Is an 18 day treatment regime which will bring gilts into heat within 5-7 days after the end of the treatment, thus facilitating heat synchronisation and batch management.

ALTRESYN suppresses oestrus during the whole of the treatment, which in turn enables:

  • Scheduled reproduction
  • Optimised productivity
  • Improved pig flow and herd health

ALTRESYN is an 18 day treatment regime which will bring gilts into heat within 5-7 days after the end of the treatment, thus facilitating heat synchronisation and batch management.

On a farm without ALTRESYN:

  • Depends strictly on nature for sequencing reeding and farrowing schedules.
  • Continually checking for oestrus.
  • Insemination at varying times.
  • Therefore need manpower available seven days a week.

On a farm with ALTRESYN:

  • More efficient breeding.
  • More efficient gilt pool management.
  • More efficient use of labour.
  • More predictable pig flow.

Synchronisation of oestrus in gilts

Treatment with ALTRESYN can be started at any stage of the gilt's oestrus cycle:

Regardless of the stage of the oestrus cycle when you start administering ALTRESYN gilts will come into oestrus simultaneously within 5-7 days after the treatment.

The ALTRESYN treatment period is fixed at 18 days to cover the whole luteal phase, even if the treatment has started in the follicular phase. At the time of ALTRESYN withdrawal, all gilts are at the same physiological stage. Follicular growth will start again after the break in inhibition of gonadotropin hormones associated with the withdrawal of ALTRESYN. The follicular phases of all gilts receiving the treatment will be synchronised and oestrus will appear with ovulation over the next 5-7 days.

The Danish Experience1,2 with ALTRESYN

A recent study1,2 performed in Denmark on a farm unit of 1170 sows with weekly batch management using ALTRESYN to synchronise gilts demonstrated outstanding results in terms of:

  • Better flow of breeding animals.
  • More homogenous batches.
  • Increased output of weaned piglets.
  • Significant saving in feed costs.

Synchronisation of oestrus

Farrowings of 42 batches with synchronised gilts were compared with a previous 40 batches, when gilts were inseminated during the 2nd spontaneous heat.

Out of the 816 gilts treated with ALTRESYN, 758 were successfully mated (93%) with high rate of synchronisation.

89.7% of gilts were mated between 6 and 8 days after treatment.

Better distribution of age at first service and reduction of overall feed costs in gilts

Reduction of the average mating age in the gilts per year by 18 days (from 259 to 240). A saving of £10 - £15 of feed per gilt/year.

The distribution of the age at first service was more preferable after the synchronisation with less matings of older gilts.

Reduction of variability for mated gilts and sows

The number of gilts inseminated each week increased from 13.2 to 15.3 (p<0.05) and the variability within weeks decreased significantly (p<0.0001). There was also a significantly lower variance in the number of sows and gilts served during a week after synchronisation compared to before (p<0.005).

More number of farrowings

As a result the weekly number of farrowings increased from 50.8 to 53.5 (p<0.05) and became more even as well (p<0.05).

More weekly weaned piglets on average

Better filled farrowing rooms with a more predictable number of piglets resulted in an increase in the average number of piglets weaned each week (p>0.05). The reproductive performance of P1 sows treated as gilts with ALTRESYN was similar to the previous year with no synchronisation, with the conception rate of 92.1% and a WOI of 5.3 days compared to previous results of 91.4% and 7.8 days.


  • 1. Instructions of use

Attach the doser and tube to the bottle, which releases an exact dose of 5 ml (20 mg altrenogest) per gilt.

  • 2. Individual dose is best

Using the ALTRESYN doser syringe administer 5 ml /gilt /day for 18 consecutive days. Only administer to cycling gilts that have shown a 1st heat.

  • 3. Timing

Make sure the gilts receive their individual dose of ALTRESYN at the same time every day (+/- 15 min).

  • 4. Duration of treatment

ALTRESYN must be administered each day of treatment:

18 days for nulliparous gilts.

If you stop using it for even one day, effectiveness may decline.

  • 5. Gilt management post day 18 of treatment

It is essential to set the date of mating - 6 days post ALTRESYN treatment.

(Usually coincides with serving the weaned sows).


1. G. Sørenson (2013), Best practice in the gilt unit. Congress for pig producers. Herning 2013.

2. N. Thing et al. (2014), New ways to evaluate the benefit of gilts synchronised by ALTRESYN on the flow of breeding anmals and the piglet output. ESPHM Proceedings 2014

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