"This is the worst and I have seen some awful cases. It is for that reason that we are telling you we believe this has passed the custody threshold."
Prosecuting for the RSPCA, Lindi Meyer told the court that the abuse came to light after Animal Equality placed a covert camera in a barn.
The footage, recorded between 9am and 9.30am on December 8 last year, was later passed to the RSPCA.
"The footage shows acts of violence against the cows and calves," Ms Meyer said.
"He [Nichols] is continuously swearing at the cows. He gives a heavy kick to one of the new mothers.
"He kicks her full in the face and throws her newborn calf away from her.
"He kicks and stamps on one calf seven times. The violence was unprovoked and totally unnecessary."
Ms Meyer said the calves in the footage ranged between newborn and two days old.
In a report for the RSPCA, a vet said the cows would have suffered "considerable pain and distress" from Nichol's abuse.
He described the case as "the worst example of abusive behaviour" he had seen in a 35-year career.
Nichols was working at the farm for a year as part of his apprenticeship, the court heard.
In interviews, he told officers the violence was not related to the cows and calves, adding: "I just flipped".
He said his grandmother had been in hospital with pneumonia and he had separated from his girlfriend months earlier.
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 court heard Nichol was dismissed from the farm when the footage was released. He has no previous convictions.
Speaking outside court, RSPCA Inspector John Pollock described the abuse as "horrible and appalling".
He added: "It is no reflection on the farm. The farm has probably the highest welfare standards I have seen."
Dr Toni Shephard, executive director of Animal Equality UK, described Nichol's actions as "unthinkable cruelty".
She added: "We are pleased that he has been convicted for this terrible violence against dairy cows and young calves and we hope that he will receive the harshest sentence possible."
Nichol will be sentenced at Taunton Magistrates Court on April 26.