He has also been disqualified from owning or exercising authority over farm animals indefinitely.
The Ministry for Primary Industries (MPI) found some of the cattle had "most likely entered swampy areas looking for food but were weak and became stuck in mud, eventually dying".
No evidence of supplementary feed being purchased, or plans for the sale of cattle, were found by inspectors.
A veterinarian concluded all 28 cattle would have died from multiple organ failure due to a lack of food and dehydration.
Wood was responsible for 232 cattle and 1400 sheep.
But an investigation on his farm in September 2020 found a "dire animal welfare situation", MPI said.
"These cattle were in terrible condition. They were weak and emaciated. There was no other option but to euthanise them to end their suffering," said Joanna Tuckwell, regional manager for animal welfare and National Animal Identification and Tracing (NAIT) compliance.
"These cattle suffered unreasonable and unnecessary distress due to starvation.
"Failing to have proper welfare plans in place and taking no action to help animals when aware they are suffering is unacceptable."
MPI animal welfare inspectors also found Wood had failed to meet the nutritional needs of 127 cattle and 600 sheep.
MPI said Wood told inspectors he had been aware of at least 15 animals dying as far back as July that year, which he put down to weather conditions and starvation.
MPI claims Wood also said he didn't have euthanasia procedures on the farm, or means to do so.
"Poor animal welfare behaviour can potentially affect the reputation of other farmers in the eyes of the public and in overseas markets," said Tuckwell.
"We strongly encourage anyone who is aware of possible animal ill-treatment or cruelty to report it to the MPI animal welfare complaints freephone 0800 00 83 33."