|Dozier Iii, William|
Submitted to: International Journal of Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2008
Publication Date: 9/15/2008
Citation: Olanrewaju, H.A., Dozier III, W.A., Purswell, J.L., Branton, S.L., Miles, D.M., Lott, B.D., Pescatore, A.J., Thaxton, J.P. 2008. Growth performance and physiological variables for broiler chickens subjected to short-term elevated carbon dioxide concentrations. International Journal of Poultry Science. 7(8):738-742.
Interpretive Summary: Costs for fuel and electricity have increased dramatically in recent years, spurring growers to adopt energy conservation measures such as reduced ventilation during winter months to conserve fuel. Modern poultry housing is designed and constructed to reduce heat loss and improve energy efficiency, however when coupled with reduced ventilation, can result in elevated levels of carbon dioxide, ammonia, and other air contaminants, which may adversely affect the health and productivity of flocks. Air quality is essential to getting chicks off to a good start, but carbon dioxide concentrations may often exceed 3,000 ppm during brooding in modern housing as a result of reduced ventilation. Subjecting broiler chickens to elevated carbon dioxide concentrations early during grow-out may adversely affect subsequent livability. In addition, pulmonary hypertension syndrome is associated with high partial pressure of carbon dioxide and low partial pressure of oxygen values in the blood. The present study examined responses of broiler chickens subjected to various concentrations of carbon dioxide from 1 to 14 days of age on subsequent blood physiological variables, heart characteristics, growth performance, and the incidence of mortality during a 42 day production period. Our result indicated that subjecting chicks to higher levels of carbon dioxide during the brooding period did not alter blood physiological variables and cumulative growth performance, but increased the incidence of late-mortality. This tolerance to high carbon dioxide suggests that the chickens have adaptation mechanisms to counteract the imposed excess of carbon dioxide in the blood to a certain level. The results of this study show the positive impact on profits to modern commercial poultry housing that are using reduced ventilation during winter months and brooding period to conserve fuel, reduce energy costs, thereby producing animal protein at low cost to the taxpayer without any major measurable effects on overall poultry welfare and environment.
Technical Abstract: Four trials were conducted to evaluate growth responses, blood chemistry and heart characteristics of broiler chicks subjected to progressive concentrations (0, 3,000, 6,000, 9,000 ppm) of carbon dioxide (CO2) gas from 1 to 14 days of age, which were then discontinued throughout the remainder of the trial (42 days of age). On days 14 and 42 of each trial, 20 birds per chamber were randomly selected for immediate analysis of blood partial pressure of CO2 (pCO2), blood partial pressure of O2 (pO2), blood pH, hematocrit (Hct), hemoglobin (Hb), blood electrolytes (Na+, K+, Ca2+, and Cl-), and determination of heart characteristics. Body and feed weights were recorded at 0, 14, 28 and 42 days of age for growth performances. Final body weight (BW) gain and feed conversion were similar among the treatments, but cumulative mortality significantly increased as CO2 increased (P = 0.05) from 3,000 to 9,000 ppm. Treatments did not alter blood pCO2 and pO2 concentrations at age 14 and 42 days of age. Increasing CO2 up to 9,000 ppm failed to reveal differences for heart weight characteristics at 14 days of age, but total heart and left ventricle weights were increased at 42 days of age. These results indicate that subjecting chicks to progressive concentrations of CO2 from 1 to 14 days of age does not adversely alter blood chemistry or cumulative growth performance, but increased the incidence of late-mortality.