Getting pigs born alive and started right in the first few days of life can reasonably be called “risk management.”
It is estimated that any increase in survivability achieved by reduction of stillborn rate or preweaning mortality will improve cost of production by at least 50-60¢/pig.
Risk factors vary by farm, management style and, perhaps most importantly, with the level of staff training. The 12 risk factors that follow, and the management recommendations that address them, were compiled from controlled and in-field studies.
- Pigs born without supervision (during lunch break, at the end of the day, overnight)
Some studies show the stillbirth rate of unsupervised farrowings at twice the frequency as supervised farrowings (6% vs. 3%).
Further, when additional supervision was extended through the first three days of life, the risk of death fell from 1.29 pigs in unsupervised litters to 0.85 pigs in supervised litters.
The success of supervised farrowings is dependent on effective training of farrowing attendees, and whether sows were induced to farrow at a time when employees were available.
On farms where monitoring is available 24 hours a day, induction may not be necessary. However, when sows are induced to farrow, more pigs are available for crossfostering, farrowings can be timed to when supervision is available, and there is more opportunity to pre-plan other tasks in the farrowing barn.
Farrowing attendees can provide sows and pigs with extra individual care, such as:
Remove placental membranes to prevent suffocation;
Warm and dry newborn piglets (hot boxes, toweling, drying agents);
Give special care to lower viability pigs (extra heat, colostrum);
Practice split suckling of large litters;
Administer fluid to dehydrated pigs (orally or subcutaneously);
Tape the legs of splay-legged pigs;
Record natural farrowing interval of individual sows using monitoring cards;
Offer obstetrical assistance when farrowing interval exceeds normal farrowing interval for a sow;
Practice early crossfostering post colostral intake.
Additional tasks farrowing attendees can do:
Flag high-risk sows to increase observation;
Remove fecal material behind sows;
Shorten or tie navel cords;
Administer early treatments prescribed by veterinarian;
Ensure early colostral intake of all pigs via split suckling, syringe feeding or stomach tubing prior to crossfostering;
Walk farrowing crates the first three days to check for laid-ons, weak pigs, signs of illness in sows (mastitis, agalactia, infections);
Treat sows aggressive to pigs;
Stagger lunch breaks so someone is with farrowing sows at all times;
Late in the day, mark first born, so if pigs need to be crossfostered before staff leaves, they know which pigs most likely have had colostrum.
Timing of induction is the key to optimizing the viability of the pigs and the number of sows farrowing during the day. It is recommended that induction be based on the average gestation length of the herd.
- Born to high-risk sows
Higher stillborn rates in litters from older sows are well-documented.
In the mid-'80s, research by Tim Blackwell, DVM, showed the risk of stillborns in Parities 1 and 2 at 15%, Parities 3 and 4 at 25%, Parities 5 and 6 at 35%, and Parities 7 and higher at 45%.
Some farrowing managers choose to only induce and monitor high-risk sows (Parity 4 and higher), thin or obese sows, or sows with a history of stillborns. It is helpful to flag high- risk sows as rooms are loaded or at induction.
Attendees must understand that if a sow is synchronized with oxytocin 20-24 hours post-induction, increased vigilance is necessary to ensure the sow is provided wise obstetrical intervention (vaginal palpation; udder stimulation; oxytocin administration) when farrowing interval is excessive.
Obese sows have more prolonged labors, which can lead to increased stillbirths. Conversely, backfat levels below optimal body condition may cause decreases in hemoglobin and, thus, an increase in stillborn rate.
Tools like flank-to-flank measurements and body condition scoring guides can help address sows that are over- or under-conditioned.
Other tools include adjusting gestation feed intake according to metabolizable energy (ME), monitoring and adjusting feed drops regularly and sow weight, as estimated by girth measurements.
Good management of sow body condition is a great way for the breeding /gestation team to help lower stillborn rates.
- Born late
Being born late in the farrowing process is risky. There is greater risk of hypoxia and delayed delivery. Vaginal palpation, udder massage, and/or administering 5-20 IU of oxytocin, if contractions are weak or lacking, may be necessary to help expel the last pigs to be born.
But before offering obstetrical assistance, consider the intervals between births, sow parity and the size of the litter.
Normal interval between pig births is 20-30 minutes, but ranges from 15 minutes to several hours. If you can document a sow's natural farrowing interval, when she exceeds her normal interval by 10 minutes, intervention via vaginal palpation is warranted.
Natural oxytocin release by the pituitary gland can occur by stimulation of the udder, by vaginal palpation or by keeping at least four pigs nursing at one time. If the farrowing process slows towards the end, stimulation of the udder alone, or with vaginal palpation, may help.
If these attempts fail, the sow may be hypocalcemic and may benefit from an intramuscular injection of calcium. Research has shown that plasma concentrations less than 6mg/100ml were associated with reduced uterine activity during parturition.
Calcium is a very important part of the parturition event. Release of intracellular calcium is necessary for the contraction of the uterus. A difficult or long labor, or one where excessive oxytocin is used, can predispose a sow to becoming hypocalcemic.
- Born in a large litter
Studies have shown that in litters of more than 12, the likelihood of being stillborn doubles. As genetic selection increases litter size, management efforts to minimize stillborn rates will be critical.
Sows with a history of large litters should be flagged to ensure those farrowings are attended.
Pigs in large litters have a higher risk of insufficient colostral intake. Split suckling can help ensure pigs obtain adequate colostrum within the first 12 hours. Then, in the next 12 hours, pigs can be crossfostered, taking into account the location of smaller pigs.
- Overuse or misuse of oxytocin
Oxytocin may reduce time of labor by almost half, increase the strength of uterine contractions and help coordinate farrowing time to fit staffing schedules. However, recent research has shown that the negative effects of oxytocin administration to “synchronize” sows to farrow, and excessive or early administration of oxytocin, can have negative effects on the sow and unborn piglets.
Negative effects include increased myocardial contraction of unborn piglets, decreased fetal cardiac frequency, increased hypoxia of piglets, increased intra-partum stillbirths, increased number of piglets with severe meconium staining, increased number of ruptured umbilical cords, increased stillbirths and increased chance of a sow becoming hypocalcemic due to the intensity and frequency of uterine contractions.
When employees hear these risks, their first instinct is to eliminate oxytocin from the program, but remember, we are managing risk. Sometimes we have to take a risk to manage a risk.
The combination of PGF(2alpha) and oxytocin can cause increased number of stillborns compared to other induction methods, but increased monitoring of sows at farrowing can offset this effect.
It is essential that every farm has very clear standard operating procedures for dosage, timing and route of administration of oxytocin to quell indiscriminate use and over-dosage. Oxytocin can be a valuable tool used during judicious obstetrical assistance, if used in moderation and with caution.
- Prolonged labor
Prolonged labor can be instigated by disease, calcium and/or phosphorus deficiency, anemia in sows, large litters, induced hypocalcemia and later parity. But each is correctable and preventable.
The use of oxytocin to synchronize farrowing can speed up the birthing process, however, the negative effects listed in risk factor #5 should be considered.
- Born to a stressed sow
Stresses can cause the sow to release stress-related hormones, such as epinephrine (adrenaline), and move her into fight-or-flight mode. When adrenaline is released, the hormones regulating the farrowing process lower the sow's ability to deal with the offending stressor.
Common stressors include pig processing or loud, abrasive behavior by staff while sows are farrowing, or the presence of an employee that the sow “dislikes.”
To promote a calm environment and to alert staff that this is a room where calm, quiet behavior is necessary, it is helpful to work with the lights off. Sows prefer to farrow at night, so why not simulate night?
Sows experiencing heat stress ranging from mildly high temperatures (73-77°F) to very hot temperatures (over 77°F) are at risk for increased stillbirths due to prolonged labor, epinephrine release, hypoxia, hypocalcemia, etc. More than 40 breaths/minute is often considered heat stressed.
The optimal temperature for the sow to farrow and lactate is about 65°F. Since the newborn pig's optimal environmental temperature is 93°F, we usually compromise and set room temperatures at 70-74°F. If baby pigs are dried shortly after birth and provided with adequate localized heat, room temperatures can be set at the lower end of the range for the sows' sake.
- Vaginal palpation
Vaginal palpation or “sleeving” can be a valuable tool to reduce stillborn rates, but if done without reason or proper skills, it can have negative effects, too.
Even when done with reason, sleeving has a risk of increasing stillborns. Therefore, sows that have been “sleeved” once need increased vigilance and may need to be sleeved again to prevent more stillborns. It is another take-a-risk-to-lower-a-risk situation.
Good hygiene and a clean, well-lubricated, disposable sleeve are essential. A monitoring card will help track a sow's natural farrowing interval and recognize whether vaginal palpation is warranted.
- Born hypoxic (oxygen-starved)
Low doses of oxytocin can help avoid a slowdown in cardiac frequencies in the fetus, rupture of the umbilical cord and meconium staining; it does not reduce the fetal mortality rate, but may increase the viability of the newborn piglet.
An oxygen-starved pig has a higher risk of being weak, not getting enough colostrum and being laid on. Proper oxytocin use and how to resuscitate a baby pig born severely hypoxic must be a part of every farm's training.
- No colostrum or inadequate colostrum
Colostrum is one of the most important substances a pig receives in its life. It is a prerequisite for high health and low mortality from birth to slaughter.
A pig's ability to absorb adequate amounts of colostrum depends on the amount consumed, the immunoglobulins (IgG) concentration, the timing of consumption in relation to intestinal closure, the teat nursed, competition between piglets and birth weight.
A sow's colostrum production is independent of litter size or parity. Some feel it serves as “a good marker for the maternal quality of the sow.”
Studies have shown that most pigs consume twice the amount of colostrum needed by 12 hours after birth. The smallest pigs, however, take 16-24 hours unless you intervene with split suckling. If you do not split suckle, this restricts crossfostering opportunities to 12 hours for the medium to large pigs and 16-24 hours for the smaller pigs.
Since it is best to crossfoster pigs before the 24-hour mark due to teat territorialism and sow bonding with pigs, split suckling is a valuable tool for speeding up colostrum intake in small and late-born pigs.
Another consideration associated with split suckling is that the ability of antibody proteins to move through the pig's gut decreases with time and the stimulus for these “holes” to shut down is the presence of milk in the gut. IgG intestinal closure is typically complete by 18 hours, post birth.
Stomach tubing or bottle feeding of the sow's colostrum — or cow colostrum used as a substitute — has helped start small pigs that have not received adequate colostrum.
- Born to a sow that had a tough labor (born later or last)
Pigs born to a sow with a prolonged labor is at greater risk of anoxia — abnormally low oxygen levels. One study shows that when farrowing takes over six hours, the mortality rate is 21% compared to just under 12% for litters farrowed in less than six hours.
Judicious obstetrical assistance and ensuring newborns receive colostrum within 12 hours is a great help.
Others use this risk as a reason to continue to synchronize sows to farrow with oxytocin, regardless of her being a high or low-risk sow. It is yet another way to manage a risk with something that has a risk.
- Not establishing cross-fostering guidelines
It is important to develop early crossfostering principles that have a purpose. Large litters and light birth weights are the most obvious reasons to move pigs. Since pigs adapt quicker to a new teat when moved at a very young age, it makes sense to move them as soon as possible after colostral intake is ensured.
The philosophy, less is more, may be the best guidance when establishing crossfostering protocols:
Minimize stress by crossfostering within the first 24 hours after birth.
Count functional teats to determine sow's rearing capacity.
Consider teat size and functionality.
Transfer either the smallest or largest pigs from a litter to minimize movement.
Small pigs are at greatest risk of not establishing teat fidelity. Studies have shown that small pigs have consumed enough colostrum, but they subsequently died from lack of energy — probably because they lost the battle for an available teat.
Moving small pigs to a milk deck may be cost effective.
Whoever does the crossfostering must be well trained, a good thinker and a quick decision maker.
*Condensed from a 2007 American Association of Swine Veterinarians preconference workshop presented by Sarah Probst-Miller, DVM, Carthage (IL) Veterinary Service; the complete paper is posted at: www.hogvet.com/cvs/articles/Day1CriticalCare.pdf.