Practice Tip (Non-Refereed)

Gilt management during acclimatization

Laura Batista, DVM

College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota 55108.

In recent years, new diseases such as
PRRS have caused the swine industry
to change its gilt acclimatization strategies, for example,

• Implementation of a quarantine and gilt management area,
• Fewer introductions per year,
• Introduction of more gilts per group,
• Introduction of gilts of different ages and weights per group.

In systems receiving 400 to 500 gilts per group, adequate management is essential. A farm that expects to wean 24 pigs per sow per year must follow a strict management protocol during quarantine and acclimatization. I have found the following protocol helpful.

Sort gilts on arrival and keep records by pens

Sort gilts by age and weight and, if possible, by genetic line as soon as they arrive. Provide the isolation unit manager with a daily updated spreadsheet containing

• Pen ID
• Gilt ID per pen
• Age and approximate weigh of each gilt
• Starting heat check date for each pen
• Maximum age to reach puberty for each gilt
• Date for intervention for a gilt that does not show heat at the maximum date permitted
• Type of intervention(s)
• First date of estrus presentation for each animal in the unit
• Consecutive heat dates
• Others (eg, seminal plasma application, vaccination(s) dates)

Stimulate early onset of puberty

Heat checks should start 1 week after arrival for gilts over 135 days of age. There is no benefit from stimulating younger gilts. Although few gilts will respond to boar stimulation at 130 to 140 days of age, those that do are the most fertile and will cycle more regularly, have larger litters, and live longer. Stimulating early onset of puberty does not imply that gilts should be bred at an early age or light weight. Gilts should be 220 to 240 days of age and weigh 130 to 140 kg (286 to 308 lbs) at the first breeding or insemination.

Vasectomized boars aid in stimulating and detecting estrus. Heat check by providing one mature, vasectomized boar for every eight to 10 gilts in the pen, and allow boars and gilts to be in contact for at least 10 to 15 minutes.

Organize the gilt pool

Gilts that show estrus in any week should be regrouped into one pen. In a few weeks, there will be an organized gilt pool, and only the pen(s) due to come in heat each week and some delayed animals will need to be heat checked. This provides for better reproductive and general management of the unit. In addition, there will be a pool of cyclic gilts from which replacements can be drawn. In conjunction with a Replacement Monitor, having an organized gilt pool ensures that weekly mating targets are met. When gilts are penned by week of estrus, the time from each gilt's entry into the isolation unit to her first service will be reduced, which in turn reduces non-productive days. Most gilts can be bred at the third estrus, rather than second, as is desirable. Lastly, gilt selection can be completed before the gilts reach a market weight of 115 to 120 kg (253 to 264 lbs), so that cull gilts can be sent to slaughter rather than being sold as cull gilts at a discount.

Gilts ready to be bred should be moved to the Breeding Area at least one estrus before the target AI or breeding. Late movement or transportation will reduce feed intake, resulting in a lower ovulation rate and increased embryo mortality.