The Evolution of Swine Artificial Insemination

by Phil Burke


The use of artificial insemination (AI) in livestock has been utilized for nearly a thousand years. Records suggest that Arab Chieftains experimented with AI on horses as early as 1322.

The birth of modern swine AI is thought to have begun in England in the mid-1950s by Dr. Christopher Polge. Dr. Polge had worked on poultry and bovine semen preservation (mainly freezing) before moving onto the preservation of boar semen.

The use of AI in Europe has been widespread since the 1970s, utilizing small localized AI studs that serviced an area and often provided insemination technicians to visit each farm to inseminate the sows in heat (similar to beef/dairy insemination practice).

Between 1993-2000, the growth of AI transitioned from on-farm collection to large off-site studs that rapidly changed the industry.

AI was used several times in the US on commercial sow farms before it became standard practice in the early 1990s.

Between 1993-2000, the growth of AI transitioned from on-farm collection to large off-site studs that rapidly changed the industry. The expansion and size of the new sow farms built, adapted and adopted the use of conventional AI. Farms grew from several hundred sows to several thousand sows on a single site and the need/search for specialized heat check and insemination technicians began.

Concentration fell from 5 billion cells per dose to 3.0 billion cells per dose. Volume was reduced from 120ml doses down to a 70ml dose. Semen production advanced from a manual filling process to the use of high-output automated packaging machines.


By the millennium, AI was used on more than 99% of all sows inseminated, over 35,000 boars were housed in 200+ studs in the US. The days of having 400,000 natural service boars on farm were over.

The size of the boar studs continued to grow up to 800 boars on a single site. Eventually, a model of 400-500 boars on a single site was determined to be the best size for logistics and biosecurity management.

Long term semen extenders will allow for semen to be delivered to the farms less frequently, thus reducing the biosecurity delivery risk.

The analysis of boar semen quality was now becoming an increasing focus. The introduction of Computer Aided Semen Assessment/Analysis (CASA) became widespread on studs over 250 boars, as the number of boars collected per day and subsequently the number of doses produced on peak production days escalated. The need for qualified and trained laboratory technicians became apparent, as these new large studs impacted a large volume of sows every week.

By 2010, the initial use of Post-Cervical AI (PCAI) began in the USA. This type of technology had been used on a smaller scale in Europe, particularly Spain, for some time. This changed the placement of the semen from the cervix using a conventional catheter to the uterine body. With practice, success and time, the concentration per dose was reduced from 3.0 billion cells down to 1.3 billion cells. Some systems use a conventional 70ml dose volume while others have adopted a 35ml dose volume. Storage and delivery can be from a tube, bag or a bulk bag delivery method. In 2020, PCAI will exceed 50% utilization for the first time in the USA.

Experimentation and the commercialization of fixed-time AI has been tried and tested. Acceptance and results were mixed. This technology will be improved and will be implemented successfully again in the future.

Frozen semen has also developed greatly over the years and is a vital tool for semen exportation to countries that require extensive testing prior to entry. The days of producing 8 doses per ejaculate, 70% farrowing rates and a piglet less born alive than ‘fresh’ AI have long gone. With professional freezing, good management of the liquid nitrogen tanks and trained staff on the receiving farms, results can be comparable with conventional ‘fresh’ AI.


Long term semen extenders will allow for semen to be delivered to the farms less frequently, thus reducing the biosecurity delivery risk. In recent years, customers have demanded semen to be delivered up to 3 times per week and the mindset that ‘fresh-is-best’ has become the standard. It is expected that with the development of new extenders; utilizing better quality water in the dose; the forced reduction of antibiotics (both levels of inclusion and antibiotic types) and storage/management at lower temperatures (5°C) will again lead to a move to once per week delivery.

Beyond PCAI – Work is on-going to test semen doses below 1 billion cells and utilizing a dose volume of 10ml or less. The use of new technologies/equipment beyond the range of current CASA capabilities will be needed, in addition to new research funding.

It has been thought that sexed swine semen would be the logical next step, following on from the use of sexed semen in cattle. Significant research time and dollars have been invested on this delivery method. While sexed semen will clearly have a need, it is unlikely that this will become standard practice on-farm.

AI has been called many things over the years, including Gene Transfer. With the advent of African Swine Fever and the likelihood that the dissemination of swine genetics will see new levels of control and regulations, the movement of live animals and fresh ‘liquid’ semen may be coming to an (a temporary) end. The use of embryo transfer and cloning will again be investigated for future usage.

Phil Burke graduated from Harper Adams University in Shropshire, England in 1989. He joined the PIC management trainee program with PIC UK. In 1993, he transferred to PIC USA to implement artificial insemination onto US pig farms. He joined Minitube of America in 2005 and ran Technical Service and Business Development. Today, Phil is National Accounts Manager for Anpario Inc.