Nielsen Gitte Blach, Nielsen Jens Peter, Haugegaard John, Denwood Matthew J, Houe Hans
Department of Large Animal Sciences, University of Copenhagen, Grønnegårdsvej 2+8, 1870 Frederiksberg C, Denmark; MSD Animal Health Nordic, Havneholmen 25, 1561 Copenhagen V, Denmark.
Department of Large Animal Sciences, University of Copenhagen, Grønnegårdsvej 2+8, 1870 Frederiksberg C, Denmark.
Prev Vet Med. 2017 Jun 1;141:14-21. doi: 10.1016/j.prevetmed.2017.04.003. Epub 2017 Apr 15.
During the last decade, the clinical manifestation of Porcine Circovirus type 2 (PCV2) infections has mostly changed from postweaning multisystemic wasting syndrome and high mortality to sub-clinical infections manifested only through impaired production parameters. However, co-infection with other respiratory pathogens often results in a larger effect on production, sometimes with clinical signs. Little is known about the impact of a moderate level PCV2 infection without co-infections, particularly in terms of feed conversion ratio and antimicrobial consumption. The purpose of the study was to evaluate the effect of vaccination against PCV2 in a sub-clinically infected, high-health finishing herd in terms of viral load in serum, feed conversion ratio and antimicrobial treatments. The study was conducted as a randomised clinical field trial with a parallel group design. Vaccination against PCV2 significantly (p<0.001) reduced the prevalence of PCV2-positive serum pools, from 91% in the control group to 6% in the vaccinated group, as well as the viral load for positive pools from 5.79 to 3.99 log(10) copies per ml serum. Despite this, feed conversion ratio for the two groups were not significantly different with an average of 2.75 and 2.76 feeding units/kg gain for vaccinated and control pigs, respectively (p=0.598). The proportion of pigs treated by injection with an antimicrobial was lower in the vaccinated group (4.4%) compared to the non-vaccinated group (5.6%), but the difference was not significant (p=0.125). In conclusion, in this herd without respiratory co-infections and with moderate viral loads of PCV2, vaccination significantly reduced the prevalence and viral load of PCV2-positive pigs, but had no significant impact on feed conversion ratio or antimicrobial consumption.
在过去十年中，猪圆环病毒2型（PCV2）感染的临床表现大多已从断奶后多系统消耗综合征和高死亡率转变为仅通过生产参数受损表现出的亚临床感染。然而，与其他呼吸道病原体的共同感染通常会对生产产生更大影响，有时还会出现临床症状。对于无共同感染的中度PCV2感染的影响，尤其是在饲料转化率和抗菌药物使用方面，人们了解甚少。本研究的目的是评估在一个亚临床感染、高健康水平的育肥猪群中，针对PCV2进行疫苗接种对血清病毒载量、饲料转化率和抗菌药物治疗的影响。该研究作为一项随机临床现场试验，采用平行组设计。针对PCV2的疫苗接种显著（p<0.001）降低了PCV2阳性血清池的患病率，从对照组的91%降至疫苗接种组的6%，同时阳性血清池的病毒载量从每毫升血清5.79 log(10)拷贝降至3.99 log(10)拷贝。尽管如此，两组的饲料转化率没有显著差异，疫苗接种组和对照组的猪每增重1千克的平均饲喂单位分别为2.75和2.76（p=0.598）。与未接种疫苗的组（5.6%）相比，接种疫苗组中通过注射抗菌药物治疗的猪的比例较低（4.4%），但差异不显著（p=0.125）。总之，在这个没有呼吸道共同感染且PCV2病毒载量适中 的猪群中，疫苗接种显著降低了PCV2阳性猪的患病率和病毒载量，但对饲料转化率或抗菌药物使用没有显著影响。
