Swine Management: Replacement Gilts and Breeding

Management of the Replacement Gilt

• Replacement gilts require a diet similar to fattening pigs, transitioning to a developer diet around 4 months old (70 kg) to address potential leg weakness.
• Leg weakness in gilts can impact breeding potential; nutrition is critical for their reproductive performance.
• Selection criteria for replacement gilts include growth rate, body conformation, and importantly, fertility status, which influences litter size and piglet weight.

Boar Exposure and Estrus

• Introducing a boar to a 135-day-old replacement gilt daily can trigger estrus in approximately 61% of gilts within 4 weeks.
• Ideal mating age for gilts is 7 months at weights of 120-140 kg; boars should be at least 10 months old with visible signs of aggressiveness.
• Gils exposed to boars earlier (135 days) show improved estrus manifestation; however, 50% may not have a successful second estrus if exposure occurs later.

Feeding and Management on Arrival

• Maintain the gilt's original feed to mitigate stress from dietary changes upon arrival at a new farm.
• Target back fat thickness during the first mating should be between 16-18 mm; regular contact with boars is crucial in the first 48 hours after arrival.

Features of an Ideal Breeder Gilt

• Effective breeder gilts should ideally rear a high number of piglets annually (PWSY).
• Factors influencing reproductive success include boar age, health, environmental conditions during breeding, and a high-quality diet rich in protein and minerals.
• Boars aged 12-18 months should be utilized 2-3 times weekly, while those aged 18-30 months can be used 5-7 times, ensuring semen quality through proper breeding schedules.

Breeding Management

• Breed sows ideally before 7:00 AM or after 4:00 PM to avoid increased heat stress during midday.
• Quality of semen is crucial; a minimum volume of 150 ml and a sperm count of at least 350 million sperm/ml are essential.
• Regular checks on semen count and motility enhance the likelihood of successful fertilization.

Insemination Techniques

• Apply slight pressure to the sow or gilt's back to secure catheter placement during artificial insemination, improving sperm delivery success rates (FR of 85%, CR of 98%).
• A saddle or AI dummy can aid in maintaining proper catheter position.

Parity and Genetic Value

• Maintaining an average sow parity (ASP) of 3-4 optimizes genetic potential; a distribution of 47% of sows in parities 3-5 is desirable for generating heavier piglets.
• A specific farm example shows an ASP of 3.23, indicating balanced productivity among newer sows.

Sperm Quality and Timing

• Successful fertilization is impaired by poor semen quality; aim for a sperm motility rate exceeding 90% for efficient fertilization.
• Breeding should occur on the second day of estrus, with follow-up checks after 6-12 hours post heat detection.

Mycotoxin Management

• Aflatoxin in feeds can induce infertility; monitor feed moisture levels (below 13%) for safety.
• Zearalenone exposure during early gestation can lead to increased embryonic mortality.

Pregnancy Care

• Pregnancy failures typically observed around Day 35 may result from reabsorption; effective breeding requires careful management of gestation practices and environment.
• Community pens improve fertilization success by ensuring better heat detection and breeding management before transferring sows to gestation stalls.

Nutritional Requirements

• Gestating animals need increased water intake (2.5 times dry matter intake) to support fetal growth and avoid complications during farrowing.
• Balanced nutrition is vital throughout gestation to ensure optimal body condition and fetal development.