http://www.ansci.wisc.edu/research/twin/index.html
i think maine's average about 6%. guy claims he has identified genes. even has twinning bull semen for sale. look at these twinning rates
USDA ID#928507, 26.8 twinning rate EBV (USDA), polled.
Owner: Dave Serfling.
Contact Dave Serfling at 507-765-2797.
USDA ID#888521, 47.9 twinning rate EBV (USDA),
Owner: Daren Cyphers.
Contact ABS Global Inc, 1 - 800 - ABS - STUD.
USDA ID#949673, 42.8 twinning rate EBV (USDA).
Owner: Daren Cyphers.
Contact Hoffman A.I. Breeders, 801 - 753 - 7883.
USDA ID #918521, 50.7 twinning rate EBV (USDA),
Owner: Sean Smith.
Contact Sean Smith, 1211 240th Avenue, Thurman, IA 51654. 712-628-3005.
USDA ID#969549, 55.9 twinning rate EBV (USDA).
Owner: Dave Serfling.
Contact Dave Serfling at 507-765-2797.
USDA ID#998628, 64.0 twinning rate EBV (USDA), progeny test not completed
Owner: ProlifiCow Inc.
Contact Brian Kirkpatrick, 5615 Longford Terrace, Madison, WI 53711, 608-271-6904.
USDA ID#969381, 67.3 twinning rate EBV (USDA),
Owner: ProlifiCow Inc.
Contact Brian Kirkpatrick, 5615 Longford Terrace, Madison, WI 53711, 608-271-6904.