What Makes That Steer So Big? Cattle’s Mysterious Genes

What Makes That Steer So Big? Cattle’s Mysterious Genes


Once upon a time, everyone hoped that the internet, instead of becoming a bottomless pit of iniquity, would be filled with good and interesting information about large cattle.

And lo, it is.

But the viral photos of Knickers, the very large Australian steer, perhaps the largest steer around, have raised more questions than a leak from the Mueller investigation. The main one being, how did he get to be 6 foot 4 inches at the shoulder, and weigh about 3,000 pounds, so big that he escaped the abattoir. The answer seems to be if you’re a good-sized Holstein steer and you live long enough, you too could be a contender.

They are the Ben and Jerry cows, black and white. They are bred to produce milk. The breed is 2,000 years old and originated in Europe. They are also raised for their meat, and, since Knickers was a steer (a castrated bull), he unfortunately had no future in the dairy business.

It depends on the breed. According to Daren M. Sheffield, production records specialist at the Holstein Association USA, the average Holstein cow is about 4 feet, 10 inches tall at the shoulder and weighs about 1,500 pounds. Steers are usually slaughtered around 15 months at a weight of 1,300 to 1,400 pounds. It is rare for a steer to reach seven years of age.

But, Mr. Sheffield said, “Steers can grow to tremendous sizes at a mature age. It was not uncommon for Holstein cattle raised as oxen to reach weights of 3,000 pounds.” Oxen are steers raised for work like plowing.

Mr. Sheffield said the averages for Holstein bulls are less well known, but they do reach 6 feet and weigh up to 2500 pounds. “Mature steers such as Knickers can reach heavier weights than the average bull,” he said.

Bulls of other breeds can grow a lot bigger, though. A few years ago, Britain’s biggest bull, of a different breed, was 7 feet tall and weighed 4,000 pounds.

Genes contribute to size, but exactly which genes and how is not clear. In humans, there are many genes and genomic regions involved in determining height. In dogs, a few regions predominate.

An analysis earlier this year of cattle genomes concluded that cattle are more like humans than dogs. The researchers looked at genetic data from almost 60,000 cattle and found 163 gene variants contributing to height. All those gene areas accounted for less than 14 percent of height variation. Other contributors to size are food, environment and age.



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