As a livestock farmer, improvements in your animals will positively impact on your animal production business.
But most farmers don’t know about it.
This post will explain what you need to know about animal improvement in agriculture.
Aims of animal improvement
Animal protein is the best souree of protein
for hunmans because it contains most of the
essential amino acids in the right proportion.
The consumption of animal proteins in the
developing countries, in the form of meat,
egys milk and milk products such as cheese,
is below the average required for good health.
This is not because the people do not enjoy
such food, but because animal proteins are
still too expensive for the majority.
Also, most of the native breeds of animals in developing countries are poor yielders. Thus there is widespread malnutrition.
To change this unfortunate situation,
animals must be improved to increase yields.
This can be done by evolving breeds which are more productive because they are physiologically more efficient.
This means transferring an inherited superiority from one domesticated animal to others of the same species.
As well as increasing yields, it is also
important to improve the quality of the products. Fortunately all agriculturally important traits are heritable and they can be transferred from animals to their offspring by
Such qualities include the butter fat percentage in milk, quantity and quality of fats and muscles in meat animals, yolk size and shell hardness of eggs, wool quality in sheep, and hardiness in work animals such as horses and bullocks.
Animals can be bred for resistance to disease. Certain insects and diseases for instance trypanosomiasis, are prevalent in the forest and derived savanna zones of Nigeria.
Thus certain breeds of animals cannot be kept in these zones, although pasture exists, unless disease-resistant stock is introduced.
Methods of animal improvement
There are three major ways of improving the
heritable qualities of animals. These are by
introduction, selection, and breeding.
Many animals which are not natives of a place but are known to have certain desirable
characters have been brought into new lands
from their places of origin.
Such animals will be able to survive if the environmental conditions are favourable to them.
Introduction can be by physical importation either of the animals themselves or of their spermatozoa.
Animals so brought are first quarantined to
make sure they are disease-free.
Many dairy cattle such as Friesian, Holstein, or Jersey, and beef cattle such as Aberdeen Angus, Shorthorns, and Red Devon, have been brought from Europe and America to experimental stations and government farms where some are reared in confinement and some in open fields.
The aim is to introduce good milk producers to provide fresh milk and other dairy products for people in the thickly populated areas; to test the economic desirability of such a venture; and to use these animals to upgrade the less productive local breeds.
N’Dama, a good beef breed which is resistant to trypanosomiasis, was introduced to Nigeria from Guinea.
In the case of pigs and poultry, imported breeds have almost replaced the local breeds in commercial production.
This is the selective breeding of animals with
certain desirable characteristics.
Selection can be natural or artificial. The former means that animals having certain characteristics which enable them to thrive in their particular habitat become dominant to those without.
In artificial selection, man picks for breeding the animals in which desirable characteristics are more developed.
The ability to do this is a great asset to the breeder. This art of selection has been practised for a long time, but it is now being greatly extended by fundamental training in the biological sciences.
Some of the agriculturally important characteristics used as a basis for selection in livestock are fertility, infant mortality,
growth rate, size, milk yield and quality, fat
and meat quality, rate of egg laying, resistance to diseases and ability to work.
Selection does not create variations, but
only acts on variations already present in the
organisms. It is therefore only effective when
based on differences that are heritable.
The inherited characteristics are transmitted
through the genes which are located in the
chromosomes present in the nucleus of every cell.
Genes are responsible for the development of certain characteristics in individuals
living in certain environments. They are
transmitted from parent to offspring through
the male and female gametes.
Since all farm animals are unisexual, care
must be taken to maintain the selected
characters by mating male and female
animals known to have such specific characters.
Selection in such animals can produce improved varieties with gene combinations different from and superior to that which had been present in the original population.
Heritable qualities are transferred from the
parents of animals to their offspring during
breeding. There are three major types of
breeding: inbreeding, outbreeding, and cross-
This is where offspring (progeny) are produced by the mating of closely related pairs, for instance brother with sister
parent with offspring.
lt is used to eliminate some of the detrimental genes and to retain some of the desirable ones.
Inbreeding either makes the genes in a particular organism all dominant or all recessive.
When the recessive characters come out, they may have deleterious effects; hence it is generally said that nature abhors perpetual self-fertilization or inbreeding.
Pure bred or pure lines can usually be achieved after ten or twelve generations of continuous inbreeding.
When dominant characteristics of a pure bred animal are of agricultural importance, then the line is kept pure by continuous inbreeding.
Although it takes a long time and is very
expensive to achieve pure lines, it is worth the effort in the long term. Pure line animals
retain their characteristic permanently.
This involves mating of individuals which are not closely related but belong to the same breed, for example second cousin with second cousin.
It is used to introduce some ‘new blood’ into the herd.
This is the mating of animals which belong to different breeds, for instance NDama with Muturu in cattle or Landrace with Large White in pigs, in order to introduce new blood into a herd.
It results in hybrid varieties which show hybrid vigour (heterosis). It brings about a faster growth rate and masks the appearance of undesirable characters.
It increases variability of the species, so offspring are generally more adaptable to changing environmental conditions.
The most important cross-breeding is that of two genetically different pure-bred lines.
The first generation can be used only
production and not for reproduction (breeding).
The more highly inbred the parents are, the
better the heterosis, viability, and fertility of
Upgrading of local breeds of animals whose
genetic constitution is not known (i.e. scrub)
can be effected by crossing with pure-bred
imported (i.e. exotic breed) animals of the
same species. This type of crossing can be
facilitated by artificial insemination.
Artificial insemination is the introduction of
spermatozoa into the female genital system by human devices and not through the process of coition between the male and female animals.
For artificial insemination to succeed, the
oestrous cycle and especially the relationship
between heat period and ovulation must be
This is because, in most livestock except poultry, sperm are only viable for a few hours after insemination in the female genital duct.
The process requires a lot of skill and should be carried out by well trained personnel.
Artificial insemination has genetic as well
as economic advantages. It is cheaper because sperms can be transported from one part of the world to another very easily at low cost.
Few male animals of proven qualities need to
be maintained on the farm. Disease spread is
reduced because of lack of physical contact
with many males during mating.
Semen stored in liquid nitrogen at 196 °C
can be maintained indefinitely and used
whenever the need arises.
There are large numbers of sperms in a small quantity of semen so many offspring can be produced by one male animal within a year.
This means that a herd can be improved very quickly.
Artificial insemination quickly upgrades
poor local breeds since sperms from the same animal can be stored for a long time and used to cross many generations of the scrub.
However, inbreeding effects associated with the appearance of undesirable traits may set
Some other disadvantages include: the
scarcity of experts to perform the operation
and know the appropriate quantity and
quality of semen to use; restraining of the animal; storing the semen; discomfort suffered by the animal when tying and dipping hand and instrument into the genital duct.
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