Balog J M, Kidd B D, Huff W E, Huff G R, Rath N C, Anthony N B
USDA/ARS/PP&PSR, Fayetteville, Arkansas 72701, USA.
Poult Sci. 2003 Sep;82(9):1383-7. doi: 10.1093/ps/82.9.1383.
Genetic selection for an ascites-resistant line of broilers is seen as a permanent solution to the ascites problem. Ascites-resistant and ascites-susceptible lines have been developed using sire family selection based on mortality data taken from siblings reared in a hypobaric chamber (simulated 2,900 m above sea level). The relaxed line is representative of the original commercial pureline stock randomly mated with no artificial selection pressure. The objectives of this study were to evaluate the differences between the lines when reared in floor pens and subjected to an ascites-inducing cold stress. Seven hundred eighty three straight run broilers were reared in floor pens at local elevation (390 m above sea level). Feed and water were available ad libitum. Birds were brooded at 32 C during the first week. The second week birds were maintained at 30 degrees C. Cold stress was applied for the remaining 4 wk at 14 degrees C. Mortalities were necropsied daily to determine cause of death. Birds and feed were weighed weekly. At 6 wk, five birds per pen were bled, and half the survivors in each pen (8 to 15 birds) were killed, necropsied, and scored for ascites. Blood gases, clinical chemistries, and blood cell counts were taken. Liver, spleen, split heart, and lung weights were recorded. Body weights were not different among the resistant, susceptible, and relaxed lines (P < 0.05). Feed conversion was better in the resistant line when compared to the susceptible and relaxed lines (P < 0.05). Ascites incidence, as measured by mortality and lesion score at necropsy, was higher in the susceptible and relaxed lines when compared to the resistant line; 18.8, 12.7, and 1.6% respectively (P < 0.001). Susceptible and relaxed lines showed more right ventricular hypertrophy when compared with the resistant line (P < 0.05). The results show that under severe cold stress at local altitude (390 m above sea level), the ascites-resistant line was growing as rapidly as the other lines and was as resistant to ascites as it had been under hypobaric conditions.
对肉鸡腹水抗性品系进行遗传选择被视为解决腹水问题的永久性方案。基于在低压舱（模拟海拔2900米）饲养的同胞的死亡率数据，利用父系家系选择法培育出了腹水抗性品系和腹水易感性品系。对照品系代表了原始商业纯系种群，随机交配，无人工选择压力。本研究的目的是评估在地面平养并遭受诱发腹水的冷应激时各品系之间的差异。783只初生雏肉鸡在当地海拔（海拔390米）的地面平养环境中饲养。自由采食和饮水。第一周雏鸡在32℃下育雏。第二周雏鸡维持在30℃。在接下来的4周内，将温度降至14℃施加冷应激。每天对死亡鸡只进行剖检以确定死因。每周对鸡只和饲料进行称重。在6周龄时，每个围栏选取5只鸡采血，每个围栏中一半的存活鸡只（8至15只）宰杀、剖检并对腹水进行评分。采集血气、临床化学指标和血细胞计数。记录肝脏、脾脏、半颗心脏和肺脏的重量。抗性品系、易感性品系和对照品系之间的体重无差异（P<0.05）。与易感性品系和对照品系相比，抗性品系的饲料转化率更好（P<0.05）。通过死亡率和剖检病变评分衡量的腹水发病率，易感性品系和对照品系高于抗性品系；分别为18.8%、12.7%和1.6%（P<0.001）。与抗性品系相比，易感性品系和对照品系表现出更明显的右心室肥大（P<0.05）。结果表明，在当地海拔（海拔390米）的严重冷应激条件下，腹水抗性品系的生长速度与其他品系一样快，并且对腹水的抗性与在低压条件下相同。
