Pig Reproductive Management

Pig reproductive management the sow during gestation, farrowing, and lactation is a means to reach a goal. A large litter of healthy pigs at birth that will remain healthy and grow rapidly. Care during this time must also prepare the sow for a successful repeat performance at the earliest time within the system of weaning and re-breeding used. The sow must reach farrowing in the best nutritional and microbiological health for herself and the expected litter. Properly balanced rations should be fed in recommended amounts so that newborn pigs are well developed and strong. A herd health program that assures minimal exposure of the sow to disease or disease carriers during gestation is essential for maximal litter survival during the first weeks of life and for effective growth to weaning and market. The sows should be managed in a gentle and confident manner and on a regular daily schedule.

Pig Reproductive Management: Boar Selection

  • The boars have more impact than the females. Select wisely and carefully.
  • Concentrate on performance trait(s) of economic importance and select from source that test or record as many boars as possible (high selection intensity)
  • Make certain only healthy replacements selected. This is especially critical if boars are purchased.
  • Select for physical soundness: strong feet and legs, watch them walk, no buckling of front legs or stiffness in hind. Boar must have good general conformation and willingness to breed (good libido).

Pig Reproductive Management: Boar Management

  • Feed to keep fit, not fat, usually receive sow gestating diet;
  • If purchased, isolate for 3-6 weeks, allow 3-4 weeks to settle in;
  • Can use to breed at 6-7 months of age – occasional service;
  • Ensure that first mating is successful. Use a small, quiet sow or gilt in good estrus.
  • Mating in boar’s pen may be the best location since the male is not distracted by new surroundings.
  • Wait until 7-8 months of age before regular use, 2-4 times per week until one year of age.
  • Mature boars can perform 6-10 services per week.

Boar to Sow-Gilt Ratios

Natural service – 1 boar for every 20 females

AI + natural – 1 boar for every 20-30 females

All AI – 1 boar for every 40-50 females. Larger herds require fewer boar’s

Factors Influencing Puberty

Genetics
– Yorkshire and Landrace usually mature slightly earlier than Hampshire or Duroc.
– crossbreeding advances puberty.

Nutrition
– restricted feed intake can delay puberty slightly.
recommend to allow only 0.5 kg gain per day after market weight.
– obesity interferes with normal ovarian function.

Distress
– moving or mixing gilts – fight
– tends to cause puberty 4-7 days later
– contact with boars may advance puberty
– related to pheromones
– direct exposure most effective
– exposure should not be too early (after 155 days of age)
– older boars more effective.

Light
– some evidence for advantage of increase light
– may decrease age at puberty
– may increase litter size

When to mate

  • litter size related to number of heats more than age or weight
  • fewest ova at first estrus (heat) = smallest potential litter
  • increase by about 1 ovum each for 2nd, 3rd heat so potential litter size increases
  • normally breed in 2nd or 3rd heat so gilts farrow by 10-11 months of age.

Timing & number of services

  • Ovulation occurs about 36-40 hours after the beginning of standing heat
  • Optimum insemination is 6-12 hours prior to ovulation
  • Therefore, mate 24 hours after initiation of standing heat and rebreed 8-16 hours later if female will still accept the boar or is still showing a positive (standing) response to the Back Pressure Test.
  • A different boar might be used at each service if breeding only for market pigs.

Pig Reproductive Management: Pre-farrowing

De-worming Sows. If there is indication of worm infestation, sows should be de-wormed about two weeks before moving to farrowing crates or pens. Treatment for external parasites at least twice (in approved repeat times for the product used) also should be accomplished within a few days before movement to the farrowing facility.

Preparing the Farrowing Unit. If possible, the total farrowing unit should be cleaned completely of organic matter, disinfected, and left unused for 5-7 days before a new group of sows is placed in the unit. When this is not practical, at least the individual pen, stall, or crate should be completely cleaned of organic matter and disinfected before a new sow is placed in the unit. Disinfectants are ineffective unless the cleaning job is complete. There are many good disinfectants available, including the quaternary ammonium compounds, iodoform compounds and others such as lye, to use when the cleaning job is done well. Some disinfectants such as those that contain coal tars or lye should be thoroughly rinsed off after several hours, especially from surfaces having direct contact with pigs.

Washing the Sow. Before the sow is placed in the farrowing pen, wash the teats and belly with mild soap and warm water. This will eliminate soil and fecal material that may contain numerous bacteria that are potential diarrhea-producing agents for the nursing pigs. This procedure will also eliminate ascaris (roundworm) eggs that would serve as a source of infection to the nursing pig.

Feeding the Sow. During pre-farrow in the facility, sows can be fed as they have been during gestation, that is limit fed 4-6lb./day depending on weather and housing conditions. Better results are often reported by producers, however, from feeding a laxative ration pre-farrowing to preventing constipation. Constipation can be prevented or corrected by changing to a bulky diet, by addition of 20lb./ton of epsom salts or 15lb./ton of potassium chloride, by use of linseed meal as part of the protein in the ration, or by use of other laxative ingredients. Oats or wheat bran may be used as 25% of the grain to create a bulky ration; in some areas, other fibrous feeds such as alfalfa meal or beet pulp may be preferred. Remove bulky ingredients from the sow ration soon after farrowing. Water should be freely available, but spillage that could cause wetness of the pen should be prevented.

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