Management of your semen thermal store matters

LCD indicating the temperature inside the thermal store – correct.

Managing the semen thermal store is the most important part of farm management. But is this not often just a little box, where you put newly delivered semen, batch after batch, and just assume it will work? Do you actually manage this little box? How often do you read the temperature reading? Do you just trust the LCD reading outside the box (assuming that this is even working)? What are your management standard operating procedures? Is that annoying reproductive concern really a problem with your artificial insemination (AI) box?

Figure 1: Transporting semen to your farm is more than just delivery – it can be subjected to stresses that reduce semen quality.
The semen delivered to your farm has to arrive in excellent condition. AI studs put enormous effort into producing quality semen with a life span of 5-10 days (depending on diluents used). But the delivery system can fail. In this case, PIC (which produces excellent semen) delivery became unstuck by the postal service breaking apart the fragile box!
The box had been used as a football during the World cup (seriously!).

Since the 1990s, most of the world’s pig breeding stock are mated using fresh diluted semen. The freshly collected semen is rapidly diluted in an osmotically correct diluent. A boar ejaculates about 200mL of semen with a concentration of about 100,000,0000,000,000 (10 x 1010) spermatozoa (range 2-12 x1010 spermatozoa). This is then diluted by the AI stud, to produce doses of 2,000,000,000 (2 x 109) spermatozoa in 40-80mL of diluent. Thus about 50 doses of semen can be made for traditional intra-cervical insemination. But what is fresh? Normally the diluted semen will have a life-span of 5-10 days when stored at the correct temperature.

Semen movement to your farm

Hygiene and cleanliness of your semen thermal store

Semen is the lifeblood of your farm, thus treat its storage with respect and keep the semen store clean and well-maintained.

Temperature management of your semen thermal store

Boar semen is generally used fresh within five days of collection. Pig semen is generally not frozen, because pig cell membranes do not survive defrosting well. In addition, pig genetics progresses too fast for frozen semen use, outside the pathogen advantages. So most frozen semen move between nucleus farms.

Fresh boar semen should be kept at 17°C with an acceptable range of 15-19°C. Do you properly monitor your semen thermal store? Does the semen arrive to you having a good ‘cold chain program’?

Semen thermal stores should regularly be checked using a temperature electronic monitoring device. Talk to your veterinarian about this service.

Figure 2: Do not take short cuts when storing semen on-farm.

Good and bad semen thermal store problems revealed by temperature monitoring

In my standards, I set the recorder to record every 15 minutes and record for at least a week over the breeding batch.

In each of these four examples (Figure 4), semen store issues were the specific cause of subfertility records and batch failures in three cases.

Figure 3: Proper storage of semen on-farm, especially optimal temperature, is essential to protect semen quality and maximize shelf life.

Figure 5 shows the importance of thermal monitoring. Clearly, semen thermal box 2 was not working and only following the external temperature. The issue was poor wiring in the plug. Note the temperature was correct mid-afternoon when the box was checked! Even the semen in thermal box 1 needed review and was placed in an air conditioned room to even out the daily temperature variations. 

Figure 4: Temperature recordings for semen storage – ideal (top left) and storage problems.

Management of the semen within the thermal store

Semen must be kept in contact with fresh diluent. The purpose of the diluent is to buffer (protect) the semen from respiratory by-products – mainly lactic acid. It does not feed the semen. Therefore, it is general advice to turn and rotate the diluted semen package twice a day. This is more important when using tubes or bottles versus flat pack semen storage devices as the semen will concentrate as a pellet with the diluent on top.

If the semen thermal store is over-stocked this will reduce the air flow and effectiveness of the semen thermal store.

Figure 5: A classic example where 24 hour temperature monitoring was vital.  Fixing the problem raised the farrowing rate from 65 to 85% and increased total born.

Which boar is which?

When dealing the multiple boars breeds or lines ask the AI store to color the semen diluent so that identification is easy.

Figure 6: Correct storage of semen, including removing from secondary packaging and placing horizontally will improve air circulation to stabilize the temperature.

When not to use the semen?

If there are any concerns about the semen quantity or quality, do not use! Insist on replacement.

Remember teaser boars also produce semen – there is nothing wrong with natural mating.

Table 1: Impact of AI semen storage on the farm.

Cost of a mistake in the semen thermal store

If there is a fault in your semen thermal store, the sows will not get pregnant and will instead return to estrus. This could be between 18-24 days post-service – a regular return or between 25-35 days post-service with embryonic death. If the store is acting variably, the impact can also be variable.

Figure 7: Colored semen makes identification the boar simple.

When you breed with defective semen it is likely to take four weeks before you notice – as in the sows have to return.

If we assume the semen thermal store stops working and the semen dies, the cost of this error can be calculated as a loss of nearly 8% of the annual production. And if the cost of production is 1 unit/kg, there would be about 18,500 units of production loss.

Thus, in Australia, the failure of the AI store, a cost of production at AUD 3.10 results in losses of AUD 57,000 before the issue is detected! What other single piece of equipment can result in such losses?

Table 2: The impact of one boar on the pig farm/industry.

How boars can impact the variability of finishing pigs in production

Pig farming techniques should always aim to reduce the variability of the system in pork production, an essential food supply for this planet, and to reduce production cost. Table 2 shows the impact of one boar, assuming 50 doses of diluted semen is made for intra-cervical insemination.

Figure 8: Fungal contamination of semen is harmful for sperm viability and represents an infection risk for inseminated sows.

It is easy to see why in the late 1990s AI finally exploded in the world of pigs and with the advent of different mating strategies, one boar can make nearly a 300 times improvement from that possible with natural mating, thus significantly reducing the variation in the system. When the boar selection focuses on meat quality and food conversion ratio, these can make massive improvements in the cost of production.

The semen thermal store is a vital piece of farm equipment and its management matters.

Dr John Carr ([email protected]), is a well-known consultant in Asia, North America, Europe and Africa. He specialises in maintaining the health of pigs through promoting excellence in stockmanship and production practices. A frequent and popular conference speaker, he is widely published, including editing the comprehensive reference guide, Managing pig health – a reference for farms. ( He is also the author of the veterinary textbook ‘Pig Health’. In Australia he works with Apiam Animal Health.

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Based and working in the region.