How iron injecting outdoor piglets increases weaning weight

Injecting outdoor piglets with iron could boost weaning weights and offer a 10:1 return on investment.

Injecting newborn piglets with iron may be a routine procedure on most indoor units, but for outdoors herds, it is often perceived that sufficient iron is obtained from the soil, making supplementation quite rare.

However, a recent trial revealed iron could boost weaning weights significantly on outdoor units, as a trial at Basil Baird’s farm in West Sussex exposed. Here, weaning weights were increased by 0.6kg in some months, with an average weaning weight improvement of 0.26kg.

And it was only after some initial work conducted by farm vet Richard Pearson, George Vet Group, Wiltshire, that Mr Baird and farm manager Bruce Golding decided to conduct a trial with Mr Pearson and BPEX on their 1800 sow outdoor unit.

Mr Pearson says what struck him was the fact that out of 30 of the outdoor herds the practice looks after, only one was injecting piglets with iron.

“That was one of the major reasons for taking on this project, as there is a common perception that iron from soil is enough to meet piglets’ needs.”

However, as Mr Pearson explains, outdoor pigs are now more prolific, producing larger litters with piglets that also have a high growth potential.

“When you have got this growth potential then they have more blood to manufacture and iron is an important constituent of this. So piglets often need an external source of iron aside from the sow’s milk,” he says.

It is thought piglets require about 10mg of iron a day for maintenance and growth, whereas sow’s milk only provides 1mg iron/litre.

The trial at Mr Baird’s farm involved splitting the 1800-sow herd in two, with one group treated and the other used as a control and then rotated on a four-weekly basis. The treated piglets received 200mg of elemental iron within 48 hours of birth. Piglets were then weighed at weaning.

The results were significant, with the iron-treated piglets heavier than those untreated, explains Mr Pearson.

“Weaning weight was the main parameter measured and the mean weaning weight was 7.37kg for the treated group and 7.11kg for the control group, an average of 0.26kg difference,” he says.

“Blood from treated piglets also had more haemoglobin and more red blood cells, which carry more oxygen and as a result weaning weights increased due to improved blood parameters,” explains Mr Pearson.

However, improvements in weights peaked at 0.6kg with some level of seasonality involved, he adds.

“Batches born in summer showed poorer results for weaning weights compared to those born earlier in the year and it’s likely the behaviour of sows and piglets were responsible for this.”

Mr Pearson believes the reason why iron had more of an affect in the colder months was because sows and piglets spent longer inside the arc, whereas in the warmer weather and longer day lengths sows spent extended periods of time wallowing, so often came back to suckle litters with teats covered in soil.

“The piglets obviously consumed relatively large amounts of soil and their iron intake was therefore higher.”

And when you consider a 0.5kg increase in weaning weight is worth five days less to slaughter and an extra margin for every slaughter pig of £5-7, plus considering the cost of a shot of iron is less than 10p a pig, it’s no wonder farm manager Mr Golding is continuing to treat piglets with iron.

“Iron injecting piglets gives a ROI of 10:1, it is cost effective to do it and isn’t any more labour intensive as we are already handling the piglets during this period anyway.

“The soil at this farm wasn’t low in iron as we are on medium to light land over gravel, which reinforces the benefits this could possibly have in herds with lower iron contents,” adds Mr Golding.

Mr Pearson also stresses that even when soils have been tested for iron content, interpreting the information can be tricky.

“Because iron can be bound up with different elements it can be hard to determine actual levels within the soil.

That’s why it’s important that individual producers speak with their vet before considering intervention.

There is no excuse when you are an outdoor producer for not maximising production efficiency, especially given the increase in feed prices.”