Warning: Graphic Content.

A former Westport dairy manager who shot a cow in the leg and dumped another live cow in an offal pit after breaking the tails of hundreds of others, was convicted in the Greymouth District Court today on a raft of charges of wilful and reckless animal cruelty.

Michael James Whitelock pleaded guilty to three charges each of wilfully ill treating an animal, and one of reckless ill treatment.

Whitelock also offered guilty pleas to one charge of unlawful possession of a firearm, two of possessing a firearm without a licence, one of possession of explosives and another of attempting to pervert the course of justice.

Judge Stephen O'Driscoll convicted Whitelock on all charges.

While a dairy unit manager at the Landcorp Totara dairy farm at Cape Foulwind, Whitelock broke the tails of 152 cows and 57 heifers, and subsequently failed to provide adequate treatment for their injuries.

Whitelock and three other farm employees - Cameron George Intemann Hurst, Hayden Lee Flintoff and James Anthony Murphy - shot one cow in the leg, while Whitelock and Hurst beat another cow. Hurst, Flintoff and Murphy have previously been sentenced in Christchurch.

Whitelock also shot another cow in an attempt to try to euthanise it, and then dumped it in the offal pit without making sure the cow was dead. He also made an injured cow walk 2km to the offal pit while it had a broken hoof, and made another's cow udder bleed after beating it.

Whitelock and Hurst were also both heard shouting the phrase, "this is Totara b...h", while violently attacking the cows.

Whitelock had a shotgun, a .243 and a .22 rifle, for which he had no licences, alongside .243 ammunition, which were found stashed in his children's bedroom in Timaru. He was also charged with trying to persuade a witness to give a false statement to investigators.

Whitelock had been employed by Landcorp in July 2012. He was sacked in September 2013, at the same time as senior management at the farm were made aware of a large number of cows suffering from broken tails, something verified by a veterinary inspection of the herd.

An internal investigation by the farm uncovered a number of "serious animal welfare issues", which were reported to the Ministry for Primary Industries and Landcorp management.

In the same month MPI began to investigate the case, and, alongside the host of animal welfare issues, investigators uncovered phone and text messages which showed that Whitelock had tried to cover up the firearms he possessed and the abuse which had taken place at the farm.

An assault on a cow with a fencing baton left the animal with a "traumatic injury to the eye". Whitelock then tried to kill the cow, but failed and ended up putting it into the offal pit while it was still alive.

Prior to a cow being euthanised, it was shot in the leg by Flintoff, under orders from Whitelock. Meanwhile, Whitelock, Murphy, and Hurst each shot the cow in its other legs.

Another animal was chased, pulled to the ground by the tail and punched and kicked. After the attack Whitelock said that he "loved the time of the year" when he "got to beat the cows".

He also swept the legs away on an animal while it was on the milking platform, something which was apparently done in a "fit of temper" when the cow repeatedly kicked off the milking cups. Another animal that did the same thing was beaten on the legs with a bar with such force that the bar smashed in his hands.

Fellow defendant Toni Lee-Pottle had two charges of attempting to pervert the course of justice and one of unlawfully possessing explosives withdrawn.

Whitelock was remanded on bail to be sentenced on October 7.