Iron Supplementation in Nursing Piglets

By Dr. Christo Fick and Dr. Nadia de Beer for Virbac

Agri FARMACY Professional Services Inc

According to the Golden Circle model it is important in any decision-making role to ask the following questions in order to have a purposeful outcome. WHY, HOW and WHAT?

This article will focus WHAT is anaemia in nursing piglets, HOW do we measure if piglets are anaemic and WHY is it important to know and measure?

Iron deficiency anaemia in piglets

Anaemia occurs when the piglet has a decreased level of haemoglobin in the red blood cells.  The body needs iron to make haemoglobin (iron-carrying protein haemoglobin in the red blood cells), therefore without enough iron, the red blood cells can not carry enough oxygen to the body of the piglet.

Piglets are naturally born with a limited supply of iron of about 50 mg (Venn et al). Pigs that are born in the wild will naturally find supplementation through their diet for example by consuming iron bearing soils. Piglets in intensive production systems do not have access to natural occurring iron. The sow’s milk which is limited to 1mg of iron in her milk per day is a poor source of iron. With an increase in litter size, the piglets from modern prolific breeding sows are even more compromised. Only later in their life (at around 10 days of age) do they have access to creep feed. It has also been noted that the fastest growing piglets have the highest risk of developing iron deficiency anaemia because they are often on an all-milk diet (good source of nutrients but not iron) and they do not readily consume creep feed. They are the dominant animals in the pecking order system and piglets have a high preference for sow’s milk over any other offerings.

Iron deficiency anaemia can manifest itself in two different forms namely, sub-clinical and clinical anaemia with the latter referred to as full scale iron deficiency anaemia.

Measuring haemoglobin levels

A hand device called HemoCue® is available that is used to test piglet haemoglobin levels. It is an easy and relatively inexpensive test that can be conducted on farm. It gives a quick accurate measurement of the blood haemoglobin levels.

Most piglets are born with a normal amount of haemoglobin but with the piglets’ genetic potential these days to rapidly grow on an only milk diet they can quickly move into a state of subclinical anaemia or a full-scale iron deficiency anaemia. Other factors like stress for example can also play a role in causing anaemia in piglets by inhibiting the build-up or by degrading haemoglobin.

Haemoglobin levels
Clinical picture HB levels in g/L
Optimal >110
Sub clinical anaemia 110-90
Clinical anaemia <90


Sub clinical anaemia

It is very difficult to diagnose sub clinical anaemia on clinical signs alone.

Some of the signs one can look for is a poor growth rate and pale mucous membranes but the most accurate diagnosis comes from measuring the haemoglobin levels in the blood of the piglet. Sub-clinical levels are between of 110-90 g/L.

Clinical anaemia

The most common symptom is that of lethargic piglets. They are easy to notice as they look tired, do not play with pen mates and are reluctant to move around. They are also pale in colour when compared to their litter mates.

Severe cases will present with a respiratory distress and increased heart rate. Some cases also may present with scours due to an impaired immune system.

Iron Gap

The so-called iron gap can be determined mathematically. According to Pharmacosmos, based on their on mathematical model, the birth weight of about 1.4 kg and a normal weaning weight of 7 kg is determined. Each farm has its own values. The theoretical iron need of 67 mg/kg weight gain is calculated to estimate the iron need in the nursing phase.  The natural source of iron is approximately 80 mg, made up from the iron available at birth plus that which is offered, however marginal, from the sow’s milk. This can be subtracted from the additional iron needed to prevent the iron gap.

A pig producer should preferably want to treat the piglets in this state before it progresses into a full state of clinical anaemia. At that time the piglet’s health has suffered severely and the chances of saving the piglet has decreased dramatically.

WHY is anaemia so important?

According to Prof. Robert Friendship from University of Guelph, Canada: “That anaemia in piglets poses a serious threat to both animal welfare and profits and is not new to swine oducers. The problem is that many go about in the mistaken belief that the risk of anaemia has been eliminated with the administration of 200 mg supplemental iron to the piglets when, in reality, what we see is that the increased productivity of modern swine production has caused increased iron needs.”

For an improved growth rate and an optimal development of the immune system of the piglet, haemoglobin and myoglobin are two proteins that play a very important role. For them to be at their optimal levels they need iron to be at adequate levels within the piglet.

According to a clinical study (Bhattarai, 2015) an increase of 10g/l of haemoglobin at weaning led to a 17.2 g/day weight gain increase in the 3 weeks post weaning. Olsen, 2018 showed that a second dose of iron given at day 5-7 after birth lead to a 1.4 kg increase live weight at 18 weeks post weaning.

Iron is vital metal for the proliferation of cells including those of the immune system, thus the importance of anaemia in piglets cannot be underestimated. This aspect is very important since piglets receive numerous vaccinations in the early stages of their life.

Numerous farm trials that have been conducted by Agri FARMACY SA Professional Services practice showed interesting and varied results. The situation on each farm was subtle and different and it was difficult to determine a general pattern or guideline. In other words, no ‘one size fits all’. Factors that played a role was the haemoglobin status of the sow at the time of farrowing. We found that on some units that many sows were in fact sub-clinically anaemic. There were individually sub-clinical sows on so-called normal herds and then we found herds where we could classify the whole breeding herd as sub-optimal. What was interesting is that on some herds many sows became sub-clinical 5 to 7 days post farrowing. Their individual litters were in a varied state of sub-clinical to clinical anaemia.

Attempts to treat the specific sow herds to prevent sow anaemia was disappointing and expensive and in our opinion was not cost effective.

The reasons for anaemia in sow herds was considered. We found poor water quality to be a consistent factor. Gastric ulcers were considered and is difficult to diagnose. Chronic ileitis in younger breeding animals was considered and Mycoplasma suis was also considered. The latter also difficult to diagnose.

It is our opinion that piglet treatment is cost effective and that a clinical examination is required to determine the best practice on very farm.

Rather than treating cases of anaemia, a preventive measure should rather be followed. This is done by supplementing the piglets at the correct time with additional iron.

Methods of supplementation

There are several practices that can be used to supply piglets with additional iron sources: parenteral iron injection, oral supplementation, or iron from the environment.

Where parenteral iron injection is by far the best choice as it is the practice that delivers the best results in the form of administering the correct amount of iron at the correct time. It also delivers the best form of absorption and is the most cost effective as well being the least labour intensive.

A typical single 200 mg iron supplement in the piglets’ first week is not enough. A two-shot iron supplementation protocol might be effective way of replenishing iron stores in the piglet body by closing the iron gap. The timing of first and second iron injection is critical and needs to be in line with piggery specific iron gap profile.

It is recommended that the administration of more than 200 mg iron per piglet just before weaning should be done under the supervision of a consulting veterinarian.

By working closely with your veterinarian, you can precisely try do identify where the “iron gap” occurs on your piggery. Iron supplementation programs can be developed accordingly.

Sub-clinical anaemia might be one of the most costly, well-hidden problems on a piggery that production teams fail to recognise or acknowledge.


  • Bhattarai, S., & Nielsen, J. P. (2015). Association between hematological status at weaning and weight gain post-weaning in piglets. Livestock Science, 182, 64-68.
  • Bhattarai, S., & Nielsen, J. P. (2015). Association between hematological status at weaning and weight gain post-weaning in piglets. Livestock Science, 182, 64-68.
  • Venn J.A.J., McCance R.A., Widdowson E.M. (1947): Iron metabolism in piglet anaemia. Journal of Comparative Pathology, 57, 314–325
  • De Sousa M., Breedvelt F., Dynesius-Trentham R.D., Trentham D., Lum J. (1988): Iron, iron-binding proteins and immune system cells. Annals of the New York Academy Sciences, 526, 310–322.
  • Look out for the iron gap by Anne Mette Strunz Hanl, DVM, Denemark (
  • Uniferon® Best Practice Recommendation Iron Gap
  • Recognising and treating pig diseases. Michael. R. Muirhead and Thomas J.L Alexander
  • Discussions between the partners of Agri FARMACY SA Professional Services Inc.

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