H. Y. Chung, M. E.
Davis1, and H. C. Hines
The Ohio State University Department of Animal Sciences
Abstract
Effects of calpain genotypes on growth and insulin-like growth factor-I (IGF-I) concentration were examined in 233 purebred Angus calves divergently selected for blood serum IGF-I concentration at the Eastern Ohio Resource Development Center (EORDC). Genotyping was performed by polymerase chain reaction - single strand conformation polymorphism (PCR-SSCP) and restriction fragment length polymorphism (RFLP) analysis of the calpain and calpastatin loci. The PCR primers were selected from the calpain II regulatory subunit (CAPN4L4) and calpastatin domain I (CAST1). The IGF-I concentration on d 28 (IGF28), 42 (IGF42), and 56 (IGF56) of the 140-d postweaning test was determined. Birth weight (BW), weaning weight (WW), on-test weight (ONW), weight on day 28 (W28), 42 (W42), and 56 (W56) of the postweaning test, and off-test weight (OFW) were also measured. Fixed effects in this analysis were genotypes, year of birth (1995 and 1996), season (spring and fall), IGF-I selection line (high and low), sex of calf (bull or heifer), age of dam, and a covariate for age of calf. Genetic polymorphisms among individuals were observed for both loci (AA, AB, and BB). Differences in CAPN4L4 genotypes were found (P = 0.01) for WW, and CAST1 genotypes influenced ONW (P = 0.01), W28 (P = 0.09), W42 (P = 0.06), W56 (P = 0.03), and IGF56 (P = 0.05). Genetic variants discovered in this study may provide useful information for future selection programs.