MPI acting director of compliance Steve Gilbert said the Ministry takes animal abuse very seriously.
"The mistreatment of animals will not be tolerated. When we get information about the mistreatment of animals, we investigate. When there is offending, people are held to account."
MPI laid a further four representative charges against a company and an individual last month in relation to alleged animal welfare offences involving bobby calves.
The first hearing for those charges has been set down for June 21.
MPI recently consulted on new bobby calf regulations as part of a wider animal welfare regulations consultation process.
Mr Gilbert said once the bobby calf regulations were implemented MPI would work with farming, transport, vet and processing groups to ensure everyone was informed and made aware of the new rules.
"We will work with all interested parties to support their introduction".
The footage which uncovered the abuse was collected by Farmwatch New Zealand, which welcomed the guilty plea.
John Darroch, who helped obtain the footage, said it vindicated the use of hidden cameras by Farmwatch.
"However it is unfortunate that New Zealand is having to rely on a voluntary organisation in order to bring animal abuse to light. Our hidden camera investigation uncovered animal abuse at every stage in these calves' lives.
"Because MPI does not engage in any surveillance like ours the public can have no confidence that such abuse of calves is not currently occurring."
Mr Darroch called on MPI to follow Farmwatch's lead and begin carrying out pro-active investigations.
Meanwhile, Erickson will be sentenced on July 28.
The penalties for the offences range from a maximum penalty of five years imprisonment or maximum fine of $100,000 or both, to charges carrying a maximum penalty of 12 months imprisonment or a maximum fine of $50,000 or both.