Neonatal Mortality- New Challenges and Solutions for Hyperprolific Sows

Introduction

Neonatal and pre-weaning mortality represents a very large wastage and loss of efficiency for most production farming businesses. Irrespective of the production system(intensive or extensive) the level of pre-weaning mortality still stands around 11-12% of all piglets that are born alive. The range in this probably is between 8% and 25% in general if we consider national statistics. Even the top 10% of performing herds in the UK database only achieve between 8 and 10%.

The reasons for these losses are well known. Overlying by the sow where piglets are crushed when the sow lies down quickly in a farrowing crate account for about 50% of all losses and these losses usually occur within the first 2 to 4 days after farrowing. Farrowing crates came into existence back in the 1960's to contain these losses as far as possible and many design features have been nowadays built into these systems to improve their performance. There is also no doubt that without a regular farrowing crate then mortality levels quickly rise to around 30% of all pigs born alive. They are however not a perfect system and there is still much on-going debate in Western Europe about the fact that the restraint of the sow in the neonatal days and up to weaning in crates is an animal welfare issue. As a consequence within EU countries there has been much research and discussion with supermarket chains on this perceived welfare problem and of course any future legislation changes will impact on any country importing pig products into the EU.

It is the purpose of this paper therefore to review some of these issues and problems and to explore possible solutions.

A final complication in these arguments is the recent appearance of new hyperprolific dam lines from some of the breeding organisations. Over many years, for example, the Danish breeding organisations have focussed almost exclusively on litter size as a single genetic selection objective. Most of the alternative breeding organisations during the same time focussed on multi-trait selection and traits such as growth rate, feed intake, FCR and carcase lean content. As a consequence after many years of using such techniques as family selection and progeny testing we now have dam lines that are capable of producing very high litter sizes of over 14 born alive in parity 1 rising to over 15 born alive for the multiparous sows. In the UK also there are hyperprolific dam lines that have been generated in a similar way but which have also incorporated Chinese Meishan genes into the populations that naturally are hyperprolific. The upshot of all this is that using these dam lines in commercial production will yield a level of annual sow productivity of 30 piglets per sow per year and over. This was thought unattainable only a few years ago but is now reality. Some of the top 10% of herds are now achieving 35 piglets per sow per year.

These changes bring problems of their own despite the huge commercial potential from utilising these genetic lines. One of the principle difficulties is that birth weight is significantly reduced and rather than seeing most piglets being 1.4 kg at birth and over, the average may fall to around 1 kg or less. Inevitably this is then linked to more problems in the neonatal phase and increased deaths of new born piglets. This has been picked up in Denmark recently by the animal welfare lobby and there have been some press articles along the lines that "25,000 piglets born every week that are born to die immediately" . There is obviously a need here to introduce new technologies to accommodate these difficult changes. The new genes are already showing enormous promise and potential for significantly increasing breeding herd performance and financial output, but we must find ways to be able to rear them all successfully to weaning.

Table 1

Danish National Herd Performance

 

In Table 1 are given data from the national herd statistics from the Danish industry. It can be seen that according to these data the top 10% and 25% of producers whilst producing significant numbers of piglets per sow and excellence in reproductive output, they are also managing their neonatal mortality so that this is still acceptable and a high level of performance. It is therefore not an inevitability that with high prolificacy we also experience high mortality but it probably requires a re-think of all of the factors that determine neonatal and pre-weaning mortality.

 
In Table 2 are presented some recent data from the UK industry. Productivity has been rising rapidly also in the UK since the end of PMWS disease but we have not yet reached the level of the Danish industry. The data in table 2 also demonstrate that with high production levels we can also experience relatively low levels of mortality.

In the UK recently we have launched a national ‘2 Tonne Sow' programme to encourage farms to focus not on simply prolificacy and breeding performance but the wider index of the number of kg of pork (saleable meat) produced per sow per year. At the time of writing (2010) the UK is averaging out at 1600 kg of pork produced per sow per year whereas the Netherlands, France and Denmark are over the 2 tonne target. This is partly because killing weights are higher in theselatter countries compared to the UK, but they also have achieved better overall breeding herd performance and are more prolific in general.

Causes of Neonatal Mortality

It has been cited above that overlying or crushing by the sow is a major cause of mortality in neonatal piglets. The other principal causes are disease, often contracted via the sow herself at the time when immunological education is also conferred via colostrums and sow's milk. Many piglets also die in the neonatal phase from either under nutrition / starvation when they cannot compete with litter mates for udder position and also hypothermia which is related to the under nutrition. The relative importance of each of these factors has been reviewed and analysed many times in the last few years and it is not intended to re-visit this analysis here.

Commercial Solutions

There have been many attempts over the years to refresh and refine the conventional farrowing crate to improve the level of mortality. Even 10% pre-weaning mortality is a huge waste of potential pig sales and is an enormous economic and welfare problem.

The mechanical crate solutions include the use of devices to remove the high risk neonatal piglets from the high risk zone around the sows feet and body. The mothering ability trait is also well understood from a genetic point of view and certainly some breeds like the British Saddleback are well known to be careful when lying, standing up and generally changing posture. Others perhaps like the more prolific European White breeds are a little more clumsy in this respect and with bigger litters this makes matters worse. Over the years the commercial companies involved in farrowing crate design have optimised and re-designed the structures to ensure improved performance. We have also see design features such as the use of infra-red beams to identify when sows are standing or lying and linked to cold air blowers to encourage piglets away from the ‘killing
zone' .

This latter feature has been taken a stage further in a new design recently from a Dutch company. This has a pneumatic system built in to each crate which can adjust the height of either the sow's farrowing area or the piglets creep / lying area alongside. When the sow stands, the release of a pressure pad ensures that the creep areas fall quickly to a height that is about 12-14 cm below the sows lying areas. Piglets within the creep areas cannot then stray into the sows ‘high risk' zone and any already under the sow quickly fall down onto the creep area. Alternatively when the sow lies down again the pressure pad is activated and the two floor areas equalise again and piglets can then suckle and access the sow in safety.

These installations are not new but they have continued developing and there are some of these already installed on farms in the UK. The anecdotal evidence on this is that pre-weaning mortality can be reduced to between 4-6%. If this is repeatable then even despite the high costs of the crate, when used with hyperprolific sows, these crates pay for themselves very quickly.

At the other end of the spectrum in farrowing technologies is the ‘high welfare' freedom farrowing crates in the UK. Many of these have been investigated over the years and all have fallen down on their ability to protect piglets from crushing.

There has been a so-called Pig Safe programme running in the UK funded by DEFRA (Ministry of Agriculture) to attempt yet again to construct a crate that will meet both the welfare requirements of the sow but also protect piglets. It is early days as yet but the early results have shown mortality levels of around 18% and hence this may still be unacceptable in commercial terms. The second technique that can be brought to application with hyperprolific sows herd is the use of supplementary rearing devices. When some sows farrowing in groups produce 15-16 piglets in one litter it is very hard to envisage that individual sows can rear them all. They just do not have the milk production capacity of physically enough teats to nurture all piglets. At the least they start off with low birth weights and then have low weaning weights - and it is well known that this translates into reduced growing pig performance to slaughter. Any advantage in prolificacy is negated by the loss of grower / finisher performance.

Management techniques are hence often used in Denmark and other countries in Europe such as complex cross fostering programmes sometimes involving ‘nurse sow' solely used to foster off surplus piglets and which lactate for very prolonged periods.

There are also many systems in practice for artificially rearing surplus piglets and there are commercially available liquid milk products used to good effect in this way. The results with some of these can be encouraging and may be a necessity with very hyperprolific herds. The so-called Rescue Decks developed in North America have now been installed on many high producing farms. These are purpose built yet relatively simple devices for rearing both orphan and surplus piglets from around 4 days onwards after hopefully all piglets have had colostrum. The environments are thermally controlled and the supply of a liquid milk supplement is via a well designed bowl system for easy access. Early results in the UK look promising and the claims are that even despite the cost of liquid milks and the investment in the equipment, these give a good return on the investment.

Conclusions

If we are moving towards production farms seeing a much greater level of productivity than we have achieved in the past then this needs carefully thinking through from a management viewpoint but also a practical point. There will be a need for looking at and installing new technological features into the business such as improved crate features and supplementary piglet rearing devices. It may be that ultimately we may arrive at an optimal production position with no more than 30 piglets per sow per year being the target. Any more than this and it becomes a significant welfare problem and maybe consumers and supermarkets will not tolerate this change.

In countries like China and Vietnam of course where labour is plentiful and cheap still, they can solve the problems with 24 hour surveillance in the farrowing units and this prevents neonatal losses. This is of course untenable in most other areas of the world where pigs are produced and farmed. The technology inputs are therefore essential.