Characterization of Hereford and Two-Breed Rotational Crosses of Hereford With Angus and Simmental Cattle: Carcass Traits of Steers

Calf carcass traits were evaluated for Simmental (S) x Hereford (H) and Angus (A) x H cross cows in two-breed rotations and for straightbred H. Data were grouped into seven dam breed categories: straightbred Hereford (H), F1 S x H cows (SH), S x H cows of low percentage H (SHS), S x H cows of high percentage H (HSH), F1 A x H cows (AH), A x H cows of low percentage H (AHA) and A x H cows of high percentage H (HAH). Straightbred H and crossbred SH, AH, SHS and AHA cows were mated to H bulls, HSH cows were mated to S bulls and HAH cows were mated to A bulls. Calves from S x H dams produced heavier carcasses with less fat, lower quality grade, larger longissimus area and increased estimated cutability compared to calves from H or A x H dams. Some significant intergenerational differences were observed within rotations, particularly within S x H. Calves from HSH cows mated to S bulls produced carcasses with less fat cover, lower quality grade, larger longissimus muscle area and higher estimated cutability compared to calves from SHS dams mated to H bulls. Within both rotations, evaluation of carcass weight per day of age indicated lower postweaning rate of gain for generations in which H was the sire breed. A separate analysis evaluated carcass traits of calves from SHS, HSH, AHA and HAH dam breed groups from the last 3 years of the study when calves were fed under two different postweaning management systems. With Management System One, the concentrate to roughage ratio was increased less rapidly and calves averaged 122 days older at slaughter and carcass weights averaged 128 Ib heavier compared to calves fed under Management System Two. The breed group x postweaning management system interaction effect approached significance only for marbling score, estimated cutability and kidney, pelvic and heart fat