Volume 12: Livestock Farming
5. Breeding programmes and techniques
Commercial breeding services
Artificial insemination techniques
Artificial insemination services
Regulation of artificial insemination
Artificial insemination centres
Embryo transfer services and their regulation
Embryo transfer and BSE
Meat and Livestock Commission breeding services
Milk Marketing Board breeding services

Artificial insemination techniques

5.20 In a normal mating, a bull produces up to 500 times more semen than is required to enable a cow to conceive. AI involves the collection, dilution, and storage of semen, and then the insemination of many cows from one ejaculate. ¹

5.21 Once collected, semen is divided into fractions and injected into the cervix or uterus of a cow in oestrus, or, in commercial practice, diluted 20 times or more and distributed into plastic tubes, or 'straws', to be used when necessary. ²

5.22 Semen can now be stored for years using modern freezing techniques. Glycerol is added to the sperm diluent, which allows the sperm to withstand freezing without losing their fertility when thawed. Diluted semen is now commonly stored and frozen using liquid nitrogen. ³

Artificial insemination services

5.23 Breeding programmes throughout the 1980s relied on progeny-testing ofwell-bred young bulls to enable the best to be returned to stud as mature sires for widespread AI use. ⁴ Current breeding programmes rely on similar testing systems.

5.24 First, the government State Veterinary Service (SVS) approves young bulls for a strictly limited number of progeny-test inseminations. About 1,000 straws of semen are produced from the bulls soon after entry into an AI centre. About 750 from this collection are used for the progeny-testing. After the semen required for these tests has been collected and frozen, the bull is 'laid off' for five to six years until its breeding worth has been established by lactation records in about 40 to50 daughters. ⁵

5.25 Only the very best of the progeny-tested young bulls are returned to stud for extended use. Those bulls then complete 'many tens of thousands of inseminations'. ⁶ However, if a bull is thought to have exceptional genetic merit then several thousand straws may be collected before the progeny-test is complete in case the bull dies before completion. ⁷ As part of progeny-testing the bulls are backcrossed with daughters to test for genetic mutations that lead to disease. They are not tested for mutations of the prion protein gene ⁸ or other genetic mutations.

5.26 In January 1990 MAFF introduced a policy to eradicate BSE-infected bulls from the approved bull scheme. If BSE was confirmed in a bull, its approval was suspended, and semen already collected from that bull could not be used. If BSE was confirmed in a bull's dam or surrogate dam, it would be left to the owner's and AI centre's judgement as to whether to continue using semen from that bull. The scheme is discussed in further detail in vol. 5: Animal Health, 1989-96.

Regulation of artificial insemination

5.27 The Artificial Insemination of Cattle (Animal Health) (England and Wales) Regulations 1985 govern the animal health aspects of AI. These Regulations:

... prohibit the collection of semen for processing unless from an approved bull. They also prohibit the evaluation, processing, quarantine, storage and supply of semen for use in AI except under the authority of licences granted by a Minister, and the premises at which the above functions are carried out must be licensed for the purpose. Farmers wishing to store bull semen for use on their farm must also obtain a licence. ⁹

5.28 Veterinary officers inspect and report on the suitability of premises before a licence is issued under the Regulations, and periodic inspections are carried out to ensure continued compliance. ¹⁰

5.29 Before approval for AI use, bulls are required to meet specific veterinary standards and are examined for this purpose by an SVS veterinary officer. Bulls at AI centres are also subject to periodic examinations and tests by the SVS. ¹¹ They are tested for a variety of ailments including tuberculosis, brucellosis, enzootic bovine leukosis, trichomoniasis, and campylobacteriosis. ¹²

Artificial insemination centres

5.30 Up until 1994 the Milk Marketing Boards and the Department of Agriculture for Northern Ireland (DANI) operated about 120 AI centres around the UK. ¹³The centres, particularly in England and Wales, were run in conjunction with breeding units for bull rearing, progeny-testing units, and semen quarantine, storage and distribution units. In addition, AI services were provided by a small network of independent AI centres in the UK, for example, Associated AI Centres in England and Wales.

5.31 The AI centres stored semen, and provided skilled technicians to visit the farm to inseminate the farmer's cows. A farmer needed to become a member of the AI centre to receive services. Membership was open to beef breeders as well asmilk producers. ¹⁴

5.32 Abolition of the Milk Marketing Schemes in 1994 and the subsequent disbanding of the Boards led to independence for their breeding and production services. Genus Limited became responsible for the Board's services in England and Wales, while Scottish Livestock Services took over from the Scottish Milk Marketing Board's Livestock Division. ¹⁵

5.33 Only inseminators from AI centres are licensed to perform inseminations on a commercial basis, but farmers or staff can attend an approved training course and be licensed to carry out inseminations on their own farm. The local AI centre makes deliveries of semen, and provides liquid nitrogen top-ups for storage. In March 1986 approximately 2,400 farms in England and Wales held storage licences, about700 farms in Scotland, and 795 in Northern Ireland. ¹⁶ By 1996 over 4,000 farmsin England and Wales had licences, around 800 in Scotland, and 1,650 inNorthern Ireland. ¹⁷

Embryo transfer services and their regulation

5.34 Embryo transfer began in the UK on a significant scale in 1972. By the mid- to late 1980s it was estimated that there were 10,000 embryo transfers per year in Great Britain. ¹⁸ There was no regulation of embryo transfer in the UK until 1993, when the Bovine Embryo Collection and Transfer Regulations were made to implement the requirements of EC Directive 89/556/EEC. ¹⁹ The Regulations required the official approval of teams collecting bovine embryos and regulated the transfer of embryos into recipients; they also included provisions to protect the welfare of donor and recipient animals.

5.35 The 1993 Regulations were replaced in October 1995, when the Bovine Embryo (Collection, Production and Transfer) Regulations 1995 came into force. The 1995 Regulations were similar to the 1993 Regulations but extended their scope in several respects, for example, to include all embryos. ²⁰ By 1996, there were 25 teams approved in Great Britain for both the collection and transfer of bovine embryos, all but one of which were approved for intra-Community trade as well. ²¹

Embryo transfer and BSE

5.36 In 1992 the EU implemented new controls in response to the BSE problem in the UK. Commission Decision 92/290/EEC required that any donor females used in the embryo trade from the UK had to be BSE-free, born after 18 July 1988, and the offspring of a cow unaffected by BSE. ²²

Meat and Livestock Commission breeding services

5.37 The main objective of MLC beef breeding services throughout the 1980s was the 'progressive improvement in the genetic potential of commercial cattle to produce high quality beef economically'. The core service was the Pedigree Recording Scheme, used by the majority of breeders rearing bulls for service. ²³The MLC also operated 'performance testing stations' for beef bulls up until 1986, where bulls owned by various farmers could be sent at the age of about six months. After 1986 testing was carried out on farm under MLC beef specialist supervision. ²⁴

5.38 The MLC continued to play an active role in the development of breeding technology through the 1990s via its research and development programmes.A priority was the 'development and implementation of breeding programmes based upon technologies such as Best Linear Unbiased Prediction (BLUP) and Marker Assisted Selection (MAS) cross-linked to bovine gene maps.' ²⁵ The MLC saw itself as an important facilitator of improved breeding, using its programme of research to deliver new techniques to the industry. ²⁶

Milk Marketing Board breeding services

5.39 In addition to providing AI services, Milk Marketing Boards in Great Britain and DANI provided breeding programmes for farmers, with the main object of herd improvement. The basis of the programmes was effective progeny-testing. These testing programmes were also used to assess the breeding qualities of beef bulls, mainly for use in dairy herds to produce crossbreed calves for rearing asbeef animals. ²⁷