ANSM412 _Assignment_2_2021
Due date: 15 APRIL 2021
Instructions: Type the assignment using MS-Word and name the file
(Surname_studentNo_Ass2). Upload the assignment script on or before the due date to Dropbox
under your name folder. Please, don’t convert your assignment script to PDF file. Also, don’t
forget to write your name and student number on the cover page.
Question 2 [29]
Let you assume that beef cattle weaning weight is affected by six loci genes. The genotype or
the genetic make of 7 bulls for these six loci is as shown in the table below. Further assume
the following conditions are also true:
There is no epistasis effect on weaning weight.
Each dominant type allele regardless of loci contribute +4 kg and each recessive allele
contribute -2 kg to the weaning weight.
The environmental deviation contributions to the phenotype of each bull is as shown
in the table.
Regardless of loci type, over-dominance relationship exists between heterozygous
alleles and each heterozygous gene pair contributes 12 kg to the genotype.
The population mean weaning weight (µ) is 200 kg.
ID Genotype BV G GCV E P
(G-BV)
1 AABBCCDDEEFF -10
2 AaBbCcDdEeFf 12 72 60 -2 270
3 AABbCcddEeFf 0
4 AAbbCcDDeeFf +2
5 AAbbCCddEEFF +3
6 AaBBCCDdEeff -3
7 aabbccddeeff +4
Where BV = breeding value, G=genotypic value; GCV= gene combination value,
E=environmental deviation.
P= μ + G + E; Or P= μ + BV + GCV + E
Worked out example for animal 2: BV= 6(6) + 6(-2) = 12; G=6(12)=72; GCV=72-12=60, there
for predicted phenotypic value of animal 2 is P=200+ 72 + -2 = 270.
Based on the information provided, answer the following questions
A. Complete the missing values in the table [9]
B. Which animals is phenotypically the heaviest at weaning? [2]
1
, C. Which animal will produce the heaviest progeny at weaning? [2]
D. Which animal has the highest breeding value (BV)? [2]
E. Which animal has the highest gene combination values (GCV)? [2]
F. Which animal has the highest favourable gene combinations for weaning weight? [2]
G. Which animal has the highest unfavourable gene combinations for weaning
weight? [2]
H. Which animal suffers from inbreeding depression the most? [2]
I. Which animal has favoured the most from hybrid vigour or heterosis? [2]
J. Assume that animal 2 is the progeny of animal 1 and 7. After correcting the phenotypic
values of the progeny and the parents for the environmental deviations. Calculate
direct heterosis (in percent) for the weaning weight of the progeny (Animal 2) [4]
Question 3 [27]
The values shown in the table below are extracted from Williams et al. (2010) report on
weaning weight of selected beef cattle crossbreds. The overall population mean weaning
weight reported was 270 kg. Assume for all types of crosses between breeds, the reported
individual and maternal heterosis are valid. In the mating design shown below the sire
genotype is written first on the left and dam genotype on the right of the "X" mark. For
crossbreds involving more than one breed in either sire or dam side, a bracket is used for the
sire and dam genotypes. In two breed crossing, if a crossbred genotype constituted from equal
contributions of the two breeds involved in the crossbreeding, then the crossbred individual is
the first generation cross (F1). In two breed crossing, if one breed has highest contributions to
the genotype of the crossbred individual, then that crossbred individual is produced by
backcrossing to the breed with highest contributions. In a three-breed crossing, the breed with
the highest contributions to the genotype of crossbred individual is the last used sire breed.
Breed Direct breed (kg) Maternal breed (kg)
Angus (A) 0 0
Hereford (H) 4.3 -11.4
Charolais (C) 24.3 9.6
Limousin (L) 11.4 0.5
Simmental (S) 28.0 14.0
Brahman (B) -3.2 6.6
Heterosis (%) 15 10
NB: The first letter of breed name is used represent the breed genotype in the mating shown
below.
What is the predicted weaning weight performance of the progeny from the following mating?
a) BxB [3]
b) (1/2A1/2B) x (1/2C1/2L) [3]
2
Due date: 15 APRIL 2021
Instructions: Type the assignment using MS-Word and name the file
(Surname_studentNo_Ass2). Upload the assignment script on or before the due date to Dropbox
under your name folder. Please, don’t convert your assignment script to PDF file. Also, don’t
forget to write your name and student number on the cover page.
Question 2 [29]
Let you assume that beef cattle weaning weight is affected by six loci genes. The genotype or
the genetic make of 7 bulls for these six loci is as shown in the table below. Further assume
the following conditions are also true:
There is no epistasis effect on weaning weight.
Each dominant type allele regardless of loci contribute +4 kg and each recessive allele
contribute -2 kg to the weaning weight.
The environmental deviation contributions to the phenotype of each bull is as shown
in the table.
Regardless of loci type, over-dominance relationship exists between heterozygous
alleles and each heterozygous gene pair contributes 12 kg to the genotype.
The population mean weaning weight (µ) is 200 kg.
ID Genotype BV G GCV E P
(G-BV)
1 AABBCCDDEEFF -10
2 AaBbCcDdEeFf 12 72 60 -2 270
3 AABbCcddEeFf 0
4 AAbbCcDDeeFf +2
5 AAbbCCddEEFF +3
6 AaBBCCDdEeff -3
7 aabbccddeeff +4
Where BV = breeding value, G=genotypic value; GCV= gene combination value,
E=environmental deviation.
P= μ + G + E; Or P= μ + BV + GCV + E
Worked out example for animal 2: BV= 6(6) + 6(-2) = 12; G=6(12)=72; GCV=72-12=60, there
for predicted phenotypic value of animal 2 is P=200+ 72 + -2 = 270.
Based on the information provided, answer the following questions
A. Complete the missing values in the table [9]
B. Which animals is phenotypically the heaviest at weaning? [2]
1
, C. Which animal will produce the heaviest progeny at weaning? [2]
D. Which animal has the highest breeding value (BV)? [2]
E. Which animal has the highest gene combination values (GCV)? [2]
F. Which animal has the highest favourable gene combinations for weaning weight? [2]
G. Which animal has the highest unfavourable gene combinations for weaning
weight? [2]
H. Which animal suffers from inbreeding depression the most? [2]
I. Which animal has favoured the most from hybrid vigour or heterosis? [2]
J. Assume that animal 2 is the progeny of animal 1 and 7. After correcting the phenotypic
values of the progeny and the parents for the environmental deviations. Calculate
direct heterosis (in percent) for the weaning weight of the progeny (Animal 2) [4]
Question 3 [27]
The values shown in the table below are extracted from Williams et al. (2010) report on
weaning weight of selected beef cattle crossbreds. The overall population mean weaning
weight reported was 270 kg. Assume for all types of crosses between breeds, the reported
individual and maternal heterosis are valid. In the mating design shown below the sire
genotype is written first on the left and dam genotype on the right of the "X" mark. For
crossbreds involving more than one breed in either sire or dam side, a bracket is used for the
sire and dam genotypes. In two breed crossing, if a crossbred genotype constituted from equal
contributions of the two breeds involved in the crossbreeding, then the crossbred individual is
the first generation cross (F1). In two breed crossing, if one breed has highest contributions to
the genotype of the crossbred individual, then that crossbred individual is produced by
backcrossing to the breed with highest contributions. In a three-breed crossing, the breed with
the highest contributions to the genotype of crossbred individual is the last used sire breed.
Breed Direct breed (kg) Maternal breed (kg)
Angus (A) 0 0
Hereford (H) 4.3 -11.4
Charolais (C) 24.3 9.6
Limousin (L) 11.4 0.5
Simmental (S) 28.0 14.0
Brahman (B) -3.2 6.6
Heterosis (%) 15 10
NB: The first letter of breed name is used represent the breed genotype in the mating shown
below.
What is the predicted weaning weight performance of the progeny from the following mating?
a) BxB [3]
b) (1/2A1/2B) x (1/2C1/2L) [3]
2
