Sygen - formerly known as The Pig Improvement Company - specialises in applying genetic techniques to animal breeding. It is listed on the London Stock Exchange, but based in Berkeley, California and operates mainly in the USA.
WMC chief executive Alex Glover said the company had been approached to take over the account - which was not subject to a pitch and was previously held by Hudson Sandler.
The work will principally involve investor relations in the UK and raising the company's corporate profile globally.
Although the company has traditionally specialised in pigs, it has recently begun applying its techniques to other livestock - in particular to shrimp farming.
Glover said the move into shrimp farming techniques was the biggest challenge facing the company. If its work in improving productivity at US shrimp farms is successful the firm could gain a foothold in a market worth close to £5bn a year.
The account will be handled by a three-strong team, headed by Glover.
WMC started work last week for the company with the announcement of its full year results.