Are breeding policies optimising genetic progress?

To maximise output, producers must try and harness more of the genetic potential available in their herds. From a breeding perspective, an evaluation of replacement policies might be timely as decisions made in the past, say to cut costs and minimise health risks, could be holding back productivity. Jane Jordan considers the F1 debate

Maintaining genetic improvement should be a pivotal objective of any pig production enterprise. In an ideal world commercial herds should be able to capitalise on the incremental advances made year on year by genetics companies to improve productivity at every stage.

By accessing more of the genetic potential available in modern genotypes, businesses will improve productivity and a balanced appraisal of the breeding strategy could help unleash more of this untapped reserve.

Purchasing F1 parent gilts from a breeding company enables commercial herds to keep pace with genetic advances. An in-house replacement policy cannot replicate the speed of genetic progress achieved from buying-in replacements, but the benefits can be significant and financially valuable if the breeding programme is carefully managed.

“Many factors encourage producers to breed their own female replacements, the main ones being herd health protection and cost reduction. These are valid reasons, but other factors do warrant consideration and particularly in a market environment that is demanding greater efficiency and increased productivity,” says Simon Guise, UK Sales Manager with Rattlerow Farms (pictured above).

Some in-house programmes do achieve exceptional results, and Rattlerow has many customers that breed their own replacements and consistently achieve top 10% performance. But these businesses are well managed; are experienced and have a sharp eye on record keeping and data analysis. Rattlerow also works with these businesses to analyse the genetic values of their breeding females, which helps them to maximise genetic progress.

However, others using in-house herd multiplication and produce/select their own F1 (sometimes F2) gilts could be missing out on the worthy advances made to key traits such as prolificacy, growth rate and FCR, seen in recent years. The health status of these herds might be exceptional, but genetically they are becoming outclassed and in many cases performance does appear to be reaching a plateau.

“The genetic lag associated with in-house breeding programmes is well founded and although closing a herd might seem appropriate, if the replacement programme is not managed to maintain steady genetic progress, then in the long term this will curb a herd’s performance potential and production quality,” says Mr Guise.

Technical support services, such as Rattlerow’s Genmatch, do allow those breeding their own gilts to establish the best criteria for their individual programmes. Producers can use breeding company resources to determine the genetic value of the females in their own great-grand parents female (GGP) and grand parent (GP) populations, thus improving the accuracy of selection routines. However, the genetic benefits of such a policy still cannot match those offered by purchasing replacement gilts directly from a breeder.

Realistic risks, balanced benefits
During the past decade the pig sector has worked hard to stabilise herd health status and most producers now have a greater understanding of disease control and work closely with their vet to maintain effective acclimatisation routines. This, combined with advances in vaccination programmes and proactive biosecurity, means that the health risks associated with buying-in replacement gilts are considerably lower than they were 10 years ago.

By purchasing F1 gilts, commercial farms can manage a simple breeding programme that gains an immediate benefit from 100% heterosis. Here’s how:

All females will be the same hybrid genotype, produced from crossing two different GP lines. When a different terminal sire line, such as a MaxiMus, is used for every mating (boars and semen), then this three-way cross ensures 100% heterosis in the progeny. This achieves maximum hybrid vigour and is expressed in production benefits.

All slaughter progeny will also be a standard genotype, with known genetic capabilities that a business can work towards achieving.

“At commercial level this is the swiftest means of gaining genetic improvement as it continuously takes advantage of the progress being made in the nucleus. The finishing herd should exhibit less variability with greater uniformity in conformation, growth, leanness and carcase quality,” says Mr Guise.

By comparison, an in-house replacement programme cannot achieve equivalent ‘heterosis’ as the full benefits of this phenomenon are only achieved in the slaughter generation, and not at the GP or parent stage.

Herds breeding their own gilts also have fewer sows available for commercial pig production as they must maintain a core number of purebred GGPs to generate the purebred replacements required by both its GGP and GP population. Consequently, a proportion of the rearing herd will always include purebred and parent damline progeny (boars and unselected gilts), which does have implications.

“Around 8% of the output of herds with in-house replacement programmes is generated from damlines and does not have the same genetic potential for growth and performance as the commercial slaughter progeny. This will influence overall herd efficiency, often by lowering performance and reducing uniformity,” Mr Guise explains.

Rearing herd growth rates and backfat levels also tend to be more variable in these herds and unless an alternative market can be found for the damline-derived finishers, this can also hold back profit potential.

Strict disciplines
Managing an in-house replacement programme requires discipline. Unit facilities and staff must be able to provide the very specific needs that breeding gilts have throughout their growth and maturation. Ideally, F1s should not be reared within mainstream commercial production. Using the same production process for all growing pigs – replacements included – will either affect productivity/performance of the slaughter generation or compromise gilt quality.

“For gilts, the focus must be on developing condition and optimising body reserves, not fast, efficient growth and herds breeding their own replacements do tend to use separate accommodation and feeding regimes,” says Mr Guise.

Numerous studies show that maiden gilts must have adequate fat reserves at mating and throughout their initial breeding cycle to reduce their first weaning to oestrus interval and sustain subsequent long-term performance (to parity six). Rattlerow has found that feeding gilts a higher energy to lysine ratio diet in the latter stage of rearing encourages this vital fat deposition and controls lean growth.

Another negative trait associated with in-house programmes is the inclination to take gilts out of the finishing house when service numbers fall short. But using substandard females perpetuates genetic lag, with long term implications for herd productivity and performance.

“Unless these gilts are culled at weaning and their progeny is tracked to ensure they are also removed and never selected as potential breeding females, this is perhaps the most damaging way to compromise a herd’s genetic progress,” says Mr Guise.

Whether purchasing replacement gilts or producing your own, it is clear that a successful breeding policy relies on good communication and a confident and open working partnership between all parties involved – producers, vets and the genetics supplier. As Simon Guise points out, such a relationship builds trust; helps to satisfy business objectives and is worthwhile for both breeding companies and their customers.

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