The organisation said the decision had been made after the FSA had refused another offer to try to settle the dispute through independent conciliation.
The union said it had repeatedly called on the FSA to settle the dispute via conciliation service ACAS, and had put forward a range of proposals to allow talks to continue.
Unison is in dispute with the FSA following its decision not to pass on a 1% cost of living pay rise to its staff. Instead, a 0.75% rise was imposed, while the remainder was distributed to a selective part of the workforce.
‘Refused to budge’
"We have worked hard and done everything possible to avoid this dispute, right up to the eleventh hour,” said Unison general secretary Dave Prentis. “But we've been left with no choice because the FSA has imposed a settlement and refused to budge.
“Our members are not asking for a massive pay increase, just for the cost of living rise they are entitled to. This money should be distributed fairly and transparently to the entire workforce but the FSA has consistently refused to do this.
“This is not an attack on the meat industry or slaughterhouses. This is an issue with the FSA, which is why we've chosen to take two four-hour strikes at the beginning of the day in order not to undermine the industry.
“The strike is purely about stopping the FSA pick-pocketing our members, who work in some of the most dirty, difficult and stressful conditions to keep the public safe from contaminated meat.”
Meat inspectors, official vets and support staff in England, Wales and Scotland aim to stage two four-hour walkouts, from 6:30am to 10:30am on August 26 and again on August 27.
The decision to strike follows a ballot earlier this month, which saw Unison’s FSA members overwhelmingly vote for strike action over the imposed pay offer.
Unison claims to represent more than 500 meat inspectors, official vets and support staff employed by the FSA.