Evaluation of the efficacy of a trivalent vaccine mixture against a triple challenge with Mycoplasma hyopneumoniae, PCV2, and PRRSV and the efficacy comparison of the respective monovalent vaccines against a single challenge

Oh, Taehwan; Park, Kee Hwan; Yang, Siyeon; Jeong, Jiwoon; Kang, Ikjae; Park, Changhoon; Chae, Chanhee

The random number generator function (Excel, Microsoft Corporation, Redmond, Washington, USA) was used to randomly divide 130 piglets into 9 groups (Table 3) . A minimum sample size per each group was calculated as suggested by Cohen [24] using pwr package in R v.3.5.1 (R Core Team: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria, http://www.r-project.org). A 0.05 significance level, 0.4 effect size, and 70% power were used to calculate the minimum number of piglets needed per group. This value was determined as 9.47, therefore, at least 10 piglets were designated per group. Blinded personnel (defined as personnel who could not identify the vaccination status of the pigs) performed all actions including the administration of vaccines, administration of the PBS control, recorded observation and pulled defined measurements. The study was conducted at the Seoul National University, Department of Veterinary Pathology which contained a HEPA-filtered isolator. One room contained pigs from each group. The rooms each contained 10 pens with an individual pig housed per pen. Vaccinated groups were randomly assigned to each to include 20 pigs, 10 of which were female and 10 of which were male. These were further split into two rooms (10 pigs per room). Unvaccinated groups were assigned 10 pigs (5 male and 5 female) which were housed in a single room. The random number generator (Excel, Microsoft Corporation) was used to assign pigs to groups and rooms. Several key housing elements were taken into consideration such as both slatted and solid surface pen flooring, and rooms were lit for 12 h/day with the light intensity set to 40 lx in order to simulate daytime. The temperature in each room was also kept at a constant 22°C. Water was available for piglets to drink freely throughout the day via a nipple drinker which was placed in each pen. Each pen was additionally equipped with a self-feeder which provided access to a standard-balanced, age-appropriate, pelleted feed diet. Playtime stimulation was offered by placing a rubber ball in each pen.