Animal Genetic Improvement

Environmental Issues Farmers engaged in livestock production for the market increasingly change local breeds for exotic breeds or crossbreeds. Genotypes from local breeds with small numbers of animals are at particular risk of disappearing. Pressures for change include: Change in perceived value of species and breeds. More selection on production characteristics. Requirement for more efficient and cost effective farm management resulting in a range of incentives to keep exotic breeds (including greater production levels). Local breeds exchanged for exotic and cross breeds. | Environmental Issues Objectives Techniques Costs Targeted Livestock System Context of Application Impact References Further Reading

Objectives

To have an animal which is more productive, more efficient in terms of resource utilisation (lower input/production ratio). However, this increased productivity is normally associated with a decreased succeptability to disease, a reduced tolerance of environmental extremes (cold, heat, lack of water), and an increased need for external inputs and specialised animal housing. Where the required capital outlay and levels of cash flow are insufficient, investment in "improved" livestock breeds may prove to be uneconomic and may also result in reduced productivity. |

Techniques

Genetic improvement is done through two techniques, selection and cross-breeding.

Selection in a population makes it possible to increase the average value of one or several characteristics, chosen beforehand to improve the genetic potential of animals of this population. Cross-breeding makes it possible to combine the advantages of several breeds. In fact, the limits of selection and reproduction in pedigree breeds (increased consanguinity, lack of effectiveness of selecting characteristics with poor inheritance ability, etc.) have led to researching the possibility of mating breeders of different breeds. |

For faster advance of genetic progress, artificial reproduction techniques have replaced natural mating: artificial insemination and more recently embryo transfer.

- Artificial insemination is an operation which consists of depositing with an appropriate instrument the semen of a breeding bull into the appropriate part of the genital organs of a female in her fertile period with a view to fertilisation; the semen is collected, examined, diluted, conditioned and usually conserved beforehand.
- Embryo transfer is a technique of artificial reproduction which consists of removing the embryo(s) from the genital organs of a female called a donor after fertilisation in order to transplant it (them) in the genital organs of one or several females called recipients, where the embryo(s) will develop until birth.

Costs

These depend on the method of genetic improvement used. In West Africa, costs of the Gobra selection methods are estimated at around US$ 2.43 per cow per annum.

Targeted Livestock Systems

Techniques for genetic improvement are used widely in all animal production systems throughout the world.

Grazing System

LGA | LGS1 | LGS2 | LGS3 | LGH1 | LGH2 | LGH3 | LGT1 | LGT2 | LGT3
Y | Y | Y | Y | Y | Y | Y | Y | Y | Y

Mixed System

MCG | MCR | MCC | MFF | MEF
Y | Y | Y | Y | Y

Industrial System

IFP | IPL | IPG | IRM | IDU | ISL | ITN | IMP
Y | Y | Y | Y | Y | Y | Y | Y

Impact

- Positive environmental impact

- Reduction of animal pressure (since the animals are more productive, the production system can be intensified and thus one can have fewer animals to maintain for the same level of production).

- Negative environmental impact

- Reduction of animal biodiversity.
- Introduction of new pathology.
- Increase in grain field areas.

- Impact on livestock productivity (milk, reproduction, meat, health, etc.)

- Meat: increase by 1 to 2 % per annum.
- Milk: increase of 0,5 to 1 % per annum (these increases are cumulative).
- Meat quality: this may improve, but the quality of meat from older varieties of livestock is often considered to be better (and may therefore obtain higher prices, e.g. rare breeds).
- Reproduction: increase obtained by cross-breeding, (but not cumulative).
- Health: animal more productive but often more fragile (requiring more expensive veterinary and other external inputs).
- Feed: animals may require higher quality fodder and external feed inputs.

Context of Application

Everywhere in the world, genetic improvement has an ancient history. The action of man, which has contributed to the creation of breeds which are sometimes very homogenous, has been added to natural selection leading to isolation of certain breeds.

- Favourable factors:

- Increased requirement for animal products.
- Shared concern to reduce animal numbers.
- Wish for improved management of breed potential.
- Improvement in performance of artificial reproduction techniques.

- Unfavourable factors:

- Difficulty in controlling genetic progress in extensive livestock systems.
- Difficulty of certain improved breeds to live in certain environments.

References

IEMVT/CIRAD, 1989. Elevage et génétique, Fiche n° 9, December 1989. Ministère de la coopération et du développement IEMVT/CIRAD pp.12.

Chupin D., Wagner H. , Wilson T., 1993. L'amélioration génétique des bovins en Afrique de l'Ouest. Rome et Banjul (GMB), FAO, 296 p. (Etudes production et santé animale n° 110)

Le Gal O., Planchenault D., 1993. Utilisation de races caprines exotiques dans les zones chaudes. Contraintes et intérêts. UCARDEC/CTA/CIRAD, pp. 261.

Meyer C., Denis J.-P., ed., 1999. Elevage de la vache laitière en zone tropicale. Montpellier, Cirad. Cirad-emvt, pp. 316 (Collection techniques).

Payne W.J.A., Hodges John, 1997. Tropical cattle. Origin, breeds and breeding policies. Blackwell Science, 328 p.

Further Reading

Diversity in Ecological and Socio-economic Settings

Loss of Agricultural Bio-diversity

Loss of Agricultural Bio-diversity: Pressure-State-Response Indicators

OECD. 1997. Issues in the sharing of benefits arising out of the utilisation of genetic resources. Click here to view the document in Acrobat format (123KB)

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