An adaptation of the nonhuman animal observation section of the 2003 Swine
Welfare Assurance program (SWAP) was utilized to evaluate the behavior of
weaned pigs following vaccination with Ingelvac MycoFLEX® (Boehringer
Ingelheim Vetmedica, Inc., St. Joseph, MO) and Respisure®-One (Pfizer Animal
Health, Exton, PA). The objective was to determine if field observations of
markedly reduced pig activity following vaccination with certain Mycoplasma
hyopneumoniae vaccines could be confirmed and quantified by observing postvaccinal
pig behavior and feed disappearance. A total of 1,832 weaned pigs
17–23 days of age were allocated across 72 nursery pens (36 pens per treatment
group), resulting in approximately 25 pigs/pen with pen as the experimental
unit.
Pigs were evaluated to determine willingness to approach and feed disappearance
behavior pre- and postvaccination with each population of pigs serving as
its own prevaccination baseline for postvaccination behavior observations. After
entering and crouching down in a pen, the blinded observer counted all pigs who
approached him during a 15-s period. The pigs approaching the observer were
designated as willing to approach. The difference in pre- and postvaccination
values is reported here as a decrease in percentage approachability.
A significant decrease in postvaccination willingness to approach was observed
within both groups of pigs (p < .0001). However, the decrease in
willingness to approach was significantly less for the Ingelvac MycoFLEX®
vaccinated pigs compared with the Respisure-One vaccinated pigs (11.38% vs.
27.05%, p < .0001). The Ingelvac MycoFLEX® vaccinated pigs consumed
significantly more feed through 24 and 48 hr postvaccination (p < .0001 and
p D .0001, respectively). These findings suggest that willingness to approach and feed consumption may be useful parameters for assessing vaccine reactivity
(side effects) in pigs.