Synlait Milk (NZE:SML, ASX:SM1) said it implemented enhanced testing earlier this year for all infant formula products, which resulted in extended release times and also had an impact on working capital requirements, according to a Monday filing with the New Zealand bourse.

The company issued the statement in response to a same-day disclosure from the a2 Milk Company (NZE:ATM, ASX:A2M), which said there is a backlog of unfilled purchase orders at the Synlait plants that produce infant milk formula.

Synlait said it has worked through the associated supply chain impacts with the support of the a2 Milk Company, adding that "production has recently returned to targeted levels."

Synlait said it has also been impacted by the supply chain issues noted in the a2 Milk Company's filing, including product release and clearance times, a shifting regulatory landscape, and a challenging geopolitical and trading environment.