Animal improvement is defined as a process where new varieties of animals with improved qualities than their parents are produced through the application of scientific breeding techniques.
Aims of Animal Improvement
(i) To produce animals with high productive potentials.
(ii) To produce animals that can adapt to environmental changes.
(iii) To produce animals which are resistant to pathogenic diseases and pest infections.
(iv) To produce hybrid varieties with high prolific rate, vigour and improved quality.
Methods of Animal Improvement
The methods of animal improvement include:
(iv) Breeding system.
This is the phenomenon in which new species of animals are imported from their countries of origin to a new’ country to improve the natural stock. These newly introduced animals are known as exotic animals while the existing native stock of animals are called indigenous or local animals. The animals to be introduced into a country must be screened and certified to be disease -free. This is to avert the outbreak of disease due to unchecked carriers of pathogenic agents in the imported exotic species of animals.
Advantages of introduction
(i) It facilitates the production of exotic animals adaptable to the climatic condition of the new environment.
(ii) It helps to improve the yields of animals.
(iii) It helps to produce animals with increased productivity and thereby improve the standard of living in a country.
(iv) It helps to upgrade the quality of the local stock.
(i) Introduced animals may be prone to local diseases and this may tend to reduce their vigour and performance.
(ii) Introduced animals may not easily adapt to the harsh climatic conditions of the new environment.
(iii) It is very expensive to practise.
(iv) Introduced animals may be carriers of certain diseases that remain undetected during screening exercise at the point of entry by veterinary personnel.
(v) Introduced animals may not be able to withstand the environmental stress and low nutritional supply compared with their ancestral background at the home environment.
This is the process whereby newly imported species of exotic animals into a country are confined for a period and made to undergo certain tests to determine the health status of the animals if they are disease-free or carriers. In Nigeria, the quarantine test is done at the International Institute of Tropical Agriculture. (I.I.T.A).
Quarantine involves the subjection of animals to screening and observation within paddocks to yield the desired results for certification. This implies a state of disease-free or carrier of the animal from the animal records kept within the duration.
The quarantine practice helps to detect the period of incubation of pathogens in animals.
Advantages of Quarantine
(i) It is an. accurate test for pathogens in animals.
(ii) It gives a valuable report of animal health.
(iii) It promotes the safety of other animals in a stock.
(iv) The process requires close observation on animals under hygienic conditions.
Disadvantages of Quarantine
(i) It is a test that spans through a long period.
(ii) It is laborious.
(iii) It is expensive.
(iv) It requires highly skilled veterinary personnel.
(v) Environmental stress may reduce the vigour of the exotic animals during the process.
Selection involves a great accuracy of choosing animals with certain desired external qualities that are visible at a particular time. There are different systems of selection and these include:
(i) Mass selection: This is the process in which a large number of animals with desired external qualities such as body conformation, milk yields, meat quality, feed efficiency, reproduction rate, and disease resistance are chosen out of the lot.
(ii) Line selection: This is a system in which individual animals with desired traits are selected and used for reproduction in a stock. The major advantage is that it is an accurate assessment of animal morphological features while its disadvantage is that it is laborious and cumbersome.
(iii) Pedigree selection: This is the system of selection where the performance of offspring animals are compared, based on their parents’ distinct qualities or performance.
Disadvantages of Selection
(i) It is cumbersome.
(ii) It can only be done by highly skilled specialists in animal science to yield valuable results.
(iii) Certain selected animals may vary in their individual characteristics, thereby distort future morphological conformity of offspring.
(iv) Certain traits inherent in animals may be lost during selection.
(v) Selection is not genetically based, but dependent on morphological or physical observation.
Breeding is a method of animal improvement in which new species with improved vigour and qualities are produced through the transfer of inheritable qualities from the fused gametes of male and female of animals in sexual reproduction process. The different systems of breeding include: inbreeding, out breeding, crossbreeding and line breeding.
(i) Inbreeding: This is the mating of two animals of the same breed and species for reproduction purpose. It is carried out where the desired qualities are acquired in the animals to prevent alternation of genetic traits. Animals involved in this process are genetically similar. Inbreeding tends to preserve the traits or qualities of the same animal species without a marked alteration. For example, mating of N’Dama cattle helps to preserve the breed characteristics. Thus, offspring that result from this mating process retains the high resistance of the animal to trypanosomiasis disease.
(ii) Out breeding: This involves mating of different breeds of animals but of the same species to produce offspring. It is important where the different breeds have desired traits. Out breeding is a method of animal improvement where crossing of different breeds of animals is practiced to obtain an improved variety or hybrid. Out breeding normally produces animals with large body size and healthy vigour. Therefore, these animals tend to be more resistant to disease and stress in the environment. The offspring of out breeding are referred to as hybrids, because the qualities of different animals are combined to produce the offspring.
(iii) Line breeding: This is a method of animal improvement in which a number of traits, which are inherent in closely related animals of the same breed are considered as unique characteristics in respect to some characteristics to produce a new variety of animals. It is these vast traits in the line that are combined together to obtain the desired traits in the process of animals’ improvement. In line breeding, a number of traits that have been proven in the parents are chosen in respect to some characters or group of characters. The incessant breeding using line breeding may cause some traits to be depressed due to the constant desire for a single trait in animal improvement.
(iv) Crossbreeding: This is a method of animal improvement in which animals of different breeds within the same species are mated to produce the offspring. It is a form of out crossing and helps to bring together quality traits from different breeds together in the crossbreed offspring for improved production.
(v) Backcrossing: This is a process of animal improvement by mating offspring of different breeds with parent stock to produce backcross offspring. This is important in upgrading of local stock since the first crossbreed offspring are mated back to the exotic parent mates.
Crossbreeding tends to improve desired traits in animals. It helps to produce offspring that are resistant to environmental conditions and pathogenic diseases and pest attacks. Crossbreed offspring mature earlier when compared with their parent stock. It leads to high quality of animals because local breeds of animals tend to be upgraded. Santa Gertrude is an excellent beef cattle produced by crossing the English Short Horn and Brahman; an India breed, resistant to tick, insect and parasites. It grows well when fed on coarse grass. It is well adapted to arid and hot humid areas.
This is a method of animal improvement in which the semen or gametes scientifically collected from male exotic breeds are introduced into the female oviduct of the indigenous breed during heat period to facilitate rapid fertilisation of the female gametes (eggs).
This sexual reproduction process, involves the transfer of the spermatozoa collected from a desired exotic breed from one region to another so as to upgrade the quality of the local breeds. This method of animal improvement can be carried out either manually or mechanically.
Mendelian’s law of Inheritance
Gregor Mendel, an Austrian Monk, is one of the renowned scientists. Mendel was also one of the pioneer scientists in genetics. The basic laws of genetics were first made known by Gregor Mendel.
The transmitted factor is the gene, which is made up of Deoxyribonucleic acid (DNA). The work of Mendel in genetics was first published in 1867. These laid down the basic laws of genetics.
Principle of Mendelian inheritance or Mendel’s law of heredity. The two laws propounded are: The law of segregation (genes) and the law of independent assortment (genes).
Mendel’s first law
Law of segregation (of genes). The law states that inherited factors (genes) are independently transmitted from parents to offspring discretely without any change.
The Mendelian law can be explained with an example; a tall breeding animal is crossed with a dwarf-breeding animal. The result of the first filial generation (F1) showed that all the offspring were tall. Again, when the offspring obtained in the first filial generation are further crossed among themselves, the result of the second filial generation (F2) revealed a ratio of three tall offspring to one dwarf offspring. Mendel’s law can clearly be explained using the process of meiotic cell division.
The understanding here is that each character is governed by a pair of genes called alleles,that is, Aa.
Law of independent assortment:
This is also called Mendel’s second law: The law states that during gamete formation in meiotic cell division, the way each pair of alleles for a given trait distributes into separate gametes tends to be inherited independently of any other allelic pair or characters. This law can be illustrated through the use of true breeding animals. For example, animals that are tall and coloured with other true breeding animals that are dwarfish and colourless.
The first filial generation revealed that all the offspring were tall and coloured. On further crossing of the first filial generation, the result obtained showed that sixteen offspring were produced and of this number, nine were tall and coloured, three were tall and colourless, while three were dwarfish and coloured and only one was dwarfish and colourless.
Rangeland is large hectares of land in which forage crops or pasture are cultivated mainly for livestock. It is usually fenced. Forage crops are grasses and legumes. Grasses supply energy while legumes supply proteins to the grazing animals. The methods of rangeland management include good irrigation schedule, rotational grazing, fertiliser application, rouging tillage, weed control, mulching, liming, reseeding, thinning, maturing and good drainage system.
The major importance of rangeland management is that it ensures regular supply of forage to livestock throughout the year. The methods of animal improvement include Introduction, Quarantine, Selection, and Breeding. The breeding systems are inbreeding, out breeding, Line breeding, crossbreeding, and artificial insemination.
The major aims of animal improvement are to produce healthy animals with good qualities.