The Jersey is the most efficient of the dairy breeds that produce milk in this country. The small brown cow, she has roots to the Island of Jersey.
Iowa is home to some of the country's leading Registered Jersey herds, including the top herd for Jersey Performance Index (JPI): the 355-cow herd owned by Trans-Ova Genetics of Sioux Center. The fully-genotyped herd has a herd average JPI of +68 after the April 2020 genetic evaluations.
The top milk and protein-producing Jersey herd in the nation hails from Iowa as well. The 185-cow dairy owned by John and Edwin Maxwell of Donahue has a 2019 lactation average (mature equivalent) of 26,768M, 1,014F and 1,254P. Actual production is 23,710M, 1,119F and 899P.
Doug Fairbanks, Anamosa, ranks sixth in the country for fat and 10th for protein, with an actual 2019 average of 20,737M, 1,129F and 767P on 54 cows.
Three other Iowa dairies also rank among the top 10 in the nation in categories based on herd size: Summit Farm Inc. of Lester, among herds with 150-299 cows; Trans-Ova Genetics, among herds with 40-79 cows; and Kaitlin Hanson of Decorah, among herds with 10-39 cows.
A Jersey matriarch from Iowa has also earned laurels in the 2019 Leading Living Lifetime Production Contest. Summetz Stephen Fence Fanny, Excellent-94%, owned by Summit Farm Inc., Lester, placed sixth for milk and protein and eighth for fat with 280,083M, 12,317F and 9,963P in 4,914 days.
Several other Jersey cows have placed well in show rings across the country. A few of the standouts are shown below.

Cinnamon Ridge Nitro Noble-ET
Very Good-87%
4-03 305 34,600 3.9% 1,360 3.6% 1,232
Nation's 4th high milk and fat records, 2019
Owned by Amy Maxwell, Cinnamon Ridge Jerseys, Donahue

Cinnamon Ridge Nitro Peppermint-ET
Very Good-87%
4-02 305 33,800 4.5% 1,529 3.6% 1,210
4,123 Cheese Yield
Nation's 5th high milk and 7th high protein and cheese yield records, 2019
Owned by Allison and Emily Maxwell, Cinnamon Ridge Jerseys, Donahue

Summetz Stephen Fence Fancy
Excellent-94%
Lifetime Production: 280,083M, 12,317F, 9,963P in 4,914 days
6th milk and protein, 8th fat, 2019 Leading Living Lifetime Production Contest
Owned by Summit Farm Inc., Lester

Lyon Ajack Bay
2018 All American Premier Performance Cow
2018 Reserve All American Senior Three-Year-Old
2017 Reserve All American Senior Two-Year-Old
Owned by Glamourview-Iager and Walton, Walkersville, MD
Bred by Lyon Jerseys, Toledo, IA

Schulte Bros Tequila Shot
Grand Champion, New York Spring Carousel, 2018
All-Canadian Senior Three-Year-Old, 2016
All-Canadian Four-Year-Old, 2017
Owned by Budjon Farms, Peter Vail and David Jordan, Lomira, WI
Bred by Schulte Brothers, Blairstown, IA

Schulte Bros Teq Euphoria-ET
2016 Reserve All American Junior Calf
Owned by Schulte Brothers, Blairstown, IA

Lyon Duke Dutchy
2013 Junior All American Aged Cow
Owned by Ben Sauder, Tremont, IL
Bred by Lyon Jerseys, Toledo, IA

Gadget Jade of Edgebrook
Overall Premier Performance Cow, All American Jersey Show and All American Junior Jersey Show, 2010
Owned by Tera Koebel, Three Oaks, MI
Bred by Patty Dilly, Montour, IA

Fredestel Laser P Nelly Bly
2010 Reserve Junior All American Aged Cow
Owned by Andy Sauder, Tremont, IL
Bred by Mark Metzger, Larchwood, IA