McDougald L R, McQuistion T E
Avian Dis. 1978 Oct-Dec;22(4):765-70.
Turkeys 2, 6, or 10 weeks old that had been reared free of coccidial infection were susceptibe to infection with Eimeria meleagrimitis, E. adenoeides, and E. gallopavonis. The 6- or 10-week-old birds were more resistant to infection than the 2-week-old birds (no deaths from coccidiosis vs. 100% mortality). Lesion scores were lower in 10-week-old birds than in 6-week-old birds, but significantly greater weight losses occurred in the older birds. Turkeys reared in floor pens contaminated experimentally with coccidia were immune to homologous challenge at 10 weeks old, with only slight (numerical) reduction of weight gains following challenge with 50,000 oocysts/bird of each species. These results demonstrated some degree of innate resistance associated with age, although not enough to protect against heavy challenge. The resistance of birds reared in floor pens was due largely to acquired immunity resulting from infection with coccidia. Amprolium (125 ppm), monensin (100 ppm), or Polystat (250 ppm) protected the turkeys against experimental infections in floor pens, as measured by weight gains, feed efficiency, death due to coccidiosis, and lesion scores.
未感染球虫的2周龄、6周龄或10周龄火鸡对感染火鸡艾美耳球虫、腺状艾美耳球虫和火鸡孔雀艾美耳球虫敏感。6周龄或10周龄的鸡比2周龄的鸡对感染更具抵抗力（球虫病无死亡 vs. 100%死亡率）。10周龄鸡的病变评分低于6周龄鸡，但老龄鸡的体重损失显著更大。在实验性感染球虫的地面围栏中饲养的火鸡在10周龄时对同源攻击具有免疫力，用每种球虫50,000个卵囊/只鸡攻击后，体重增加仅有轻微（数值上）降低。这些结果表明与年龄相关的一定程度的先天抵抗力，尽管不足以抵御严重攻击。在地面围栏中饲养的鸡的抵抗力很大程度上归因于感染球虫产生的获得性免疫。氨丙啉（125 ppm）、莫能菌素（100 ppm）或Polystat（250 ppm）可保护火鸡免受地面围栏中的实验性感染，通过体重增加、饲料效率、球虫病死亡和病变评分来衡量。
