Department of Animal Science


Date of this Version

January 1981


Published in JOURNAL OF ANIMAL SCIENCE, Vol. 52, No. 1, 1981. Copyright American Society of Animal Science. Used by permission.


Estimates of direct and maternal genetic and heterosis effects for purebreds and crosses among the Duroc, Hampshire and Yorkshire breeds were made from data on 1,243 litters from the Oklahoma crossbreeding experiment. The estimates were used to simulate the production efficiency of 21 mating systems. Each mating system was defined to include purebred, crossbred and commercial matings needed to maintain 10,000 farrowings. Linear programming was used to maximize the number of Yorkshire equivalent pigs foreach system. An index of economic weights for days to 100 kg, feed efficiency and probe backfat (traits expressed as a deviation from Yorkshire) was calculated for each breed cross. The index was multiplied by the number of pigs weaned to give the number of Yorkshire equivalent pigs for each cross. The mating system in which market animals were produced by the back-crossing of Yorkshire males to F1 Duroc-Yorkshire (Y × DY) females produced the greatest number of Yorkshire equivalent pigs per 10,000 farrowings. The specific breed combination of Duroc males × Hampshire-Yorkshire females (D × HY) ranked the highest in production efficiency but when all matings needed to support the system were included, the number of Yorkshire equivalent pigs produced was 96.9% of the Y x DY system. The relative efficiency of various crossbreeding systems for number of index value pigs was: purebreds, 100; two-breed terminal crosses, 115; backcrosses, 122; two-breed rotations, 123;rotation female x terminal male, 124; three-breed rotation, 125; threebreed terminals, 127.