Avian lymphoid leukosis prophylaxis with mibolerone

Area of Science:

• Veterinary Virology
• Poultry Immunology
• Pharmacology

Background:

• Lymphoid leukosis (LL) is a significant concern in poultry farming.
• Rous-associated virus type 1 (RAV-1) is a primary causative agent of LL.
• Effective prophylactic measures against LL are crucial for the poultry industry.

Purpose of the Study:

• To investigate the efficacy of mibolerone in preventing lymphoid leukosis in chickens.
• To determine the optimal dosage and administration period for mibolerone prophylaxis.
• To elucidate the mechanism by which mibolerone affects LL development.

Main Methods:

• Chickens were inoculated with Rous-associated virus type 1 (RAV-1) at one day of age.
• Mibolerone was administered orally at different doses (1 and 4 microng/g of diet) and during specific age periods (days 1-49 or 29-49).
• Incidence of LL was assessed, and bursal lymphocytic follicles were examined histologically.

Main Results:

• Mibolerone at 1 microng/g of diet during the first 49 days significantly reduced LL incidence (P < .005).
• A higher dose (4 microng/g) or later administration (days 29-49) did not reduce LL incidence.
• Histological examination revealed significant atrophy of bursal lymphocytic follicles, more complete with the 1-microng dose during the initial 49 days.

Conclusions:

• Mibolerone administered orally at 1 microng/g of diet during the first 49 days of age shows promise for lymphoid leukosis prophylaxis in chickens.
• The mechanism of action involves early bursal atrophy, targeting key cells involved in LL development.
• Further field trials are warranted to confirm mibolerone's effectiveness under natural infection conditions.