(a) Write short notes on the following systems of breeding: (i) In-breeding; (ii) Line-breeding; (iii) Cross-breeding
(b) State three methods of collecting semen from a proven male for use in artificial insemination.
Explanation
(a) In-breeding (i) This involves the mating of more closely related animals than the average of the population from which they come e.g. mating father to daughter, son to mother or brother to sister. (ii) It produces offsprings with undesirable characteristics because of recessive genes showing up. (iii) It also enables the farmer to get desired character or quality well developed in an animal. (iv) in-breeding helps to produce inbred lines that can be used for cross breeding to produce hybrid vigour. (v) It also leads to in-breeding depression.
(ii)Line-breeding (i) It is closely related or similar to in-breeding. (ii) It involves the mating of not too closely-related animals e.g. matings between cousins. (iii) It has the same disadvantage as in-breeding but it takes a longer period for undersirabie trait of the pare to appear (i.e in-breeding depression) (iv) used to consolidate traits fora sire or dam. Most of the high quality commercial characters developed recently have been as a result of line-breeding
(iii)Cross-breeding: (i) This is the mating of pro) quality animals from different breeds. (ii) It may lead to an increase in hybrid vigour, e.g. the cross between mature breed of cattle which is resistant to trypanosomiasis and white Fulani which is susceptible to the disease, to produce a hybrid which combines the good qualities of the two breeds. (iii) It results in breeds of animals with higher production capacity than any of the parents. (iv) It brings about greater rate of growth in an offspring. (v) It produces individuals that can withstand climatic variations in the environment. (vi) It increases disease resistance in offsprings. (vii) It also promotes higher yield of eggs, meat and milk in offspring.
(b) Methods of collecting semen from .a proven male for u in artificial insemination are: (i) artificial vagina (ii) massage method (iii) electro-ejaculation (iv) recovery of semen from the vagina after service.