Timing Induced Farrowings The practice of induced farrowings has been used on hog farms for more than 15 years. It is still widely used to increase survivability in the farrowing crate.
Induced farrowings are accomplished with the use of an injectable prostaglandin and followed with an injection of oxytocin 25 hours later to all sows that haven't farrowed.
The prostaglandin should be given 72 hours before farrowing, but not before day 111 of gestation.
There are two products available: Lutalyse from Pharmacia & Upjohn and Estrumate by Bayer Animal Health. Lutalyse is the only prostaglandin approved for use in swine; both require a veterinary prescription.
The farrowing pattern seen following prostaglandin induction is generally: 3-5% farrow within 12 hours; 20% farrow between 12-24 hours; 65-70% farrow between 24-36 hours.
Induced farrowing helps increase farm output in many ways. It results in predictable farrowings, allowing farm personnel to aid in farrowings and reduce stillborns. Also, a regimented induction program will group farrowings to create a more uniform weaning age and ease crossfostering. Litters can be processed in larger groups more efficiently.
Trial data indicates farms may see up to 0.5 extra pigs by attending farrowings. A farm averaging 2.2 litters/sow/year could see 1.1 extra pigs/sow/year. That 1.1 extra pigs at weaning adds $33, assuming a weaned pig is worth $30. An induced farrowing program will cost about $2 per sow (2.2 litters/year), a benefit-to-cost ratio of 16:1.
Two problems occur with improperly induced farrowings. First, sows must be at least 111 days of gestation to avoid premature pigs. Premature pigs lead to higher death loss in the farrowing crate.
The second problem occurs with the improper use of oxytocin. When given too soon, oxytocin can cause poor uterine contractions, increasing stillborns. Oxytocin must be given at least 25 hours after the prostaglandin injection. The sow should show a clear vaginal discharge and have milk in her udder, which is easily expressed. The dose must not exceed 1cc.
The staff should also take precautions when using prostaglandins. It can be absorbed through the skin. Women of childbearing age, asthmatics and persons with respiratory problems should avoid contact or wear disposable plastic gloves when administering the product. Some farms forbid women from handling prostaglandin.
Case Study No. 1 Farrowing performance in a 1,200-sow, feeder pig-producing herd had an average preweaning mortality of 11%, about average in the industry. Over the past six months, preweaning mortality has averaged 13.5%.
The farm uses prostaglandins to induce sows that have not farrowed by day 115 of gestation. Recently, they moved to a program of injecting all sows at 111 days of gestation or greater on Tuesdays or Thursdays. The goal is for most sows to farrow on Wednesdays and Fridays. This allows the farms to attend farrowings and process larger numbers of litters together.
Since the program started, preweaning mortality actually increased. Records showed a decrease in birth weight and a decline in the average herd gestation length.
We directed the farrowing manager to write the 111-day date on each farrowing card. Our goal was to ensure that no prostaglandin injections were given early. This method worked. Preweaning mortality returned to 11%.
Case Study No. 2 A 180-sow, farrow-to-finish farm farrows on a four-group, five-week system. The owner does the majority of the work, prefers morning farrowings so he can attend while doing feeding and processing.
Typically, he would inject sows with prostaglandin when finished with the morning chores and inject with oxytocin first thing the next morning. This would allow him to observe and assist any sows that had difficulty farrowing.
Shortly after starting this program, he complained about a high level of stillborns and increased farrowing problems. We reviewed his protocol and stressed the importance of waiting 25 hours after the prostaglandin injection before giving the oxytocin. On the next farrowing group, he made this adjustment and the sows responded to the oxytocin in a much more predictable fashion. Sows started to farrow as expected and needed only occasional assistance.
Induced farrowings can be a useful tool to increase pigs weaned but it is not for everybody. If your current stillborn rate is under 5% and prewean mortality is under 8%, you may not see a return from increased production. But there may be advantages from a labor/management standpoint.
Farrowing induction must be looked at on a farm-to-farm basis and only used with a specific purpose or goal in mind. The results must be evaluated to determine if the desired response is seen.
Develop a set protocol, day of week and targeted sows to be treated, and when and if oxytocin should be used.
Review the protocol with the veterinarian, farrowing manager and staff to be sure everyone understands it.
