Regarding the reproductive failures in pig production, we should be aware that the profitability of pig farming is determined to a large extent by the reproductive performance that’s number of piglets born alive / sow / year. This is governed by two factors; litter size and number of litters each produces each year.
Gestation length =114 days.
Lactation length = 28 days.
Weaning to oestrus = 8days.
Total = 150 days.
Potential = 2.4 litters/sow/year.
Average piglets born alive per litter 14. Therefore, number of piglets / sow / years = 28.
Infectious diseases can play a role in reproductive failure but there is a tendency to blame them for everything. Many microorganisms cause reproductive failure in pigs. However, it is frequently hard to prove they are involved with the reproductive failure.
Reproductive failure occurs when the bred sow or gilt does not conceive or fails to farrow a healthy litter. It may appear as: normal return to oestrus (18-24 days), delayed return to oestrus (<25 days), abortion, pseudo pregnancy, failure to farrow, mummified foetuses, still births, small litter size, abnormal/malformed piglets and decreased neonatal survival.
Some critical factors associated with reproductive performance of female breeding pigs, their lifetime performance and herd productivity in commercial herds include both sow-level and herd-level factors.
High risk sow-level groups for decreasing reproductive performance of female pigs are low or high parity, increased outdoor temperature, decreased lactation feed intake, single inseminations, increased lactation length, prolonged weaning-to-first-mating interval, low birth weight or low preweaning growth rate, a few pigs born alive at parity 1, an increased number of stillborn piglets, foster-in or nurse sow practices and low or high age at first-mating.
Also, returned female pigs are at risk having a recurrence of returning to estrus, and female pigs around farrowing are more at risk of dying. Herd-level risk groups include female pigs being fed in low efficiency breeding herds, late insemination timing, high within-herd variability in pig flow, limited numbers of farrowing spaces and fluctuating age structure.
To maximize the reproductive potential of female pigs, producers are recommended to closely monitor females in these high-risk groups and improve herd management. Additionally, herd management and performance measurements in high-performing herds should be targeted.
Causes of Reproductive Failures in Pig Production
Renowned pig vet Bob Stevenson discusses six major causes of infertility in pigs and how they can be avoided.
1) Poor heat detection
Producers who fail to record the first and second cycle of oestrus activity risk missing any third cycle, when young females are at their most productive.
Mr Stevenson advises farmers to start looking for the first signs of heat when maiden gilts are in the presence of other pigs.
“Observe specifically at 18-24 days thereafter for the second heat and the same interval for the third heat, when she is ready to be served.”
However, he cautions against introducing the boar or inseminating before the female is in correctly identified standing oestrus.
“Don’t mate in the early stages of that third cycle – wait until she stands rigid and doesn’t move forward when weight is borne down on her back, usually in the second day of the cycle.”
For sows, the aim should be to serve four to six days after weaning, when fertility is at its peak.
Sows will occasionally come on heat before three days, but service at this time leads to suboptimal results.
The service period should be regimented, with two or three services 12 hours apart.
2) Mycotoxin contamination in feed and bedding
Mycotoxins caused by moulds and fungi are present in grain and straw bedding.
All pigs are vulnerable, but for breeding animals and youngstock, mycotoxins can damage the placenta and cause abortion and stillbirth.
Adding binders to feed is the best form of defence because these absorb harmful mycotoxins.
Feed bins should be routinely emptied and washed and dried before they are refilled.
Straw should not be used in bedding for breeding pigs and youngstock if it has been baled in damp conditions.
3) Poor management at mating
Fertility can be problematic when service is not supervised.
Wean and mate sows on specific days. “The whole thing needs to be planned, week by week,” advises Mr Stevenson.
“Sows that are within sight, sound and smell – and possibly touch – of a boar are likely to be ready to serve between four and six days after they have weaned their litter.”
The service area should be light to activate the sow’s hormones.
Implantation takes place in the two weeks following mating.
“Attention paid at this time gives the best opportunity for as many embryos as possible to implant. Focus on simple measures like keeping the sow cool and exposed to minimum stressors,” says Mr Stevenson.
He recommends daily recording of all supervised services, with a service graded as good or poor.
“Regular analysis will chart the reproductive success against the target of perhaps 87% farrowing following a service some 116 days previously.”
4) Incorrect body condition score
Females should be at body condition score 3-3.5 at mating to ensure maximum ovulation and good conception.
For traditional pedigree British breeds, it can be difficult to ensure sows are not too fat at condition score 4.5 even 5, while hybrids often need to gain condition for mating. Attention to nutrition in the run-up to mating is therefore important.
“Feeding must be spot on before mating because if the metabolism progresses to a state of negative energy from underfeeding or unbalanced nutrition, the sow may fail to implant adequate numbers or viable young embryos,” says Mr Stevenson.
Record condition scores to monitor the herd’s reproductive success.
5) Too young at first service
Pigs mated before they are five-and-a-half to six months old are unlikely to achieve maximum ovulation.
Avoid premature mating to optimise reproduction.
“Gilts that are mated too young often fail to ever catch up – their performance will be poor in subsequent litters,” says Mr Stevenson.
6) Temperature extremes
High temperatures have a profound effect on fertility by lowering the desire in boars to mate. It can be a real issue for outdoor-breeding herds where temperatures cannot be controlled.
Mr Stevenson says pigs should have access to an ad-lib supply of drinking water. Wallows should be maintained and adequate shade and hut ventilation provided.
For large units, keeping a higher number of gilts or sows than needed can help maintain the required level of farrowings, advises Mr Stevenson.
“This is likely to be an action of increasing importance each season as extremes in weather become the norm.”
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