Uninterrupted gilt development and a solid genetic make-up for development of the body and reproductive tract are prerequisites for the production of gilts having an optimum start in production.

Management of the gilt up to the time she weans her first litter has a major influence on lifetime productivity and, consequently, Weaning Capacity. Size of first litter has a strong correlation with subsequent litter sizes, so achieving a large first can be a good indicator of more piglets born and weaned in a sow’s lifetime. Correct management during the breeding female’s early life will also positively influence her longevity, increasing litters per sow’s lifetime, which is a key factor in maximizing Weaning Capacity.

Today’s gilts are extremely lean and therefore vulnerable to any deficiencies in nutrition, environment and management. It is critical that all these aspects are optimized in order to ensure that the maximum number of young females survive to second parity and beyond. Attention to the many factors that contribute to a long and productive life will ensure success and the following information is intended to provide a checklist of the most important points.

Acclimatization

If incoming gilts experience a significant health challenge when they enter the herd, their lifetime productivity will be reduced. Acclimatization protocols should ensure a gradual exposure to the disease organisms already prevalent in the recipient herd so that gilts do not become clinically sick. Timely vaccinations should also be carried out in accordance with veterinary advice. There is a certain advantage of systems like BioHypor, where gilts are reared on the same farm where they go into production as sows. These gilts are able to build up natural immunity for their future farm environment and have less chance of developing problems due to mismatches in the vaccination programme.

Environment

Pen space

Ideally gilts should be housed in groups until just prior to breeding, with sufficient space to exercise and develop strong legs. A minimum area of 1.5 m² (16 ft²) per gilt is recommended and, ideally 2.0 m² (21.5 ft²). Adequate space is essential to allow gilts to stimulate each other as they come into oestrus and for the boar to move freely around the pen during stimulation and oestrus checking.

Group size

A group size of 6-8 is ideal because this improves boar-to-gilt contact during heat detection. In large groups the likelihood of the boar achieving nose-to-nose contact with every gilt and identifying all gilts in oestrus is reduced. Therefore a group size of 10-12 should be considered a maximum.

Flooring

Provision of a dry, non-slip floor will provide good grip and minimize injury, which is especially important during the boar stimulation and heat checking procedures. Where possible, straw or wood shavings should be used to improve grip in gilt pens.

Lighting

Light plays a major role in stimulating the onset of oestrus but, unfortunately, is inadequate in many barns. A minimum light intensity of 100 lux is recommended and ideally 150 lux should be used, with a lighting period of 14-16 hours per day.

Feeding prior to Breeding

After entry to the herd, gilts may be fed ad libitum or a restricted amount, typically 2.3-2.5 kg (5.1-5.5 lb) per day. If feed intake is restricted, feed intake should be increased to 3.0-3.5 kg (6.6-7.7 lb)for a period of 14-21 days prior to the expected breeding date to achieve a “flushing” effect, which helps to maximize ovulation rate.

Ideally, a gilt developer diet should be used between entry and breeding because such diets contain higher levels of minerals such as calcium and phosphorus, which results in a stronger bone structure.

For more detailed recommendations, consult the Hypor Nutrition Manual.

Boar Stimulation and Heat Detection

Effective boar stimulation is essential to encourage the rapid onset of oestrus following entry into to the herd or transfer to the gilt breeding area. Ideally, boar exposure and heat checking should be carried out twice per day. Sufficient time should be spent to provide intense stimulation to every gilt through nose-to-nose contact with the boar.

The operator should manoeuvre the boar around the pen to ensure this occurs, while observing for signs of oestrus and checking for standing heat using the back pressure test. As a guide, the time spent in the pen should be 10-15 minutes for groups of 6-8 gilts and 15-20 minutes for 10-12 gilts. The number of any gilt showing signs of oestrus or in standing heat should be noted on the gilt record card along with the date. The effectiveness of boar stimulation will be increased where gilts are housed well away from boars except during the stimulation procedure.

Weight at Breeding

With today’s lean genotypes it is essential to ensure gilts are bred at a sufficiently high weight so that they have adequate reserves of protein and energy (backfat) to carry them through their first reproductive cycle. This will help to maximize first litter size and will also help to improve longevity and lifetime productivity.

Work at the University of Alberta has shown that the optimum weight range for gilts at first breeding is 135-150 kg (298-331 lb), so that they reach farrowing at a weight of 180-190 kg (397-419 lb). Age is very unlikely to be a limiting factor and therefore need not be considered. Gilts should also be bred at a minimum of second oestrus. Early boar stimulation will help to establish strong heats and lead to improved ovulation rate and litter size.

Handling

Positive contact with people is an essential part of the procedures for integration of gilts into the herd. Work by Dr Paul Hemsworth at the University of Melbourne in Australia, has shown that gentle handling of gilts and sows leads to improved reproductive performance compared to minimal handling or negative behaviour by the stockperson. Therefore, when new gilts are introduced, daily contact should be provided by stroking, rubbing, scratching and talking quietly.

The Importance of Genetic Traits

Heat related traits, namely age at puberty and weaning to mating interval, have been core traits in Hypor’s breeding goal since the introduction of BLUP in the breeding program. These traits have decent heritability and the result is gilts that start showing their first heat at a very optimal age. This enables our gilts to be bred at their third oestrus.

Research has shown that delaying breeding to the third oestrus can result in about 0.25 additional piglets per litter for every oestrus skipped, and a sow that is better developed for a long and productive life. In Hypor breeding stock, the percentage of repeats on average is very low – under 10 per cent. This reduces involuntary culling rates in the herd, which makes it easier to get the right parity distribution in your herd and plan the replacement gilt flow.

January 2009