Animal rights activists have criticised a decision not to jail a farm apprentice who was secretly filmed hitting, stamping on and throwing newborn calves at a Somerset farm.

Owen Nichol, 18, who attacked the calves and a cow and repeatedly swore at the animals, was given a suspended prison sentence.

He was caught on film by the organisation Animal Equality after it received a tip-off from a neighbour about what was happening at Pyrland Farm in Taunton.

During a four-minute clip, Nichol is seen kicking a cow who had just given birth, slapping her and slamming a gate on her. He throws her calf six times, kicks its body and face and slaps it. Nichol then kicks and stamps on another calf seven times.

Nichol, who was dismissed from his job as soon as the footage was released, told RSPCA investigators: “I just flipped.”

The teenager admitted two charges of causing unnecessary suffering to the animals contrary to the Animal Welfare Act 2006.

Peter Reed, the chair of the bench at Taunton magistrates, sentenced Nichol to 12 weeks in prison suspended for one year, and 150 hours of unpaid work.

“Your behaviour in the incident was absolutely unacceptable,” Reed told Nichol. “The offence was deliberate, it was sustained.”

Reed said the offences passed the custody threshold but Nichol would be given a suspended sentence because of his age, lack of previous convictions and circumstances at the time of the incident.

“You were working under pressure, you were working beyond your capabilities,” Reed said. Nichol was also disqualified from owning, keeping and participating in keeping animals for two years.

A still from a video showing Nichol kicking a cow that had just given birth. Photograph: Animal Equality/PA

Dr Toni Shephard, Animal Equality’s UK director, expressed concern at the sentence. He said: “We are extremely disappointed that this dairy farm worker has not been sent to prison for the disgusting attacks on vulnerable cows and calves revealed by our investigation. Anything less than a custodial sentence is a wholly inadequate punishment for these disturbing acts of cruelty.

“This case highlights the dangerous lack of oversight and complete absence of independent, unannounced inspections which leave all farmed animals at risk of abuse and suffering. Without our investigation, this worker would still be beating those poor animals today.”

In a report for the RSPCA, Andrew Biggs, a past president of the British Cattle Veterinary Association, said: “This is the worst example of abusive behaviour I have seen in the 35 years I have been a veterinary surgeon.”

At the time of the filming, Nichol had been working at the farm for a year. He told officers his grandmother had been in hospital and he had separated from his girlfriend.

Nichol, who has a flock of sheep, said he had “very little sleep” as he had been working for his father as well as nights at the farm.

The farm has undergone a number of inspections since the incident and staff have received training, the court heard.

In mitigation, Martin Winter said Nichol had been working alone and unsupervised. Nichol now plans to work on an arable farm, the court heard.