Mark and Suellen Purden, of Te Aroha, had been found guilty by a jury in Hamilton District Court.

Suellen Purden, 28, unemployed, was also sentenced to nine months' jail, to be served cumulatively, for assaulting the baby boy who was eight-months-old at the time.

During sentencing yesterday, Judge Robert Wolff said neither parent had accepted responsibility for their actions.

The boy had suffered injuries to one hand and his skull, he said. At one stage the parents had left his care to another person but later changed their minds.

"You took a healthy and thriving child into your care and that child suffered at your hand," Judge Wolff told the couple.

"The child wasn't only physically malnourished but, because of the attitude you had towards the child, it was emotionally malnourished as well," he said.

Judge Wolff said the two favoured their older child over their younger one.

The couple's relationship was described by the judge as "co-dependent" with a "remarkable lack of communication".

He said the lack of communication was partially due to Mark Purden's deafness.

However, he told Purden, a 32-year-old farm manager, that his skills in animal husbandry and concern for small creatures should have alerted him to the child's suffering.

Evidence was presented to the court that Suellen Purden had shaken the child, which the judge said had the potential to cause significant permanent harm.

"No one is to know if his physical health and emotional health has not been scarred for life," Judge Wolff said.

Mark Purden was given leave to apply for home detention