D2: Most common genetic diseases of poultry species, defects as conformation traits

Question 1

what is a genetic disorder?

Answer 1

A genetic disorder is a genetic problem caused by one or more abnormalities formed in the genome.
* Genetic disorders may be hereditary, passed down from parental genes.
* In other, defects may be caused by new mutations or changes to the DNA.

Question 2

What is gout?

Answer 2

Gout: form of inflammatory arthritis characterized by recurrent attacks or a red, tender, hot and
swollen joint.

◦ Disease due to persistently elevated levels of uric acid in the blood.

◦ It’s partly due to genetics, contributing to about 60% variability in uric acid level.

◦ Loss-of-function mutation in SLC2A9 cause low blood uric acid levels by reducing urate absorption.

Question 3

name some poultry diseases

Answer 3

caolibacillosis
pasteurellosis
salmonellosis
mareks disease
fowl pox
avian influenza
new castle disease

Question 4

what is colibacillosis

Answer 4

→ infectious disease caused by bacterium Escherichia Coli (AKA E. Coli)

Question 5

what is pasteurellosis?

Answer 5

bacterial infection that’s contagious; caused elevated mortality, lameness, swollen wattles (in Chicken), pneumonia (in Turkey) & torticollis

Question 6

what is salmonellosis

Answer 6

infection caused by the genus Salmonella.

◦ Causing serious economic losses to the poultry industry in terms of mortality, reduced growth,
loss of egg production.

Question 7

what is mareks disease?

Answer 7

highly contagious viral nepoplastic disease in chickens;
named after a Hungarian veterinarian József Marek (Symptoms: paralysis in the wings, legs & neck; visible loss in weight; irregular shaped pupil or grey iris; a collapsed crop)

Question 8

what is fowl pox

Answer 8

→ relatively slow-spreading viral infection (occurs in both wet & dry form → the wet form is characterized by plaques in the mouth & upper respiratory tract).

Question 9

what is avian influenza

Answer 9

virus through direct contact with infected waterfowl/infected poultry (fever,muscle aches, sore throat, conjunctivitis - eye infections)

Question 10

what is new castle disease

Answer 10

acute respiratory disease (depression, nervous manifestation, diarrhea)

Question 11

what are the 5 stages of lethal mutations?
give examples of the traits related to the lethal mutation.

Answer 11

1) obligate recessive: the homozygotes are too
abnormal to develop and hatch.
Example: chondrodystrophy, wingless, duck beak.

2) Obligate semilethal: acts usually during
embryonic life, varies between 50 and 100 percent according to the environment and/or modifying genes.
Example: albinism, shankless.

3) Facultative lethal: individuals do not survive well, and special effort must be made to keep mortality at minimum.
Example: sleepy eye, crooked neck.

4) Posthatch obligate lethal: it may even be lethal as late as adulthood.
Example: shaker

5) sex-linked: chondrodystrophy

Question 12

name 2 z-linked genes (male sex linked)

Answer 12

1) barring; broader in male than females.
2) recessive white skin mutation: (yy males show lighter blood plasma colouration than others).

Question 13

monogenic characteristics: single gene variation.
mention some of these characteristics in relation to poultry species.

Answer 13

• comb form: autosomal dominant.
• frizzleness: autosomal dominant.
• lacking feather roots: autosomal dominant, Rhode Island Red.
• tailess: autosomal dominant
• henny feathering in cocks: incomplete dominant.
• shank feathering (legs): autosomal dominant.
• earlobe colour: mainly red, white in some mediterranean breeds.
• silky feather: autosomal recessive .
• frayed feathering: autosomal recessive.
• featherless: recessive, Z-linked.
• naked neck: autosomal intermediate.
• crested: autosomal recessive (augsburg breed)

Question 14

monogenic characteristics: genetic defects

Answer 14

• Chondrodystrophy: Creeper gene, dominant, homozygotes: lethal for embryos;
  heterozygotes: excellent egg production;
  breeding: 1/4 normal, 2/4 creeper, 1/4 embryonic
  lethal.
• Dwarfism (dw): recessive, in many Asiatic dwarf
  breeds, Bantam.
• 5-toe character: in Dorking; oldest breed of
  England; typical in Silkies; inherited by crossings
• Brachydactyly - By gene (autosomal
  incomplete dominant).
• leucism: is a condition in which there is (partial) loss of pigmentation in an animal resulting in white, pale, or patchy coloration of the skin, hair, feathers, scales or cuticle, but not the eyes. Unlike albinism, it is caused by a reduction in multiple types of pigment, not just melanin.