It's commonly understood that cows are getting bigger. When one considers that the cow population in the U.S. has shrunk since 1974, while total pounds of beef produced annually has been maintained at nearly 50 billion lbs. over the same time period, it is obvious that cattle have had to steadily increase growth potential and size.
Perhaps the more important question for a cow-calf producer is how big is the modern cow? More particularly, each producer might wonder how big their cows are. If everyone had a scale on the ranch, this would be known. The best alternative on a ranch-specific basis is to look at sale weights of cull cows and then try to adjust for any differences between the culls and the cows that remain in the herd.
In place of thinking specifically of each ranch, let's look at indicators of cow size in general. One indicator is the shift in expected progeny differences (EPD) genetic trends for cattle weights. For example, the genetic trend through time for the Angus breed has displayed a steady increase in weaning, yearling and mature cow weights. In particular, yearling weight, which is considered a reliable indicator of mature weight, has increased by 96 lbs. since the mid-1970s. We can expect that an increasing trend has occurred in other breeds as well.
To read the entire article, link here .