Bw. Woodward et al., DEVELOPMENT OF AN ANIMAL-MODEL FOR ACROSS-HERD GENETIC EVALUATION OF NUMBER BORN ALIVE IN SWINE, Journal of animal science, 71(8), 1993, pp. 2040-2046
An animal model and computer software were developed to conduct across
-herd genetic evaluations using data from producers participating in t
he Sow Productivity Index program of the American Yorkshire Club. The
final data set consisted of 61,596 litter records from 1986 to early 1
990. The animal model included fixed contemporary group effects and ra
ndom additive direct, service sire, permanent environmental, and resid
ual effects. Additive genetic relationships among animals were include
d. A separate relationship matrix for service sires and their sires wa
s also included. A data set similar to the Yorkshire field data was si
mulated to use in testing the animal model. The simulated data set con
sisted of 40 herds, each with 120 reproducing dams and either four or
five sires. Six generations of simulated data were produced, resulting
in 20,605 litter records. These records were then evaluated using the
animal model for number of pigs born alive. Finally, correlations bet
ween the true breeding values from the simulation and the predicted br
eeding values were computed. The correlation between the 918 true and
predicted sire breeding values was considerably lower for the animal m
odel without a service sire effect than when it was included (.53 vs .
74, respectively). However, the difference was cut in half (.66 vs .77
) when only sires with greater than five daughter records were include
d. The high accuracy of the animal model with a random service sire ef
fect indicates that the proposed model adequately accounts for the var
iation found in records for number of pigs born alive.