Prepare gilts today for successful sows tomorrow

Date published: 12 August 2024

To maximise herd output and profitability replacement gilts need to produce large litters and continue to perform for at least six litters.

Influence of gilts

The performance of today’s gilts is dramatically different to that of replacements used even only 10 years ago! College of Agriculture, Food and Rural Enterprise (CAFRE) pig advisers regularly analyse the physical performance of breeding herds using computer management software. It is obvious from Graph 1 that gilt output, in terms of numbers born alive, has increased dramatically and is continuing to do so.

However, data for the 2023 year, which recorded the performance of almost 32,500 sows, showed that there is a wide range in gilt litter size between herds. Although the average litter size was 15.1 piglets born alive, the difference between the top and bottom 25% of herds was over two pigs per litter, with a wide difference in output between the highest and lowest performing herds of 4.5 pigs.

As approximately 20% of farrowing’s are from gilts, any improvement in gilt litter size will greatly influence herd output. Equally important is that good gilt litters are associated with good litter performance in later life. Indeed, analysis of the computer management data confirms that there is a very strong relationship between gilt litter size and average herd litter size.

Mark Hawe, local CAFRE pig adviser says that: “Replacement gilts must be prepared to withstand the rigors of breeding life. The significant effect that culling gilts or young sows has on herd output and profit is often not appreciated as it is only when sows reach their third parity that all replacement costs are covered.”

CAFRE physical benchmarking figures show that the average replacement rate in the Northern Ireland herd is approximately 45%. In practice this means that almost half of the sows in the herd are ‘turned over’ each year. Indeed, some herds have a replacement rate closer to 60%. If these culls are gilts or young sows, it is easy to appreciate the damaging affect early culling can have on profitability. So how do some pig producers achieve large gilt litters and longevity in sows. Well, they will tell you it’s all down to preparing the foundation!

Prepare from birth

On some pig units, gilts are the ‘forgotten minority’ with the only preparation being a tag in their ear shortly after birth to show that they were produced from dam-line semen. These potential gilts are then reared just like any growing pig up to slaughter weight and only then are they assessed for their suitability as a future mother. By that stage the damage has been done!

Mark advises that: “Good preparation starts at birth by maximising colostrum and milk intake to achieve strong healthy pigs at weaning.” Extra care should be taken with gilt piglets to ensure teats are not damaged, especially if floors are worn. Front teats can be protected with gaffer tape to ensure all teats are functional at selection. Replacement gilts are often kept with other pigs during the first and second stage growth periods but ideally, they should be assessed and penned separately from approximately 30 kg onwards.

Mark continues that: “Arguably feeding is the single most important factor that determines the quality of gilts at service. Replacement gilts should not be fed ad-lib with growing and finishing pigs – this is not an option!” Growing and finishing pig diets are formulated to maximise growth and feed efficiency whilst producing an acceptable lean carcass at slaughter. Gilts on the other hand should be reared to achieve a target weight at service, which results in a lower growth rate, giving the reproductive organs, legs and feet time to develop to encourage a long productive life. Also, a higher level of fat is essential to withstand the rigors of first and subsequent lactations.

The optimum weight for age at service is usually around 150 kg at 240 days but the breeding company supplying the genetics is best placed to advise on this. As modern gilts have great growth potential, achieving this target requires restricting feed throughout the growing period. Having smaller groups of gilts that are penned according to size will help control intake and ensure uniformity at service. But growth rates are not simply achieved by restricting the amount of dry sow ration, or worse finisher ration, fed. Specifically formulated gilt rations are essential to ensure the correct levels of nutrients, minerals and trace elements are available and in the correct proportions to limit growth, strengthen legs and feet whilst optimising body condition for service. This requires expert help from a nutritionist.

Stimulate puberty

Maiden gilts should be kept in stable groups and in the same pen from at least 90 kg to first stimulation. The stockperson should walk through these pens each day, so gilts become familiar with people. This also gives the stockperson the opportunity to continually inspect gilts for good leg placement, locomotion and of course teats and udder. It is essential that gilts are kept in a calm environment at this stage to avoid early onset of heat, so movement of other stock in and out of the house should be kept to a minimum and a boar should never be in this area. Although a specific vaccination policy is essential for each herd, every effort is made to reduce stress when vaccinating.

As service is usually at second heat, gilts need to cycle naturally at least once before insemination. So, it is ‘all change’ for the gilts to encourage the onset of heat. This includes:

• Moving them from the ‘calm’ gilt house to the ‘active’ service house.

• Feeding a high energy diet ad-lib.

• Keeping them in a pen beside ‘unfamiliar’ active sow.

• Check for heat twice each day.

• Providing ‘good’ boar exposure to an old boar and ideally full boar contact.

• Moving the boar well away from the gilts when not heat detecting.

• Using boar pheromone sprays during boar contact to help heat detection.

The success of gilt preparation can be measured by the spread in time it takes for all gilts in the pen to show signs of heat – good synchronization indicates good preparation. Then it’s back to the tranquility of the gilt house for further preparation for service at the next or subsequent cycle.

Mark concludes that: “Extra input into gilts takes extra effort and expense. But as good gilts are the foundation of a productive herd, it is a sound investment.”