Artificial Insemination: The Breeding Tool That Let One Bull Sire Thousands

What Is Artificial Insemination in Cattle?

Artificial insemination, usually shortened to AI, means collecting semen from a bull and placing it in a cow or heifer by hand instead of by natural service. The idea is simple. The consequences are not, because it separates a bull's genetics from the bull's body. One animal can father calves on many ranches, in several states, and long after he has died.

Semen is collected by artificial vagina, which sources describe as the preferred method, or by electro-ejaculator or manual massage. It is then extended, cooled or frozen, and delivered to the cow by a trained technician or by the producer. For beef cattle, the appeal is concentrated in the bull battery: choose the best sire you can find, and use him across the whole herd.

The 1938 New Jersey Cooperative That Started It in America

The American story has a precise starting point. According to a Rutgers account of Enos J. Perry's career, Perry reported in 1937 on a breeding cooperative he had seen in Denmark, and he presented the idea to the Hunterdon County Board of Agriculture. An organizational meeting followed at the county courthouse in Flemington on March 28, 1938.

The group became the Cooperative Artificial Breeding Association, Unit #1, covering Hunterdon, Somerset and Warren counties. The Rutgers piece counts 45 dairymen paying a $5 enrollment fee, while the Wikipedia article on frozen bovine semen gives 102 members and 1,050 cows enrolled and a start date of May 17. Sources differ on these details, but both agree the first American cattle AI cooperative began in New Jersey in May 1938.

The Rutgers account says the first breedings took place on May 16, 1938, on four farms, and that the first calf born by AI in the United States arrived in February 1939 at the Schomp Farm in Stanton. Bulls were housed at a farm in Belle Mead, and early breedings were handled by a Danish inseminator, Falmer Larsen, and a veterinarian, J.A. Henderson. New Jersey's cooperatives preceded New York's by about two months.

Frozen Semen: The Change That Made AI Global

Early AI depended on fresh semen. Before freezing, semen was extended, kept cool and delivered to technicians, usually daily, which limited AI to areas near a bull stud. Frozen semen has been used in dairy cattle since the 1950s, and the Wikipedia article on frozen bovine semen credits Christopher Polge with discovering the freezing process, with glycerol added to the extender.

Packaging changed too. Semen was first frozen in sealed glass ampules kept in dry ice and alcohol. Liquid nitrogen refrigerators, developed by Union Carbide with funding from John Rockefeller Prentice, were later given to the AI industry without charge or royalty, according to that article. Plastic straws, invented in the 1960s by the Cassou family business IMV in France, became the common format, and automatic filling and printing equipment is now standard in bull semen laboratories.

The oldest semen believed to still exist came from the sire Cottonade Emmet, collected in November 1952 in the American Breeders Service battery. The last offspring from it were born in the mid-1980s, which shows how long frozen genetics can wait.

How Beef Producers Use AI

Dairy adopted AI first and fastest. By the time of the 2014 Rutgers article, roughly 80 percent of U.S. dairy cows were bred by AI. The sources reviewed give no comparable figure for beef, so this entry makes no claim about beef adoption rates. The technique is well suited to the herd improvement that beef breed associations promote.

A beef bull may naturally service only 20 to 30 cows in a breeding season, according to the frozen semen article. Through AI he can serve many more, and even if he is injured, disabled or dies, stored semen can still sire hundreds or thousands of calves. Many beef bulls are collected at stud, while others are collected on farms or at custom studs.

The Man Behind the Idea: Enos J. Perry

Enos J. Perry lived from 1891 to 1983 and worked for Rutgers as an extension specialist in dairy husbandry from 1923 to 1956. His 1945 book became a standard reference, and he was inducted into the National Agricultural Hall of Fame in 1984, one of 39 members at the time and one of two from New Jersey, according to Rutgers. His work shows how extension agents, not only breeders, moved livestock science onto working farms.

Where to Read More

A trade-press overview, such as this history of artificial insemination from a farm magazine, offers a readable starting point. For stories from working ranches that use bull genetics, see the ranching section of farm.FM, or read a farm.FM story about breeding bulls.