Getting The Best Results From Gilt Mating Using AI

By John Goss, PIC UK - This is the third of three articles by John Goss dedicated to the improvement of AI technique and results.
calendar icon 24 October 2005
clock icon 5 minute read
Pig Improvement Company UK

BQP has been operating a gilt mating unit very successfully for several years to restock its outdoor herds on a planned, regular, rotational basis. Results for the last 1400 PIC Camborough 12 gilts mated at the unit are a very creditable 11.4 pigs born alive with a conception rate of 90%. What lessons can we learn from the excellent results on an all gilt mating unit?

In the eyes of the manager, Steve Milnes, good results start with good preparation. When the gilts arrive at the unit around 40kg and 80 days of age, a good grower ration is fed ad lib to 19 weeks of age when they will have achieved an average of 70kg. At this point, the feed is restricted to 2.75kg of a specialist gilt rearer ration to provide extra minerals, vitamins and lysine and to restrict excessive growth.

There are strict targets to be aimed for to get gilts ready for service - a minimum target weight of 130kg (the average has been 135kg) with a minimum target age of 230 days (the average has been 235) and P2 fat levels of 18-22mm. Steve Milnes feels that if gilts are to survive a long productive life outdoors and produce a good, first litter, they must be right at first service.

Gilts are bought into the unit at planned intervals to allow sufficient gilts to reach service weight for each batch of the seven batches - three week serving cycle. Sufficient gilts are on hand for each batch for gilts to be naturally chosen to fit in without using oestrus regulators.

Initially, 250 gilts are taken in at the appropriate time to ensure gilts are ready for the required batch. On the Friday, three weeks before anticipated date of service, 8-10 vasectomised boars are introduced into the group to stimulate oestrus. Experience has shown that around 60% of gilts show oestrus between the following Sunday and Wednesday.

As gilts show oestrus, they are removed from the group and batched up into groups of 25 and run with two V Boars which will be removed after a week. "Flushing" of the gilts takes place using the gilt rearing ration fed at 4kg/head.

On the Friday, four days before the expected oestrus period, the gilts are moved to pens close to the service area and vaccinated. Two V boars are returned to the group for 24 hours only to stimulate the expected oestrus. From Monday onwards, gilts in pairs will be brought to serving pens to get nose-to-nose contact with boars. On the first day, gilts may be a little nervous so they are allowed a good minute to "stand and explore the boar." Standing oestrus is unlikely on this first day, so gilts will be returned to their group.

The following day, the same procedure - two gilts per operator - are run into the serving pens alongside the boars to check standing oestrus. Three operators are used to inseminate, so the system of running perhaps 120 gilts to serving pens takes around three hours.

This procedure will be repeated for the whole week at 24hr intervals. Each gilt served will receive two inseminations as a minimum and a third if she will stand. Served gilts are batched up into groups of 20 and an "entire" boar is run with the group to calm them down. Feed levels for the served gilts are kept at 2.5kg/head for five weeks when scanning takes place to confirm pregnancy. Feed levels will be reassessed according to condition.

What other "little gems" of information contribute to their success?

  • After 10-15 inseminations each, the operators take a few minutes break to prevent operator fatigue
  • A radio is provided for stock and operator contentment
  • The stored semen is turned three times/day
  • Sow catheters are used to get a better lock with less leakage
  • The gilt MUST stand to be inseminated with the inseminator mimicking boar stimulation
  • Be patient - allow time for gilts to settle and do not force the semen in
  • 16 hours of very bright white light is used to aid stimulation of oestrus
  • Remove any stress on the gilts for the five weeks following service

What impresses me is the dedicated attention to detail practiced by the staff which is achieving spectacularly consistent results.

Source: John Goss, PIC UK - December 2004

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