Principles of Genetics and Breeding

Problems

1. Calculate the Effective Breeding Number (Ne) if 53 females and 25 males were used for breeding. What will be the effective breeding number if the sex ratio is 1:1.

2. If a farmer wants an Ne=100, if 75% of the fish spawn, if 95% of those that spawn produce viable offspring, and if survival from the time brood fish are set aside until they are spawned is 70%, determine the number of brood fish that the farmer has to maintain.

3. How will you determine the size of the ponds that are needed in a selective breeding programme to have 200 select brood fish with the following given condition.

Cut-off at food fish harvest: select top 10%

Cut-off at fingerling harvest: select top 50%

Fry-fingerling mortality: 50%

Fingerling-food fish mortality: 10%

Stocking density in fingerling pond: 200,000/ha

Stocking density in food fish pond: 7,000/ha

4. How to predict the response to selection if the heritability (h²) of the phenotype is known. Predict response to selection for increased length and then calculate the predicted mean length of the next generation.

Given: h² for length at 12 months = 0.26
h² for length at 12 months = 0.26
mean length at 12 months of the population = 146 mm
mean length at 12 months of the select brood fish = 162 mm

5. How to use a control population to assess the results of selection.

Calculate the total improvement.

(Tagging under selective breeding)

	Given: mean length of the P1 generation = 150 mm
	mean length of the F1 select generation = 165 mm
	mean length of the F1 control generation = 159 mm