A study has found that cows grow about 5cm faster than the population of humans over the course of a lifetime, but researchers warn that they’re likely to shrink in size in the future.
The findings, published in the journal Biology Letters, have not been confirmed by other studies.
However, they do suggest that there is a need for some intervention, including feeding calves the growth hormone IGF-1, which is normally given to humans.
This could help reduce the amount of milk they give away, as well as helping to increase their calves’ overall size.
“When we have this kind of growth in humans, the calves are actually bigger than we thought,” said Professor David Prentice, from the University of Queensland’s School of Animal Science.
“We think that’s due to the fact that they get this growth hormone from their mother, and that’s why they grow so fast.”
Cows are an important part of our ecosystem, he added.
“In the wild, cows produce milk for humans, and in Australia it’s the milk of our livestock.”
The study involved three groups of calves.
One group were raised in a large pasture with a herd of 20 cows and calves.
The second group of calves were housed in a larger pasture with three cows and three calves.
Cows have a large brain and are able to communicate with their mothers, who can recognise them by scent.
“Cows really do have a language,” Dr Prentice said.
“It’s really like a baby talking to its mother.”
The third group of cattle were housed at a dairy farm, where the cows were given injections of growth hormone.
“The cows had a lot more growth hormone in their milk, and the calves were more active and they grew faster,” Dr Rianne Smith, from Australia’s Department of Agriculture and Fisheries, said.
It is believed that the calves have a natural advantage in terms of size.
But the study also found that it is also possible that the increase in the cows’ milk was the result of the calves eating more of the milk than their mothers.
“They were eating more and more, so they had to be feeding more and less,” Dr Smith said.
In other words, the milk produced by cows is growing in proportion to the growth in the human body.
“So cows were growing much faster than humans were growing,” she said.
Dr Smith said that the findings could have a direct impact on the welfare of the cows, as it is possible that they may not be able to eat the milk they produce as much as they would like.
She said that even if the effect of growth hormones on cows is beneficial to humans, she believed the results of the study could have an impact on cows as well.
“You know if the cows are having problems with growth, you can feed them growth hormone, which has some other beneficial effects, and it can really help,” she added.
Dr Prentice explained that if the calves grew too big, they would lose milk from the cow, and there was a risk of starvation.
“And then the cows would have to get bigger and bigger to be able survive,” he said.
There is a possibility that the dairy industry might change its policy of not feeding cows IGF-like growth hormone injections, to instead give it to its animals as a natural supplement.