easier it becomes.

Coarse wheat bran (1088 micron) at an inclusion of 4% has been shown to reduce post-weaning diarrhoea in piglets in the absence of zinc oxide. Inclusion of high levels of Zn significantly improved piglet performance.

Addition of wheat bran to the diet resulted in a significant improvement in piglet growth and FCR when included in the 150 ppm Zn diet suggesting that wheat bran inclusion in piglet diets may be useful to maintain piglet performance in the absence of high levels of Zn.

Final remarks

The early development of piglets depends directly on their health and nutrition, and is key to their lifetime performance. Intestinal challenges are the main cause of performance losses during the post-weaning period, which will consequently translate into critical economic losses accumulated throughout the pig’s life.

In terms of the big effort made to reduce antibiotics in animal husbandry and the upcoming ban of ZnO in pharmacological effective dosages the pig-producing sector needs new concepts to stabilise gastrointestinal health and therefore combat post-weaning diarrhoea. Currently a lot of effort is put into research on finding alternatives to high levels zinc oxide as a mean to reduce post-weaning diarrhoea.