Managing gilts for a bright future

Increased productivity
Piglet production has increased significantly over the past years. In 2023, the average productive sow in South Africa weaned 29.3 piglets per year. Two piglets more than 10 years ago. The increased production puts more pressure on the sow. Preparing the sow for a highly productive life, therefore, already starts at birth.

It starts at birth
Choosing the right female piglet at birth already lays the basis for a well-developed breeding sow. Do not use piglets with a weight lower than 1.2 kg as a breeding sow, as body development will be lower during her life. In contrast, piglets with birthweight >1.6 kg will grow too fast. Figure 1 shows the typical weight development of gilts up to the 2nd weaning, with two distinguished phases. The developmental phase, from birth up to first insemination and the functional phase, from first insemination up to culling. During the developmental phase, we expect continuous growth, which should continue up to the first farrowing. During the functional phase, up to the 5th parity, a gilt will still grow but growth is disturbed by weight loss during lactation.

Figure 1 Gilt development from birth to 2nd weaning (source SNC Elsenpas, De Heus)
 
Growth rate, body weight and fat
Body weight at first insemination, combined with age, is often used as a key figure to determine whether to inseminate a gilt. It is also a good predictor of future reproductive performance. Body weight development is determined by average daily gain. For gilt's lifetime growth, growth from birth until first insemination is often used to assess gilt development. As a rule of thumb, the aim is to achieve a lifetime growth of between 600 and 650 grams/day. Lower lifetime growth, <550 gr/day, can lead to underdeveloped gilts which will negatively influence reproductive performance. Too high lifetime growth, >700 gr/day, can negatively influence reproductive performance and reduce sow longevity. Following the average lifetime growth, in turn, leads to a body weight at first insemination between 140 and 170 kg at an age of around 230-250 days. Please note that the optimal weight and age at first insemination depends on the breed. Always consult the manual of the breeding company for the latest updates.

Body fat is an easily accessible energy source for lactating sows. Besides weight, body fat is also important for highly productive sows. At first insemination, a back fat level of 12-15 mm is advised.

If you purchase gilts around first insemination or when they are already pregnant, you can use this information to check body development and support growth after gilts arrive on your farm.

Feeding strategy up to first insemination
Having the right feeding strategy, feed combined with the right feeding schedule optimizes gilt development. Up to 25 kg gilts can be fed like any other piglet. For both, the focus is on good body development and health. From 25-50 kg it is advisable to use a specific gilt feed. Whilst the requirements for body development of gilt are like those of a grower pig, the gilt requirements for vitamins and minerals are different. They require specific vitamins and minerals to support the development of the reproductive tract as well as bones. From 50 to 120 kg a specific gilt feed is a necessity. Gilt feed should support muscle as well as fat development and a lower growth rate compared to fattening pigs. Vitamin and mineral requirements are the same as those of the 25-50 kg phase. When you buy gilts around the age of first insemination, it also pays to use a specific gilt feed. During this phase, you still want to support gilt development. The gestation feed is often too low, whilst a lactation feed is too high in nutrients. The general advice is to feed gilts ad libitum up to 60 kg, after which a restricted feeding schedule should be followed.

First insemination
Two weeks before first insemination, gilts should be housed in (insemination) crates to get used to being confined. This helps to improve the oestrus expression. During this time, you can feed either the gilt feed or a gestation feed. Start oestrus stimulation 5 days before the expected date of insemination. Oestrus stimulation, boar exposure, light, and flushing, are done in the same way as it is done with sows. For gilts, it is important to make sure you do not inseminate them before the 2nd estrus, as this negatively affects performance.

•    Check for oestrus twice a day.
•    Use a teaser boar and keep him in front of 5 sows for at least 10 minutes.
•    Use a 16-hour light and 8-hour dark lighting regime.
•    Feed 2.5-3.0 kg gestation feed topped with 0.5 kg of Maxi-Flush or sugar (Figure 2).

Figure 2 General feeding advice for the 6 days before insemination. Blue bar is gestation feed, green bar is Maxi-Flush or sugar

First gestation
After insemination, a gilt should be fed a gestation diet using a step-up schedule (blue line in Figure 2). This supports gilt development as well as the growth of the litter. If possible, use a specific gilt gestation diet, since gilts need more nutrients for growth than do sows.

Figure 3 An example of a feeding schedule for a gestating gilt. Exact values depend on the gestation feed and gilt condition.

Conclusion
Gilts are the future of your farm. Correctly managing their development from birth up to first farrowing prepares them for a successful career as a sow. Frequently measure body weight during the rearing phase to check if the development is on track and adjust the feeding strategy if necessary.

Always use the advice of the breeding company as a starting point and, if necessary, adjust together with your technical advisor - https://www.deheus.co.za/meet-our-team.