Depopulation of Caged Layer Hens with a Compressed Air Foam System

Abstract

Simple SummaryReportable diseases, such as avian influenza, spread rapidly among poultry, resulting in the death of a large number of birds. Once such a disease has been diagnosed at a farm, infected and susceptible birds are rapidly killed to prevent the spread of the disease. The methods to eliminate infected caged laying hens are limited. An experiment was conducted to study the effectiveness of foam made from compressed air, water, and soap to kill laying hens in cages. The study found that stress levels of the hens killed using compressed air foam in cages to be similar to the hens killed by carbon dioxide or the negative control. Hens exposed to carbon dioxide died earlier as compared to the foam methods. The authors conclude that application of compressed air foam in cages is an alternative to methods such as gas inhalation and ventilation shutdown to rapidly and humanely kill laying hens during epidemics.AbstractDuring the 2014–2015 US highly pathogenic avian influenza (HPAI) outbreak, 50.4 million commercial layers and turkeys were affected, resulting in economic losses of $3.3 billion. Rapid depopulation of infected poultry is vital to contain and eradicate reportable diseases like HPAI. The hypothesis of the experiment was that a compressed air foam (CAF) system may be used as an alternative to carbon dioxide (CO2) inhalation for depopulating caged layer hens. The objective of this study was to evaluate corticosterone (CORT) and time to cessation of movement (COM) of hens subjected to CAF, CO2 inhalation, and negative control (NEG) treatments. In Experiment 1, two independent trials were conducted using young and spent hens. Experiment 1 consisted of five treatments: NEG, CO2 added to a chamber, a CO2 pre-charged chamber, CAF in cages, and CAF in a chamber. In Experiment 2, only spent hens were randomly assigned to three treatments: CAF in cages, CO2 added to a chamber, and aspirated foam. Serum CORT levels of young hens were not significantly different among the CAF in cages, CAF in a chamber, NEG control, and CO2 inhalation treatments. However, spent hens subjected to the CAF in a chamber had significantly higher CORT levels than birds in the rest of the treatments. Times to COM of spent hens subjected to CAF in cages and aspirated foam were significantly greater than of birds exposed to the CO2 in a chamber treatment. These data suggest that applying CAF in cages is a viable alternative for layer hen depopulation during a reportable disease outbreak.

Evaluation of Two Compressed Air Foam Systems for Culling Caged Layer Hens

“…The two experiments reported here, in connection with Gurung et al [ 17 , 18 ], illustrate that the mean differences in time to COM depend on implementation (Experiment 1 = 211 s, Experiment 2 = 165 s, Gurung et al = 195 s). The equipment used in Experiment 1 and that used by Grunung et al [ 17 ] was similar; however, there were differences in implementation. In Experiment 2, foam was applied from both sides of the cage simultaneously, which may result in a more rapid cage fill time.…”

“…Two different types of CAFS, with and without CO 2 , were able to depopulate caged layer hens, something that other types of foam depopulation were not able to achieve. The results of this project complemented Gurung et al [ 17 , 18 ], who documented the effectiveness of CAFS, but did not assess unconsciousness.…”

“…The foam was created using a custom compressed air foam system consisting of a mixing chamber for ambient air and CO 2 that was used to inject a specific amount of CO 2 gas or air into the foam to keep concentrations consistently at the set amount [ 17 , 18 ]. To produce large enough quantities of CO 2 gas and to create foam with CO 2 gas, this system was equipped with a 25 kW generator to supply three-phase power to a Thermax H3L vaporizer (Thermax, Dartmouth, MA, USA).…”

“…For CAFS with CO 2 , the same equipment was used to create the foam as previously described. However, for this treatment, a CO 2 evaporator trailer equipped with a manifold was used to inject CO 2 gas into the foam [ 17 , 18 ]. The CO 2 gas application rate was 288 slpm at 580 kPa and the air application rate was 1100 slpm at 580 kPa.…”

“…CAFS also have a higher retention time than the other types of foam tested [ 7 ], which provides a higher retention time in objects such as animal cages. Gurung et al [ 17 ] found that CAFS with N 2 resulted in faster time to motion cessation. Gurung et al [ 18 ] found that CAFS with and without inert gas resulted in similar bird stress levels.…”