Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/4/2003
Publication Date: 9/1/2003
Citation: BALOG, J.M., KIDD, B.D., ANTHONY, N.B., HUFF, G.R., HUFF, W.E., RATH, N.C. EFFECT OF COLD STRESS ON BROILERS SELECTED FOR RESISTANCE OR SUSCEPTIBILITY TO ASCITES SYNDROME. POULTRY SCIENCE. 2003. V. 82, NO. 9, P. 1383-1387. Interpretive Summary: Two lines of broilers were selected from a common parent line, based on their susceptibility to the poultry disease ascites. The lines were selected using a hypobaric chamber, which simulated high altitude by operating under a partial vacuum to reduce available oxygen. An experiment was conducted to determine the responses of the genetically selected ascites resistant, ascites susceptible, and the relaxed parent lines to cold stress, a known ascites-inducing stressors. When exposed to a cold stress, without any simulated high altitude, the three lines responded as they had under hypobaric stress. Although cold stress did not produce as high an incidence of the disease, the resistant line experienced the least amount of ascites and the susceptible line the most ascites, with the relaxed line being intermediate. Final body weight was the same between the lines, which indicates that selection for ascites resistance or rsusceptibility did not result in a lighter bird, which would have been detrimental. Based on the results, it seems that the lines selected by hypobaric exposure respond in a similar manner to cold stress ascites induction.
Technical Abstract: An ascites resistant and an ascites susceptible line have been developed using sire family selection based on mortality data taken from sibs reared in a hypobaric chamber (simulated 2900m above sea level). The relaxed line is representative of the original commercial pureline stock randomly mated with no selection pressure applied. A study was conducted to evaluate the differences between the lines when reared in floor pens and subjected to a ascites-inducing cold stress. Birds were warm-room brooded for the first two wk, then cold stress was applied at 14**0 C for the remaining 4 wk. Body weights were not significantly different between the resistant, susceptible and relaxed lines (P#0.05). Feed conversion was significantly better in the resistant line when compared to the susceptible and relaxed lines (P#0.05). Ascites incidence was significantly higher in the susceptible and relaxed lines when compared to the resistant line; 18.8, 12.7, and 1.6 percent respectively (P#0.001). Susceptible and relaxed lines showed significantly more right ventricular hypertrophy when compared with the resistant line (P < 0.05). The results show that under severe cold stress at local altitude, the ascites resistant line was growing as rapidly as the other lines and was as resistant to ascites as they had been under hypobaric conditions.