Antioxidants, Immunity and Nutrition

by 5m Editor
13 July 2004, at 12:00am

By Dr Brian Vernon, Park Tonks Ltd. Postweaning Multi-Systemic Wasting Syndrome (PMWS) has been the scourge of British, European and Asian Pig Farmers for a number of years now and significant efforts have been made by the industry to alleviate the devastating consequences of the disease.

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Pigs on ViraMatrix (Vira-Matrix)
Pigs became more active and
alert when put on ViraMatrix
Pigs on ViraMatrix (Vira-Matrix)
Healthy weaners on ViraMatrix
(this farm has PMWS)

These efforts include better management practises such as limiting pig-to-pig contact, reducing stress and increased hygiene along with efforts to ensure growing pigs receive a high quality diet. (See Controlling PMWS for more details on these subjects).

This article provides an overview of how improving the nutritional intake of weaned pigs using ViraMatrix, a supplement high in natural antioxidants, has provided a number of measurable benefits on farms where it has been introduced.


The main criterion in the development of ViraMatrix was to create a feed supplement that would enable feed manufacturers and producers to boost the potential immune enhancing qualities of their feed.

Studies in humans indicate that the role of nutrients such as anti-oxidants and bioflavanoids may be more essential than previously understood, especially in their role of maintaining and improving health and immunity against disease.

Using knowledge gained from the human studies and Park Tonk's expertise in the field of animal nutrition, ViraMatrix was formulated to provide the key dietary elements which were seen as vital to boosting the pigs own defences against disease.

Since July 2001 approaching 255,000 pigs have received ViraMatrix in the UK. The pig farmers that have used ViraMatrix have covered the whole range of units from small to very large.


In the UK it might be expected that the typical piglet mortality level between weaning and 30kg liveweight may be 3-6%. However, on a growing number of pig farms, there has been increased mortality between weaning and 30kg liveweight that has ranged from 15-68%. In most cases this increased mortality has been attributed to the presence of porcine PMWS and/or other associated diseases.

On the farms where ViraMatrix is used mortality figures of pigs from weaning to 30kg liveweight are, in most cases, reported by the farmers to be below 7%. These reductions have been observed on farms where a wide range of other changes have and have not been carried out: such as adopting's 4 Golden rules and Madec's 20 point assessment for example. Certainly, according to reports from farmers who use ViraMatrix, is has had a consistent effect.

These reports from the UK have also been echoed by comments from other pig farmers, both within and outside of the EU, who have used ViraMatrix. ViraMatrix has been trialed and is being used in many of the major pig producing countries across the globe, including France, Germany, Spain, Portugal, Greece, Italy, Poland, Czech Republic, Croatia, Korea and South Africa.

Feeding ViraMatrix

Statistics show mortality on farms with PMWS appears to peak around 8-13 weeks of age. The table below presents an overview of farmer's findings on the effect of feeding ViraMatrix and the incidence of increased mortality, which may or may not have been due to PMWS.

On-farm observations of ViraMatrix in the diet
Diets with / without ViraMatrix Mortality levels
in the herd
(Wt 5-7kg)
(Wt 7-12kg)
(Wt 12-30kg)
Added Added Added No Increase
Added None None Increased
Added Added None Increased
None Added Added Increased
None None Added Increased

One observation that some farmers have made, which supports the data in the table above, is that when feeding ViraMatrix up to 7/8 weeks of age the mortality is very low, and it has thus been assumed that the "problem" has been overcome. The ViraMatrix is removed and then around 10 weeks of age the mortality suddenly increases. It would appear to be essential that the ViraMatrix is fed from weaning all the way through to 30kg liveweight to optimise the metabolic effect of the components within the product.

In situations where pigs have been brought on to a farm around 10-15kg, then feeding ViraMatrix from this age has been reported to have no effect on the incidence of mortality. In contrast, in studies where weaned piglets have been immediately moved to another farm and then immediately fed ViraMatrix, then this programme has been an aid in achieving the on-farm expected mortality (say 3-6%) between weaning to 30kg.

An interesting observation from a number of farms is that, with the reduction in mortality between weaning to 30kg liveweight there has also been a decrease in the incidence of porcine dermatitis and nephropathy syndrome (PDNS) around 50-70kg liveweight. The reason for this is not understood since the aetiology of the two diseases is quite different.

Growth Rates

In an high number of cases, farmers have reported and continue to report that piglets have a better "bloom" when fed ViraMatrix. In addition, where detailed studies have been conducted the ViraMatrix fed piglets are heavier (range 0.6-2.8kg) at 10-11 weeks of age compared with the average weight prior to using the product.

In a limited number of cases those pigs that have been fed ViraMatrix have been tracked through to slaughter (90-105 kg liveweight), and in these cases it would appear that the ViraMatrix fed pigs reached their target weights 5-9 days earlier. These combined observations certainly add to the general view, held both by farmers and veterinary surgeons, that a heavier and healthier pig at approximately 30 kg liveweight grows faster to slaughter.

Sows and Gilts

A very limited number of studies have been carried out in sows. This on farm observation was carried out to evaluate the effect of supplying additional anti-oxidants and bioflavanoids to pregnant sows (two weeks prior to farrowing) and its effect on piglet mortality. In the table below a simple field observation was carried out to evaluate the possible benefit of feeding ViraMatrix to the sows and/or piglets. The piglets were fed ViraMatrix immediately from weaning.

On-farm observations: Sows and Gilts
Sow Received ViraMatrix Piglets Received ViraMatrix Mortality in the herd
Yes Yes No increase
No Yes No increase
Yes No Increased

Despite the simplicity of the observations the results suggest that a factor(s) at weaning, which may be "stress induced", may trigger a mechanism in the piglet that results in it more readily succumbing to a disease challenge, such as porcine circo-virus 2 (PCV-2) or any other viral/bacterial invasion.

On farms with increased mortality, it is not uncommon to report a wider than normal variation in piglet weight within the same pen. If it is assumed at weaning that all piglets receive the same "stress factor", for example, then the observed variation will be a result of differences in the pig's ability to express its genetic potential, through a variety of metabolic pathways. The involvement of a "genetic factor(s)" in the susceptibility to or increased risk factors of succumbing to disease is a topic of increasing discussion within the human medical profession.

In the table below are some observations of the incidence of increased mortality in an herd. As with the piglet variation, there appears to be a variation in the incidence of increased mortality between parities.

On-farm observations: Mortality and Parity
Parity Sow 1 Sow 2 Sow 3
1 Increased mortality
2 Increased mortality Increased mortality
3 Increased mortality Increased mortality
4 Increased mortality

The above data are from a young herd. There are, however, various views and opinions that the age of the sow herd may be correlated with the incidence of increased mortality. The combined UK and overseas on farm observations reported here has come from gilt herds through to sows in their 7-11 parity and some even higher. It has to be stated, however, that more definitive data are required to ascertain if the age of the sow herd is one of the more critical factors.


In conclusion , there are incidences of higher than expected mortality in pig herds throughout the World. In some instances PCV-2 has been associated with such higher mortalities and on-farm observations suggest that this increased mortality may have a multi-factorial component(s).

As part of their efforts to reduce the incidence of this increased mortality, the introduction and correct use of ViraMatrix has been reported by farmers to show consistent benefits.

Farmer observations

Below lists a number of Farmer Observations following the use of ViraMatrix at the recommended levels.

From these observations it is becoming increasingly clearer that the benefit of feeding ViraMatrix is not only limited to a reduction in mortality between weaning and 25/30kg but also in improved feed intakes, healthier looking piglets and better performance to slaughter weight. The change in performance has also been coupled with changes in improved carcass confirmation. Therefore, it is essential to include in all financial evaluations for ViraMatrix not only the value of more pigs to sell but also the extra carcass value.

The observations of improved feed intakes, better bloom and an improved performance to slaughter is consistent with many farmers' views that a healthy pig at 30kg will grow faster to slaughter.

Farm 1 - England
The table below shows some average performance data from a UK farm. The farm has an excellent data recording system and thus it was easy for the farmer to pick up a change in performance between weaning and 25/30kg liveweight.

It is easy to identify the piglets that have definitely got PMWS, but more difficult for those pigs that are borderline. The results from the farm recording clearly show the negative effects of PMWS on herd performance. The farmer started to use ViraMatrix and within an 8 week period was seeing substantial reductions in mortality. The farmer reported that the piglet's feed consumption increased when being fed ViraMatrix. In addition, the piglets had a better "bloom" and generally looked healthier. The farm continues to use ViraMatrix and the performance figures post ViraMatrix have returned to the pre-PMWS level.

On-farm observations: ViraMatrix usage
Weaning to 28kg Previous 6 months prior to PMWS Diagnosed Pre ViraMatrix with PMWS Diagnosed Post ViraMatrix with PMWS Diagnosed
DWLG (g/d) 483 431 488
DFI (kg/d) 0.81 0.78 0.86
FCR 1.68 1.81 1.76
Mortality (%) 4.7 12.9 6.2

Pigs have been followed through to slaughter (85-92kg target slaughter live weight) and on average there has been a reduction in the days to slaughter by 4-7 days. The value of a reduction of one day to slaughter is always open to debate. But if just the feed cost is taken in to account, then assuming a finisher feed cost of say £120 per tonne then a 7 day reduction could worth approximately £2.30 (3.56 euro) per pig.

Farm 2 - England
Recent observations from another farm in the UK has also confirmed the benefits of using ViraMatrix. The presence of PMWS was not clear but there was an increasing problem with mortality. One of the factors associated with the increased mortality was diagnosed as Mulberry heart disease. An increased level of Vitamin E/selenium had been fed with no benefits. In addition, higher levels of therapeutic drugs had been included in the pig diets with limited success.

The farmer started to feed ViraMatrix and observed the usual reductions in mortality but also saw a significant reduction in Mulberry heart disease. More detailed investigations in to this observation are being carried out and some interesting changes in blood parameters have been observed.

As well as a reduction in mortality the farmer has reported that the feed consumption of the piglets had increased between weaning and 25kg. Plus the piglets looked healthier and had a better "bloom" according to the farm manager.

At 8 weeks of age the piglets were on average 1.6kg heavier than previous batches. At 11 weeks of age the piglets fed ViraMatrix were on average 2.4kg heavier than prior to using the product. The piglets are being followed through to slaughter and the interim weighing at 60kg is indicating the pigs are 3-6 days ahead of the previous schedule. This is consistent with both farmer and published data that a heavier pig at 30kg will reach slaughter weight faster.

Farm 3 - Germany
This is a progressive farm with an all-in-all-out programme from weaning to finish: slaughter at 105kg liveweight. The farm is a minimal disease unit that is PRRS positive plus there is a vaccination programme for pneumonia.

The normal post weaning mortality through to 30 kg in the latter part of 2000 was running at 2-4%. In the early part of 2001 the farm appeared to have a "wave" of PRRS go through the unit, from which point the mortality rose to 8-10% between weaning and 30 kg liveweight. Then progressively through 2001 the mortality kept rising to 12-14% and there was an increasing mortality in pigs around 50-70kg.

There was no obvious PMWS but the latter deaths at 50-70kg were diagnosed as porcine dermatitis and nephropathy syndrome (PDNS). ViraMatrix was tested on the farm from October 2001 and the table below shows some of the results where pigs were separated for trial purposes. It should be noted that the feeding of ViraMatrix stopped at 35kg live weight.

On-farm observations: ViraMatrix usage
Batch No Pigs % Mortality
(Up to 30kg)
Days to Slaughter from Birth
Non ViraMatrix pigs 250 15.7% 193
ViraMatrix treated 260 5.6% 187
ViraMatrix treated 280 3.8% 182

The farmer keeps detailed records and one interesting point was the differences in days from weaning to slaughter at approx. 105kg liveweight. The pigs were fed the same diets specifications, with and without ViraMatrix. As well as the decrease in mortality between weaning and 30kg liveweight, the farmer noted that the mortality in pigs between 50-70kg was also significantly reduced to almost zero.

In addition to the improved days to slaughter there was a beneficial change in the feed conversion ratio between 35kg to 105kg. The faster growth rate was coupled with a reduction in feed conversion ratio by 0.15 to 0.18 units.

There were not only benefits in performance but also in carcass confirmation. The percentage lean in the pigs fed ViraMatrix was on average 0.8-1.1% higher. This change in lean percentage is consistent with the faster growth to slaughter weight. The value of this extra lean percentage on overall farm profitability should not be underestimated.

Farm 4 - France
The leading feed compounder in France has recently been evaluating ViraMatrix. The observations they have seen are very similar to that reported above in the German studies.

In their most recent trials the level of mortality on farms with PMWS has decreased from 10-15% down to 1-4%. The pigs have a better bloom and in all cases the farmers have reported an increase in feed intake after only being on ViraMatrix for three weeks.

The pigs have been followed through to slaughter and there have also been improvements in days to slaughter, feed conversion ratio and lean percentage. In terms of feed conversion ratio an improvement of 0.21 to 0.34 units has been observed. In relation to lean percentage this has improved by 1.0-1.3%.

In is essential to calculate the value of using ViraMatrix. When comparing the value of the improved pig performance and mortality with the cost of ViraMatrix, the return ratio has been calculated at approximately 7:1. This is a considerable return to the farmers who have been suffering from the ravages of PMWS.

Farm 5 - Czech Republic
This farm had a significant pneumonia problem as well as being PRRS positive. In mid 2001, mortality was running at 5-8%. For the remainder of the year there was a progressive increase in mortality rising to 28% by May 2002. The farm tried to improve the health status of the weaners by carrying out a variety of management changes and used a wide range of cleaning agents but this brought little success.

ViraMatrix was added to the feed at the start of June 2002 and the table below shows the monthly results from April 2002. As the months progressed fewer and fewer pigs in the system showed symptoms of PMWS.

On-farm observations: ViraMatrix usage
Month % Mortality
May 2002 28.1
June (Intro ViraMatrix) 24.2
July 19.7
July 14.6
Aug 8.4
Sept 6.2
Oct 3.8

For each 1% reduction in mortality the farmer had calculated the cost was approximately 0.3 euro per pig on a total farm basis. The reduction in mortality has saved him £4.70 (7.29 euros) per pig which also takes account of the inclusion cost of ViraMatrix.

Farm 6 - Slovenia
Here the farm had seen a consistent increase in mortality over a 6 month period rising to around 12%. This level was not acceptable since the majority of the pigs from the farm were being exported. In September 2002 the feeding of ViraMatrix commenced and by December 2002 the mortality had decreased to fewer than 5%.

The main reduction in mortality occurred between weaning (7kg) to approx. 16kg. In the period 16-25kg the mortality was zero. In terms of number of pigs for sale the use of ViraMatrix has improved overall farm profitability by £3.13 (4.85 euros) on a per pig basis.

Further results are awaited on the performance of the pigs to slaughter and carcass confirmation.

Further Information

If you would like to receive further information about ViraMatrix, simply email us at and we will arrange for details to be forwarded. ViraMatrix is available (and in use) throughout most of the main pig rearing countries world-wide.

Source: Dr Brian Vernon, Park Tonks Limited. - January 2003