About 30 goats, more than 20 chickens, six cats, three dogs, three llamas — and that’s just a rough estimate.

To say Brian, Jodi and Riley Olsen like all things feathered and furry is an understatement. Their small hobby farm on 550th Street in Waltham is a Noah’s Ark of animals. A rooster crows repeatedly from atop a goat as two cats jump on a cage containing nearly 20 chickens that were born in an incubator. A brown llama named Chachi is tied up near a shed as his father and nemesis — a larger white llama — glares at him from across the yard. The two are separated because they would “fight to the death,” Jodi said.

The newest editions to the Olsen family came as a surprise — a big surprise, literally.

They knew one of their older goats, a Boer/Nubian cross named “Grandma,” was pregnant and due to give birth soon. On July 29, they came home to find the goat had her babies.

“We were like, one… two… three… four…” Brian recalled.

Grandma had five healthy female kids, although one must be bottle-fed.

“These are all females, so I’ll probably keep them,” Brian said.

Grandma had bred with a pygmy goat, he explained. The kids are a variety of colors, and bounce up and down in the stall as they fight for their turn to be fed. Riley, 6, cuddles with one of the kids, his favorite “because it’s nice and brown and it’s the first one born.”

Brian said he raises goats mostly for pets, but has sold them for meat. When he was a child, his father had cows and goats. After his father died, his mother sold the animals and they moved into town.

“Brian always wanted to get back out in the country, and when we bought the place in November of 2006, about the first thing he did was buy some goats,” Jodi said. “For the most part, they have just been pets, but someday we would like to be able to make some money from the animals.”

The Olsens are not sure what the likelihood is of a goat having five babies, but they know it is rare.

According to the National Pygmy Goat Association, pygmies are “precocious breeders, bearing one to four young every nine to 12 months after a five-month gestation period.”

However, the buck determines the gender and the doe determines how many will be born, said Annette Maze, livestock judge and manager of the United States Boer Goat Association.

She said two babies are typical for any breed of goat; five is very uncommon.

“It’s a rare occasion, but usually they don’t all live,” Maze said.

As of this week, the Olsens reported that Grandma and her babies — all five of them — are doing just fine.