Williams R B
Coccidiosis Section, Pitman-Moore Europe, Harefield, Uxbridge, UK.
Vet Res Commun. 1994;18(3):189-98. doi: 10.1007/BF01839268.
A trial was carried out in 1-day-old broiler chicks raised for 54 days in floorpens under simulated commercial conditions, but isolated from all extraneous virulent coccidial infections, to demonstrate the safety of 'Paracox' attenuated vaccine administered at the recommended dose when chicks were 7 days old. The vaccine did not adversely affect the water consumption, faecal moisture or litter condition of the broilers. Recycling of the attenuated coccidia occurred in vaccinated birds, oocysts being present in the litter between 5 and 33 days after vaccination; a single peak of oocysts was detectable 5 or 12 days after vaccination. Unvaccinated medicated control birds did not produce oocysts, indicating freedom from both between-pen contamination by the vaccine and invasion of the chicken-house by extraneous coccidial infection. A small proportion (4%) of vaccinated birds had mild coccidial lesions when sampled at 26, 33 or 40 days after vaccination. Despite this, the vaccinated birds performed better than control (unvaccinated, nicarbazin-treated) birds and there was no post-vaccinal check in their weight gain. Their mean finishing weight was 10.4% greater, their food conversion ratio 7.2% lower and their mortality 44.4% lower than the unvaccinated control birds, reflecting the safety of 'Paracox' vaccine.
在模拟商业条件下于地面围栏中饲养54天的1日龄肉鸡雏鸡中进行了一项试验，但将其与所有外来的强毒虫球虫感染隔离开，以证明7日龄雏鸡按推荐剂量接种“Paracox”减毒疫苗的安全性。该疫苗对肉鸡的饮水量、粪便湿度或垫料状况没有不利影响。接种疫苗的鸡体内发生了减毒虫球虫的循环，接种疫苗后5至33天垫料中存在卵囊；接种疫苗后5天或12天可检测到卵囊的单个峰值。未接种疫苗的药物对照鸡未产生卵囊，表明既不存在疫苗在围栏间的污染，也不存在外来球虫感染侵入鸡舍的情况。一小部分（4%）接种疫苗的鸡在接种疫苗后26、33或40天采样时出现轻度球虫病变。尽管如此，接种疫苗的鸡比对照（未接种疫苗、用尼卡巴嗪处理）鸡表现更好，并且它们的体重增加没有受到疫苗接种后的影响。它们的平均出栏体重比未接种疫苗的对照鸡高10.4%，饲料转化率低7.2%，死亡率低44.4%，这反映了“Paracox”疫苗的安全性。
