What stops me achieving an 85% farrowing rate?

Any sow or gilt which has a questionable reproductive history should be mated by the most experienced breeder on the farm

Season	Summer infertility occurs on most farms to some degree. The farrowing rate drop can drop by 5-15% depending on the farm. Analysis of records will provide a history of previous seasonal effects. A summer with variable high temperatures appears to have greatest reproductive problems. The graph below shows results for the northern and southern hemispheres (USA and Australia).
Month of breeding
Repeats	The number of repeats has a significant negative effect on farrowing rate. As the sow or gilt repeats her next farrowing rate drops precipitously. All gilts which repeat should be mated by a boar at least once.		Repeat	Farrowing rate
			0	82%
			1	70%
			2	60%
			3	40%
			4	25%
Discharges	Sow/gilt repeats at 14-21 days post-mating. The primary cause is mating late and the introduction of bacteria into a defenceless uterus.
Gilts	Gilts in general only have a 75% farrowing rate.
Heat number	As the gilt matures the farrowing rate and litter size increases.
Feeding post mating	Feeding too much energy post-mating will reduce the farrowing rate. Limit the gilt to 2kg a day 14MJ diet for 14 days post-mating.
Poor acclimatisation	If the gilt is not acclimatized properly she will be more susceptible to the effects of pathogens – particularly viruses. PRRSv, SIV and erysipelas would be examples.
Return gilt	Any gilt that has a return should be mated with the most experienced breeder and ideally by a boar. It is essential to get the gilt pregnant to minimize parity loss.
Lactation length	As the lactation length increases to 17 days the subsequent farrowing rate increases. Increasing lactation length may increase the number of sows which demonstrate an oestrus during lactation.
Wean to service interval	It is essential to mate during the period 4-6 days post-weaning. If mating 2 days or between 7 and 14 days post-weaning the farrowing rate falls precipitously. However, it is essential that the sow is in oestrus when mated.
Sow age	The gilt has a lower farrowing rate of sows at 75%. The farrowing rate decreases again after parity 6, falling below 80%. Note the parity structure of the herd. Limit parity 7+ to less than 8%.
Semen flow	Monitor boar fertility – including AI boars. Cull all boars with a farrowing rate < 75%.
Semen age	Note semen age – ideally use before day 3 post-collection
Semen storage	AI semen must be stored between 15 and 20°C – ideally around 17°C. Monitor the temperature fluctuations. Note if too many semen doses are taken to the mating barn.
Semen handling	Ensure the AI mating is carried out cleanly. Only mate sows and gilts that are in heat. Do not leave the catheter in more than 10 minutes after mating.
Boar housing	Boars will go sub-infertile if the temperature is above 30°C for any length of time – 2 days. Monitor the temperature of the boar’s accommodation. Note that any infertility can last 6 weeks or more.
Abortions	The majority of abortions are difficult to pin point or assign a cause. However, pathogens may be controlled by gilt introduction and acclimatization programmes. Environmental causes should be avoided – draughts and variable temperatures. Avoid feed related causes - mycotoxins
Movement	Avoid moving the sow/gilt from day 3 to day 24 post-mating.
Mixing	Avoid mixing the sow/gilt from day 3 to day 24 of pregnancy and always mix in the evening and start the feed cycle. Use scents to minimize fighting.
Culls	It is essential to properly ascribe the cause of the failure to farrow. Too many sows are “culled” on the records and the real cause is not defined. This only causes chaos.
Non- reproductive	It is imperative to minimize the sows culled for non-reproductive reasons. This must be done before the final pig flow decisions have been made. Review all sows in the mating pool for conformation issues – body condition, leg structure and mammary gland observations. Sows which are unsuitable for mating should have been determined 6 weeks prior to the previous farrowing.
Reproductive	Only cull pregnant animals as part of the pig flow model with culling at pregnancy checking. These culled pregnant sows should be removed from the farrowing rate calculation. They were mated to improve their feed conversion efficiency, improve their sale value and provide insurance against a potentially empty farrowing crate.
Deaths	It is vital to eliminate cystitis and pyelonephritis deaths. These are all associated with poor water supplies in gestation or the previous lactation.
People
Breeding routines	Ensure that sows in heat which are skipped until the next day actually get pregnant. This is classically day 4 post-weaning animals. Note there is little difference in the farrowing rate between 4 and 5 days post-weaning.
Pig Flow	Ensure breeding targets are set and met.
Multiple matings	Review mating programmes ensuring that sows and gilts are mated twice. Three times mating often demonstrate a higher farrowing rate, but this may be only a feature of the wean to service intervals. Sows with short wean to service intervals stand longer and are more fertile. Two matings should be sufficient to achieve pregnancy.
Oestrus behaviour	Well trained stockpeople will recognized the signs of oestrus. Gilts may demonstrate good signs of oestrus but it may be short. In sows the signs of oestrus may be more subtle. In large herds separating heat checking from mating has improved the farrowing rate.
People	Not everyone is suited for heat detection and mating protocols.
	Examine the use of breeding aids such as belts and weights.
Post-mating behaviour	Ensure that the sow or gilt is provided with a gentle environment in the immediate 5-10 minutes post-mating. This allows the semen to be transported within the uterus to the oviducts.
Pregnancy checking	It is essential to recognize the none pregnant animal as soon as possible. The most effective pregnancy checking machine is the boar. Detecting an open sow in week 16 of “gestation” is not adequate

The difference between conception rate and farrowing rate should be less than 3%

The following is an embedded excel spreadsheet which can be utilized to demonstrate the discussion above.