Boar breeding and reproduction

1. Breeding and Reproduction
Pastured pork production
Silvana Pietrosemoli
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Beginner Farmer Resources

2. Beginner Farmer Resources
Pig breeds for outdoor production
Important traits:
▪ Hardiness.
▪ Vitality and disease resistance
▪ Foraging ability
▪ Strong legs
▪ Quiet and docile temperament
▪ Meat quality
▪ Pigmented skin
▪ Modern genotypes vs Heritage breeds
▪ Pure vs crossbreed
Balance productivity, suitability to outdoor
condition and market preferences
Sows
Prolificacy
Good maternal instincts
Milk production
Good fat reserves
Ease of handling
Boars
Fertility
Good libido
Docile

3. Beginner Farmer Resources

4. Beginner Farmer Resources
Breeding boars should be kept separate from sows until they are about eight
months old.
Breeding pigs
Breeding methods
▪ Natural mating
Pasture mating: multiple boars are placed with groups of females. (15-20 sows/boar)
Pen mating: A single boar is placed with a group of females in a paddock. 10 sows/boar
Hand mating: Females in heat are taken to the boar pen or paddock.
▪ Artificial insemination
Feeding for reproduction
Increasing gilts/sows feed intake 10-14 d before mating increases reproduction rate
Amount of energy in the diet is important

5. Beginner Farmer Resources
The Boar
Extreme ambient temperatures affect semen quality
Frequency of use
▪ Once daily or four days/week
▪ Young boar should be used less
▪ Boars raised in groups attain puberty earlier, and have more aggressive libidos.
▪ Typical ratio is 20 sows/boar.
▪ Allow new boars two months to adjust to the new environment
▪ First mating with similar size females showing heat
Mating behavior
▪ Grunting, nuzzling, and chomping behaviors
▪ Foaming at mouth
▪ Using snout to check for standing hear
45 days are required from the start of production to ejaculation of sperm.
Cull out boars which are lame and/or have low libidos

6. Beginner Farmer Resources
Gilt or sow in heat
▪ Standing Reflex-Mounting other females and/or being mounted by other females
▪ Restless behavior/ decreased appetite
▪ Increased vocalizations, erect ears, tail upright
▪ Frequent urination
▪ Pink-red and swollen vulva, with sticky mucus discharge
Stimulating gilts and sow to come into heat
▪ Putting a gilt/sow which is in heat with those which are not
▪ Pen gilts/sows next to a boar so that they can see and smell
him.
▪ Simultaneously weaning a group of sows
Heat: last 8 to 36 hours.
repeats every 21 days.
Poor nutrition, health or housing conditions could result in reproductive problems
Sows come on heat again four to ten days after weaning

7. Beginner Farmer Resources
Gestation
Gestation 114 (111-120) d
Move the sows to the farrowing paddocks
5-7 d before the expected farrowing date
Approximate time before delivery Sow characteristics/ behavior
0-10 days Enlargement of the Mammary glands
0-10 days Swelling of the vulva
2 days Mammary glands become turgid and tense and secrete a clear fluid
12-24 hours Mammary glands begin to secrete milk
12-24 hours Overall restlessness, nesting behavior
6 hours Abundant milk secretion
30 minutes-4 hours Increased respiration
15-60 minutes Sow quiets and lies down on her side
30-90 minutes Straining, passage of blood tinged, oily fluid and meconium ( fetal feces)
Behavior of the pre-farrowing sow
Adapted from Singleton, Amass, Clark and Runnels, 1997
Provide nesting material

8. Beginner Farmer Resources
Farrowing
▪ Total time varies with litter size, 2.5 hrs.
(3 to 8 hrs.),
▪ Piglets every 10 to 20 min
▪ Placenta 2-4 hrs. after the last pig
Monitor the sow frequently over the next 24 hrs.
Caring for the newborn piglets
▪ Assure colostrum intake (Antibodies and high energy source)
▪ Satisfy piglets’ ambient temperature requirements (82 to 86 ° F)
Provide a dry, clean, well-bedded farrowing hut
Avoid drafts
Insulated boxes can work as nests
If possible provide supplemental heat
Process when the sow give birth to the piglets

9. Beginner Farmer Resources
For a good reproductive performance
▪ Maintain a disease-prevention program for the herd
▪ Treat sows for internal and external parasites before moving to farrowing paddock.
▪ Record breeding dates, calculate farrowing dates
▪ Move sows to the farrowing paddocks by the 110th day of gestation.
▪ Organize sow groups according to the
age/parity
▪ Stimulate estrous exposing females to
adult boars
▪ Conduct good estrous detection
▪ All newborn pigs should receive
colostrum
▪ Provide adequate housing
▪ Record sow productivity data to use
later in selection and culling.

10. Beginner Farmer Resources
Sows Body Condition Score and
litter size
All sows should be between BCS 3 and
3.5 at farrowing, and not less than BCS 2
at weaning
Sows Body Condition Score and litter size
“Only sows in good shape and with good
milk production will care best for the
piglets. Further on, a low weight loss in
lactation will lead to a higher litter size in
following cycle”.
Dr Gunner Sorensen,
Danish Agriculture and Food Council's Pig Research Centre

11. Beginner Farmer Resources
Heat stress impacts reproductive performance
▪ Heat stress can cause reproductive problems in both sows and boars
▪ Sows are especially sensitive 7-21 d after mating
▪ Farrowing rate and litter size could decline
To minimize heat impact
▪ Ensure water supply (drinking and
cooling)
▪ Provide shade (Natural or shades
structures)
▪ Provide ample space for lying
▪ Feed during the cooler time of the day

12. Beginner Farmer Resources
Reasons to cull sows
▪ Anoestrus- Not showing heat
▪ Failure to conceive (after two
failed attempts)
▪ Abortion
▪ Lameness
▪ Diseases
Poor performance
▪ Farrowing difficulties
▪ Poor litter size
▪ Poor lactation and rearing ability
▪ Poor maternal behaviour
▪ Decreased productivity compared
to the herd average.
How to reduce involuntary culling
▪ Selection for sow longevity
▪ Reduce body condition loss during lactation
▪ Body condition score sows
▪ Feed on a group basis after sorting by body
condition
▪ Consider a ‘skip-a-heat’ policy where appropriate
▪ Check legs and feet after each farrowing cycle

13. Beginner Farmer Resources
▪ Missed breeding
cycles
▪ Abortions
▪ Stillborns
▪ Mummified pigs
▪ Lightweight newborn
pigs
Diseases and Reproductive performance
▪ Porcine reproductive and respiratory syndrome PRRS
▪ Pseudorabies
▪ Parvovirus
▪ Erysipelas
▪ Leptospirosis