Is iron the missing link for robust weaners?

As for many ingredients, a proper balance is necessary when supplying iron to newly weaned piglets. Iron is essential for piglets at this stage of life, yet too much of it can lead to health issues. How can producers make sure that the young weaners get exactly the right amounts to make them thrive?


I 2 1.3 1

ron is an essential trace element playing key roles in oxy- gen transport, cellular and whole-body energetics, im- mune function and as an antioxidant. Within the body, iron is primarily found in the haemoglobin of the red

blood cells. However, iron also plays a key role in animal health, particularly at the intestinal level where the host and microbes – including pathogens – compete for iron. It has been known for a long time that when iron intake in weaned pigs is high, microbes in the intestine, including pathogenic bacteria, multiply excessively. Less well known is probably the fact that inorganic iron causes damage to the intestinal wall and may also lead to leaky gut. Ultimately, iron overload raises the risk of diarrhoea, may increase the usage of antimi- crobials, can decrease growth performance, compromises an- imal well-being and, in severe cases, may increase mortality.

3 Figure 1 - Days with diarrhoea on per pen basis.

Fe-AA chelate* Fe sulphate 2.0

If iron intake is to be controlled, then the logical place to start is looking at how much iron is in the feed. The level of iron in a weaner diet without any supplemental iron is already quite high and ranges from 100 to 200 ppm depending on ingredi- ent composition. Feedstuffs high in iron include phosphates, limestone, soybean meal and wheat bran. In the past, when phytase was not added to swine diets, the availability of background iron was rather low. However, sub- stantial amounts of iron in cereals and soybean meal are bound to phytate. Thus adding phytase to the diet, in particu- lar when using super-dosing levels, not only improves the availability of phosphorus but also increases the amount of iron available to both the pig and the microbes that are har- boured in the pig’s intestine. On top of background iron, sup- plementing between 100 and 150 ppm iron is common throughout the industry, resulting in a total iron level of 200 to 350 ppm.


* Availa Fe, Zinpro Performance Minerals. Diarrhoea, days

Source: Grela et al., 2005. 32

Weaned pigs absorb inorganic iron poorly The high background iron level in the diet and poor absorp- tion of inorganic iron result in large amounts of unabsorbed iron in the intestinal lumen of pigs within the first few weeks after weaning. It is well known that micro-organisms such as bacteria require iron to grow. Not only does iron affect growth of microbes, it also increases the virulence of patho- genic bacteria such as Escherichia coli and Salmonella Typhi- murium that are present in the intestine. Consequently add- ing inorganic iron to weaner diets is a significant risk factor for enteric diseases. The mitigation of this risk is critical to successfully manage health challenges of piglets after wean- ing and maximise growth rate. It will become even more criti- cal as, in the very near future, high levels of zinc oxide will be banned and the use of antimicrobials in pig production minimised. The form of supplemental iron is important, as different forms will vary in several key attributes that together determine their value to, and effectiveness within, the animal. Availa Fe (Zinpro) is a 1:1 iron-amino acid chelate that uses a specific absorption pathway – the amino acid transporter. It is water soluble, is stable at the low pH found in the stomach, is not affected by antagonists, is absorbed more efficiently and is metabolised differently by the animal. The way the mineral is absorbed, combined with the fact that it is not degraded in the

▶ PIG PROGRESS | Volume 37, No. 7, 2021


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