Bull-half sib steer comparisons: phenotypic correlation and carcass prediction using ultrasound

Abstract

Records from Angus bulls (n = 257) and steers from Angus sires (n = 212) over a four-year period were used in this analysis. The bulls and steers shared in common twenty Angus sires. All animals were serially scanned from weaning to slaughter for the following ultrasound traits: 12th_13th rib fat thickness (FTK), ribeye area (REA), rump fat thickness (RF), percentage intramuscular fat (PFAT), and weight at scanning (WT). Phenotypic correlation estimates between bull data adjusted to a year of age and steer data adjusted to average age at slaughter (390 days) were derived by the CORR procedure from SAS and were correlated by sire. Two sets of correlation estimates were derived, no age of dam adjustments in either sex and bull data adjusted using pooled estimates from the American Angus Association (AAA). The more notable estimates are as follows (AAA adjustments). 19, -. 41, .19, .42, .40, -. 43 for SREA (steer REA) and BREA (bull REA), SREA and BFTK, SFTK and BFTK, SPFAT and BFTK, SPFAT and BPFAT, SREA and BRF, respectively. Prediction models were derived using bull measures adjusted to a year of age and for age of dam (AAA) to explain steer marbling score (MS) and percent retail product (PRP). All explanatory and response variables were averaged by sire. The final prediction model for PRP explained 47.5% of the variation and included BFTK, BRF, BPFAT and the interaction between BFTK and BPFAT. The final prediction model for MS explained 34.2% of the variation and included BRF, BPFAT, the interaction between BRF and BFTK, and the interaction between BPF AT and BFTK.

Assessment of the breeding value of Holstein black-and-white stud bulls in the Republic of Kazakhstan

“…Currently, in the practice of breeding work with dairy cattle of the agro-industrial complex of Kazakhstan, the verification of dairy bulls for the quality of offspring is carried out according to the Instructions officially approved by the scientific and technical council of the Ministry of Agriculture of the Republic of Kazakhstan (Babich et al, 2019;Abugaliyev et al, 2021). This normative legal act involves the comparison of phenotypic indicators of the offspring of the tested bulls with the corresponding indicators of their peers on the basis of the "daughter-peers" principle (Bourdon & Brinks, 1986;Spangler, 2003). In each household, the peers of the daughters of the tested bull are descendants of other studs; however, the dates of birth and age of the first calving of daughters and peers should not exceed six months.…”