Foam-Based Mass Emergency Depopulation of Floor-Reared Meat-Type Poultry Operations

Abstract

Current control strategies for avian influenza and other highly contagious poultry diseases often include quarantine, depopulation, and disposal of infected birds. For biosecurity reasons, on-farm depopulation and disposal methods are preferred. The options for mass depopulation are limited, as reported by the "2000 Report of the AVMA Panel on Euthanasia." Current depopulation techniques may have excessive labor requirements, are not appropriate for all house types, and may not be suitable for large-scale emergency implementation. A procedure has been developed that uses foam to rapidly form a blanket over the birds. The procedure requires relatively few people, can be performed in a variety of house types, and is compatible with in-house composting. Results from 2 experiments using foam for depopulation are presented in this paper. These studies have shown that foams are comparable to the CO(2) polyethylene tent procedure in time to death in small groups and that the foam is faster as group size increases. Adding CO(2) to the foam does not enhance its efficacy. Based on corticosterone levels, the study also showed that the foams are no more stressful than the CO(2) depopulation method. Necropsy and histological examination of birds indicated that blood was present to some degree in the trachea, syrinx, and bronchial tree in broilers subjected to foam with CO(2), foam without CO(2), and CO(2) polyethylene tent methods of depopulation. Foam caused a rapid onset of airway occlusion. In both foam- and CO(2)-euthanized broilers, lesions are consistent with anoxia or hypoxia. This suggests that foam acts by physically induced hypoxia, whereas CO(2) causes chemically induced hypoxia.

A mobile modified-atmosphere killing system for small-flock depopulation

“…Separate gas delivery systems were installed so that CO 2 or N 2 could be injected into the chamber from cylinders mounted at the front of the trailer. Gas sensors for CO 2 [10] or O 2 [11], electronically connected, respectively, to the CO 2 or N 2 delivery system, sampled the atmosphere inside the chamber on a continuous basis during operation. Each sensor controlled a solenoid valve [12], triggering it to release gas to modify the internal atmosphere according to a preset target gas concentration.…”

“…Number of birds observed is given in parentheses. 2 Manual control of CO 2 injection into chamber. 3 An additional 33 birds did not perform head shaking.…”

“…into which birds can be driven and gassed [1]; by covering birds with fire-fighting foam [2]; by placing transport modules of birds into specially designed containers and injecting gas [3]; or by whole-house gassing [4].…”

“…Performance of the modified-atmosphere killing system using N 2 with 51-d-old broilers Time from the start of N 2 injection into the chamber until the end of wing flapping after loss of posture + 30 s 2. Sum of means for load layers 1 and 2.…”

“…Carbon dioxide used during trials of the modified-atmosphere killing system used per ton or tonne of BW 2. Includes a partial load not recorded inTable 1.…”