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Divergent selection for ascites incidence in chickens
H O Pavlidis1, J M Balog, L K Stamps
1Department of Poultry Science, University of Arkansas, Fayetteville 72701, USA.
Poultry Science
|November 22, 2007
Summary
Developing chicken lines resistant or susceptible to ascites syndrome through hypobaric chamber selection rapidly altered disease incidence. Direct selection for ascites resistance improved livability but reduced body weight, necessitating balanced breeding strategies.
Area of Science:
- Animal Science
- Genetics
- Poultry Breeding
Background:
- Ascites syndrome is a significant concern in poultry production, often exacerbated by high-altitude conditions.
- Previous breeding strategies have shown varying success in managing ascites incidence.
- Understanding the genetic basis and heritability of ascites is crucial for effective selection programs.
Purpose of the Study:
- To develop and characterize chicken lines divergently selected for resistance and susceptibility to ascites syndrome.
- To evaluate the effectiveness of selection on ascites incidence, livability, and body weight.
- To assess the utility of the right ventricle:total ventricle (RV:TV) ratio as a selection indicator for ascites.
Main Methods:
- Utilized a hypobaric chamber to simulate high-altitude conditions and induce ascites syndrome.
- Employed divergent selection based on ascites mortality data across multiple generations.
- Measured ascites incidence, livability, body weight (BW), and RV:TV ratio in selected lines.
Main Results:
- Rapid divergence was achieved, with susceptible (SUS) lines reaching 95.1% ascites incidence and resistant (RES) lines reaching 7.1% incidence.
- Selection for ascites resistance (RES line) increased livability by 11.5 days, while susceptibility (SUS line) decreased it by 8 days.
- Negative genetic correlations between ascites and RV:TV ratio were observed, but the ratio showed no significant change under normal conditions, questioning its validity as an indicator trait.
Conclusions:
- Direct selection using sire family performance is effective in reducing ascites incidence in chickens.
- Selection for ascites resistance negatively impacts body weight, requiring simultaneous selection for BW to maintain economic traits.
- The RV:TV ratio may not be a reliable indicator for selecting against ascites under all conditions.
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