Abstract
A state-transition model was developed to describe transitions between states of immunity and health among age
classes (days) in populations of neonate chicks. Immunity was defined as a function of maternal immunity (MI),
innate immunity (II), and acquired immunity (AI), while health was defined as susceptible, infected, resistant,
recovered or dead. Probability functions were used to describe transitions at immunity-, and health state level.
Four scenarios were set up, varying genetic aptitudes for MI (a line with high (HMI) and a line with low MI
(LMI)) and time of challenge (1 or 3 weeks of age). HMI expressed a higher antibody (AB) level (MI+AI) than
LMI at 1 week post challenge when challenged at 1 week of age. The ranking of lines would be highly
influenced by the correlation between the level of MI and the genetic abilities of the dam for mounting an AB
response though, and ranking of intermediate lines would be less apparent due to the counteracting effect of MI
on AI. Between-line variation and ranking of lines based on differences in health state following challenge at 1
week of age was in agreement with that based on differences in AB measurements. The AB level (MI+AI)
following challenge at 3 weeks of age was almost equal at any age post challenge. The between-line variation in
health states, on the other hand, was much larger when challenge was at 3 weeks of age than 1 week of age.
In conclusion, the assessment of between-line variation would be most reliable based on challenge at 1 week of
age measuring AB level, corrected for maternal AB, 1 week post challenge.
classes (days) in populations of neonate chicks. Immunity was defined as a function of maternal immunity (MI),
innate immunity (II), and acquired immunity (AI), while health was defined as susceptible, infected, resistant,
recovered or dead. Probability functions were used to describe transitions at immunity-, and health state level.
Four scenarios were set up, varying genetic aptitudes for MI (a line with high (HMI) and a line with low MI
(LMI)) and time of challenge (1 or 3 weeks of age). HMI expressed a higher antibody (AB) level (MI+AI) than
LMI at 1 week post challenge when challenged at 1 week of age. The ranking of lines would be highly
influenced by the correlation between the level of MI and the genetic abilities of the dam for mounting an AB
response though, and ranking of intermediate lines would be less apparent due to the counteracting effect of MI
on AI. Between-line variation and ranking of lines based on differences in health state following challenge at 1
week of age was in agreement with that based on differences in AB measurements. The AB level (MI+AI)
following challenge at 3 weeks of age was almost equal at any age post challenge. The between-line variation in
health states, on the other hand, was much larger when challenge was at 3 weeks of age than 1 week of age.
In conclusion, the assessment of between-line variation would be most reliable based on challenge at 1 week of
age measuring AB level, corrected for maternal AB, 1 week post challenge.
| Original language | English |
|---|---|
| Title of host publication | Proceedings World's Poultry Congress 2004, Istanbul,Turkey,8-13 June 2004. |
| Number of pages | 5 |
| Publication date | 2004 |
| Publication status | Published - 2004 |
| Externally published | Yes |
| Event | World's Poultry Congress 2004 - Istanbul, Turkey Duration: 8 Jun 2004 → 13 Jun 2004 |
Conference
| Conference | World's Poultry Congress 2004 |
|---|---|
| Country/Territory | Turkey |
| City | Istanbul |
| Period | 08/06/2004 → 13/06/2004 |