Breed-specific weight adjustments
for growth, backfat and loin muscle depth
Everestus Akanno, PhD, Geneticist, Genesus Inc.
Selection of parents of the next generation of pigs in nucleus breeding programs requires accurate estimation of breeding values for several traits. Among the traits evaluated in a typical swine genetic improvement scheme includes body weight and real time ultrasound backfat and loin depths measured at a given target weight or age.
These traits are collected through performance recording of individual pigs over a wide range of weights and ages. Consequently, adjustment factors are developed to standardized performance information before they are used in genetic evaluation (Moeller et al., 1998, J. Anim. Sci. 76(8):2008-16).
The assumption is that fat accretion and growth rate are linear within a short growth period and differ among pigs, thus, adjusting these performance records will account for differences in growth pattern (Yun Ho Choy et al., 2015, Asian-Australas J. Anim. Sci. 2015 Dec; 28(12): 1696–1702).
Additionally, adjustment factors should be calibrated for different gender and breeds and be reviewed periodically to account for changes in population structure as a result of genetic selection overtime.
At Genesus Inc., individual pigs are performance tested to about 80 kg and 120 kg weight targets. These weight targets represent growth rate from birth after converting to days required to reach 80 kg and 120 kg body weights and are used to adjust ultrasound backfat and loin depths.