In 2017, the European Commission outlined its intention to ban the use of zinc oxide for therapeutic use in pig diets.
Typically included at over 2,000 parts per million (ppm) in diets, zinc oxide has been key to preventing post-weaning diarrhoea in pigs. Going forward, it can still be used as a feed additive, but at a much lower inclusion rate of 150ppm.
The ban on therapeutic use has been in place from June 2022. However, there is a two-year withdrawal period on any products manufactured before this date, which effectively means it will be the spring of 2024 before it must be removed from diets.
According to Dr Marian Scott, a pig nutritionist with Devenish Nutrition, a lot of progress has been made since the ban came into force and around 80% of diets now sold by the company have the zinc supplement removed.
“The farmers who have embraced it have been successful.
There have been challenges along the way which have varied from farm to farm, so a collaborative approach between farmers, nutritionists and vets has proven to be the best approach when trying to manage the removal of zinc,” she says.
Her advice to those who might still be hesitant is to make use of the time available and not end up in a situation where zinc has to be taken out of the diet next spring with no knowledge of the potential implications on farm.
“If we start working on this now, we can do so on a sub population of pigs which will allow us to figure out in a controlled manner if there are likely to be any issues. By acting now, it means that if issues do arise we have time to understand what happened and to go again before zinc is totally gone.”
Nutrition companies like Devenish have been working on the removal of zinc oxide for many years, trying to understand what it does, whether in terms of increasing nutrient digestibility or improving the immune system and gut microbiome in young pigs.
When removing zinc oxide from piglet diets, some nutritionists advise lowering crude protein and increasing fibre, with the aim to reduce the passage of excess protein in the hind gut which can exacerbate post-weaning diarrhoea.
However, lower protein and higher fibre can have a negative impact on growth rate.
In the case of Devenish, it has developed its own range of specialist EnteriMax piglet diets, with research showing that it is possible to match the performance of traditional feeds containing zinc oxide (Table 1).
In practice, removing zinc oxide is a step-by-step process on farm over a period of a few months, says Marian, normally starting with the link diet and then looking at reducing levels in creep feed.
The key is gut development, and to condition the animal for the post-weaning phase the target should be to get 400g of creep into piglets pre-weaning.
“You have to try to introduce creep as early as possible. From seven days of age, put a very small amount into creep dishes at that point. Offer creep in small amounts and keep it fresh,” she advises.
Good management is also vital, including best practice around cleanliness in first stage accommodation, keeping temperature and ventilation at optimal levels and ensuring drinkers have the correct flow rate (450ml per minute).
The pig industry continues to set the benchmark when it comes to genetic advances.
For example, in the last five years, producers in Northern Ireland have increased numbers born alive by 15%, to an average of around 16.
Those higher litter sizes bring various challenges, including more low birth weight pigs (under 1kg) and increased likelihood the sow will not have enough colostrum to feed the entire litter.
These factors add an extra level of complexity as zinc is removed from piglet diets.
To keep pace with genetic advances, feed companies are continually trialling new products.
Devenish has developed a supplement (ColfaPig) to be fed to both dry and lactating sows, which aims to provide a mix of encapsulated short- and medium-chain fatty acids.
“If we can optimise the ratio of fatty acids then we are driving the potential of the animal’s own system,” suggests Marian.
Ultimately, the aim is to develop a nutritional strategy to relieve oxidative stress in sows during late pregnancy and lactation.
As an industry, we are adding litter size, so there are more small pigs – they are less mature; have lower energy reserves
Oxidative stress damages proteins and lipids in the animal, negatively impacting performance – it is a process which is brought on by the metabolic burden placed on modern high-performing sows.
As shown in Tables 2 and 3, feeding the fatty acid supplement resulted in the productivity of the sow being improved, with more embryos surviving, higher weaning weights and better colostrum quality.
“As an industry, we are adding litter size, so there are more small pigs – they are less mature; have lower energy reserves – we need to try to drive them on as quickly as possible. As nutritionists, we are constantly working at this,” says Marian.