Sarah Lambert, 47, who runs a farm in Little Chaveldon Hall, Basildon, found 41 of the 70 cattle on the farm on the loose across the property.
Three heifers lost their calves due to the stress of the cruel attack.
Ms Lambert told the Basildon Echo: "It was a very horrifying weekend for us. From our CCTV footage there were about a dozen intruders carrying large lumps of wood with them. I think the attack was planned.
“They let the cattle out of their enclosure and tried to lure them into an electric fence. It was very disturbing watching them terrorise our livestock from our CCTV footage.
“Our oldest cattle are two years of age. We found one of the calves had a bell string tied very tightly around her neck.
The string was quite long so she could have tripped over it and strangled herself. Luckily she is OK now.
“None of our cattle were missing or dead, but three of our pregnant heifers lost their calves due to stress. It’s very sad for us because we’ve weaned those cows since they were little.”
Ms Lambert reported the yobs also burnt a ring feeder which was on the field.
She said: “It was just so dangerous because they could have burnt down the entire field.
This isn’t the first time this has happened to us.
“In summer this year we had yobs chasing down our cattle to the electric fence. We’ve had these problems in the past two years, we’ve had people breaking into our property and wrecking our fences. If anyone has seen or heard anything please contact the police.
"I want to make sure my staff members are safe."
An Essex Police spokesman said: “We’re investigating an incident, where items were thrown at cattle and a cattle ring feeder was set on fire.
“Anyone with information is asked to contact Basildon police station on 101. “Alternatively call Crimestoppers anonymously on 0800 555111.”