|Dozier iii, William|
Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/13/2005
Publication Date: 6/15/2005
Citation: Dozier III, W.A., Lott, B.D., Branton, S.L. 2005. Growth responses of male broilers subjected to increasing air velocities at high ambient temperatures and a high dewpoint. Poultry Science. 84:962-966. Interpretive Summary: In the U.S., 8.8 billion broilers are produced annually. Heat stress conditions during summer production results in significant economic losses to the industry by adversely affecting growth rate and increasing late-mortality incidence. The largest contributor to heat production is the bird itself. Applying air velocity over broilers ameliorates heat stress conditions. While previous research has demonstrated improved broiler growth rate as air velocity increased from 120 to 180 m/min under moderate (25-30-25 C) temperatures, determining growth responses of broilers subjected to air velocity of either 120 or 180 m/min under high temperatures (25-35-25 C) has not been investigated. Results from this research demonstrated that body weight gain was increased by 287 g and provided a 10 point improvement in feed conversion from 21 to 49 days of age when air velocity was increased from 120 to 180 m/min. Contract growers are paid on the basis of live body weight and the 287 g difference in body weight translates to an economic advantage of $0.03 per bird in addition to the savings attributable to improved feed conversion.
Technical Abstract: This study examined live performance responses of male broilers to increasing air velocity of 120 and 180 m/min reared under high cyclic temperatures (25-35-25 C) with a 23 C dewpoint during 21 to 49 d. Birds were reared in an environmental facility containing two wind tunnels (four pens/tunnel) and six floor pens (control). At 21 d, 53 birds were placed in each pen of the wind tunnels and control group, respectively, and growth performance was determined weekly. Increasing air velocity from 120 to 180 m/min improved BW and BW gain from 29 to 35, 36 to 42, and 43 to 49 d of age leading to a cumulative advantage of 287 g in BW gain and a 10 point difference in feed conversion from 21 to 49 d of age. These results indicate that male broilers approximating 2.0 to 3.0 kg respond to an air velocity of 180 m/min when exposed to high cyclic temperatures.