Problem Solving - Litter Size

A high average litter size at weaning is critical to achieving optimum output from the breeding herd. It is equally important that these weaner pigs have grown well during the lactation as weaning weight largely determines post-weaning growth performance. With the modern high litter size genotypes we have the opportunity to achieve exceptionally high litter sizes at weaning, but this still requires that we manage the gilt/sow well from before breeding right through to weaning.

Focus Areas

With modern hyperprolific genotypes a reasonable target for litter size total born – i.e. including stillborn & mummified piglets - is 14.5.

This target varies with parity, gilts aiming at 13.0, parity 1 sows at 14.0 & all other sows 15+.

Causes Solutions
Poor lactation feeding
  1. Check lactation feeding of sows
  2. Increase feeding frequency
  3. Ensure water flow rate of at least 2L/min.
  4. Keep farrowing house temperature below 24°C
  5. Consider using pelleted feed if not doing so
  6. Try top-dressing with a mixture of sugars (e.g. sucrose & dextrose) in the last 7-10 days of the lactation. Note – this may be particularly useful for sows after weaning their first 2 litters.
Poor sow condition at weaning
  1. Ensure sows lose less than 8% of body weight during lactation
  2. If condition loss is excessive review lactation feeding of sows & consider the use of split weaning
Inadequate feeding pre-breeding
  1. Ensure gilts are fed at least 3kg/day of a gilt developer or lactating sow diet for a minimum of 2 weeks before breeding
  2. Ensure sows are fed at least 3kg/day of a lactating sow diet from weaning to breeding
Poor gilt management
  1. Mate gilts at second not first (pubertal) heat
  2. Ensure gilts are mated with a vasectomised boar at puberty
Breeding 7-12 days after weaning
  1. To avoid this try to increase lactation feeding of sows or consider split weaning
  2. If these fail consider treating sows with PG600 at weaning or Regumate for 5-7 days post-weaning
  3. If all the above fail consider using skip‑a‑heat breeding
Poor breeding management
  1. Review heat detection procedures & natural mating & artificial insemination protocols.
Stress in early pregnancy
  1. Avoid mixing & exposure to extremes of temperature in the first 2-3 weeks of pregnancy
Incorrect pregnancy feeding
  1. Feed gilts 2.4-2.8kg/day of a gilt developer or dry sow diet during the first 2-3 weeks of pregnancy
  2. Feed sows 2.3-2.5kg/day of a dry sow diet during the first 2-3 weeks of pregnancy
Poor herd parity distribution
  1. Aim for a parity distribution of approximately 20% gilts, 17% parity 1 sows, 15% parity 2 sows, 14% parity 3 sows, 13% parity 4 sows, 11% parity 5 sows & 10% parity 6 sows if culling on age after 6 parities. Adjust these proportions appropriately if culling after 7 or 8 parities.

With modern hyperprolific genotypes & a target for stillbirths + mummies of less than 6%, a reasonable target for litter size born alive is 13.6. This target varies with parity, gilts aiming at 12.2, parity 1 sows at 13.2 & all other sows 14.1.

For causes of, & solutions to, low litter size born alive look up litter size total born, stillbirths & mummies.

Virtually all piglets born dead were alive when the farrowing began. They die because they are queuing up to be born & lose or partially lose their oxygen supply as a result of stretching & uterine contractions.

Thus it should be possible with good farrowing management to speed up & assist the process & reduce these losses to 5%. Indeed, in countries where low cost labour is available, it has been shown that this figure can be reduced even further.

Causes Solutions
Large litter size
  1. While this is a good problem to have, you may assist the sow using farrowing induction & then ensuring staff are present to follow an attended farrowing strategy
Long interval between deliveries
  1. If this interval exceeds 20 minutes manually stimulate the vagina to release oxytocin. If this doesn't result in a birth within 10 minutes conduct an internal examination. If a piglet is blocking birth manually deliver it, if no piglet is blocking treat the sow with oxytocin
Long farrowing
  1. If farrowing exceeds 5 hours inject sow every 20 minutes with oxytocin until farrowing is complete then mark her for culling at weaning
High piglet birthweight
  1. Use farrowing induction & then ensuring staff are present to follow an attended farrowing strategy
Old sows
  1. The use of farrowing induction & an attended farrowing strategy is particularly beneficial for sows of parity 5 & above
  2. Old sows that have more than 3 stillborn piglets in a litter of less than 10 born alive should be culled
Seasonal factors
  1. Ensure farrowing house temperature doesn't exceed 27°C & that adequate ventilation is provided
Mummies (mummified piglets) are those piglets that have died during the foetal stage of the pregnancy – i.e. day 35 post-breeding onwards. They can be simply due to being in a large litter or may reflect the influence of stress or infection during the pregnancy. In normal circumstances they will be very few in number, although in cases of infection they can be considerable over short time periods.
Causes Solutions
Large litter size
  1. Where litter size is very large in mid pregnancy it is common for one or more foetuses to die. There is little that can be done about this in practice.
Stress in pregnancy
  1. Avoid exposing sows to extreme stressors such as major temperature variations or sunburn during mid- to late pregnancy
Infection during pregnancy
  1. Consult a veterinarian
It is rarely possible to save more than 90-95% of piglets born alive in a litter, particularly as some will be born with very low birthweights or low vigour. It is equally difficult to prevent all piglet deaths due to overlying by the sow. Hence, a realistic target of 9% is set here. In countries where low cost labour is available, it has been shown that this figure can be reduced even further.
Causes Solutions
Overlying by the sow
  1. Use a farrowing crate, preferably fitted with additional safety features such as a farrowing cradle
  2. Ensure the creep area is wide enough to prevent huddling piglets from straying into the danger area under the sow
  3. Use a non-slip floor in the farrowing pen & keep room temperature at 18-24°C
Savaging by the mother
  1. Use a farrowing crate to minimise the mother's access to the litter
  2. This is mainly a gilt problem so supervise them during & immediately after farrowing
  3. If necessary treat a savaging sow with a tranquilliser, but be prepared to remove the litter if savaging persists
  4. Consider muzzling savaging sows
Inadequate piglet nutrition
  1. Check the sow for mastitis
  2. Ensure all the sow's udder is accessible to the litter
  3. Assist weak piglets to suckle
  4. Consider using shift suckling at 2-3 hours after the farrowing has been completed. This involves removing the heavier half of the litter (check they have full bellies) from the sow & placing them in a warm location (e.g. a plastic box inside the farrowing pen) for 1-1.5 hours. This then allows the weaker piglets free access to the udder & colostrum.
Chilling of piglets
  1. Maintain farrowing house temperature at 18-24°C
  2. Use overhead heaters (hovers) or heat pads in the creep area
  3. During farrowing place an overhead heater above the birth site
  4. Minimise drafts, particularly in the creep area
Piglet disease
  1. Ensure good farrowing house hygiene
  2. Implement an appropriate sow vaccination program
  3. Ensure all piglets get adequate colostrum – if necessary use shift suckling
  4. Treat struggling piglets with exogenous immunoglobulins
  5. Treat infected piglets therapeutically (consult your veterinarian).
With modern hyperprolific genotypes & targets for litter size (total born), stillbirths + mummies, litter size (born alive) & pre-weaning mortality of 14.5, less than 6%, 13.8 & 9% respectively, the target for litter size weaned is 12.5. This target varies with parity, gilts aiming at 11.0, parity 1 sows at 11.9 & all other sows 12.7. For causes of, & solutions to, low litter size weaned look up litter size total born, stillbirths, mummies & pre-weaning mortality.