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Faculty of Graduate Studies Master program in animal production Advanced Animal Breeding (495523) First Exam Date: 14/4/2009 Instructor: Dr. Jihad ABDALLAH Name: Q1. (10 POINTS) Answer the following with True or False: 1. --------- Dystocia is an example of a simply inherited trait. 2. --------- Breeding value of an individual is the mean deviation of its progeny from the population mean. 3. --------- In progeny testing, the accuracy of prediction of breeding value increases more by doubling the number of records per progeny than doubling the number of progeny. 4. --------- Producing ability measures the ability of the animal to repeat its performance in future records. 5. --------- Standard error of the heritability estimate from the regression of offspring on one parent is equal to the standard error of the regression coefficient. 6. --------- At a biallelic locus with no dominance, the additive variance is maximum when allele frequency is 0.5. 7. --------- Three-factor interaction arises from interaction between alleles on three loci. 8. --------- Heritability estimate from offspring-dam regression is generally larger than that estimated from offspring-father regression. 9. --------- It is more accurate to evaluate the breeding value of a bull using m half-sib progeny than using m of the half sibs of the bull 10. ---------- The genetic covariance between half-sibs is equal to half the additive variance. Q2. a) (2 POINTS) Mention two differences between simply inherited traits and polygenic traits b) (2 POINTS) What does heritability in the narrow sense measure? c) (3 POINTS) Give an example on each of the following: 1- A trait with low heritability: 2- A trait with moderate heritability: 3- A trait with high heritability: 1 Q3. (8 POINTS) The following are mean genotypic values at a single locus: Genotype aa Aa AA Genotypic value 40 60 60 Assuming that q (the frequency of allele a) is 0.4 a) Find the overall mean of the population. b) Average effect of each allele and average affect of gene substitution c) The breeding value and the dominance deviation for each of the three genotypes. d) The additive and dominance variances. 2 Q4. a) (4 POINTS) the following data were obtained for a repeated trait: Phenotypic variance = 120, Additive variance= 40, Dominance variance = 8, Epistasis variance = 2, and temporary environmental variance =60. If the variance due to maternal and common environmental effects is equal to 0, find: 1. The heritability in the narrow sense 2. The heritability in the broad sense 3. The repeatability b) (5 POINTS) In a progeny test, a dairy bull has 60 paternal half-sib progeny each with a single record. Suppose that the average of milk records on the 60 daughters is 8000 kg and the population average is 6000 kg. Assuming that the heritability of milk yield is 0.30; compute the breeding value of the bull from this information and the accuracy of the prediction. 3 Q5. (6 POINTS) For the following pedigree, calculate the additive relationship coefficients among all the animals using the tabular method. O A C B D 4 Q6. (10 POINTS) Use the following ANOVA table to estimate variance components and heritability. Compute the standard error of the heritability. (Hint: balanced design with 4 sires, 4 dams per sire, and 5 progeny per dam). Source SS MS Expected MS 3 1000 250 E2 2 D2 3 S2 Between dams within sires 12 1200 100 E2 1 D2 Between progeny within dams 64 5760 90 TOTAL 79 7960 Between sires d.f E2 5