Broiler lines divergently selected for digestive efficiency also differ in their susceptibility to colibacillosis

Area of Science:

• Animal Science
• Genetics
• Poultry Health

Background:

• Selective breeding aims to enhance broiler chicken feed efficiency, reducing costs and environmental impact.
• Divergent selection created two broiler lines (D+/D-) with distinct digestive tract anatomy, histology, and gut microbiota.
• Colibacillosis, caused by avian pathogenic *Escherichia coli*, is a major economic concern in poultry production.

Purpose of the Study:

• To investigate the effect of divergent selection for digestive efficiency on broiler chicken susceptibility to colibacillosis.
• To determine if genetic selection for improved digestion influences disease resistance.

Main Methods:

• Two broiler chicken lines (D+/D-) divergently selected for digestive efficiency were used.
• Chickens were challenged with an avian pathogenic *Escherichia coli* strain in two experiments.
• Experiment 1: Assessed 50% lethal dose via subcutaneous infection of hatchlings.
• Experiment 2: Reproduced colibacillosis by infecting air sacs of 23-day-old chicks.

Main Results:

• The 50% lethal dose of *E. coli* was low in both broiler lines.
• Broiler chickens from the D+ line, selected for higher digestive efficiency, exhibited lower susceptibility to colibacillosis.
• Significant differences in disease resistance were observed between the divergently selected lines.

Conclusions:

• Higher digestive efficiency in broiler chickens is associated with increased resistance to colibacillosis.
• This finding supports the potential for using digestive efficiency as a selection criterion to improve disease resistance in poultry.
• Integrative genetic studies can explore the complex interactions between digestive efficiency and disease resistance in broiler chickens.