PSII-8 Analysis of maternal influence on phenotypic ultrasound measurements of weaned Angus calves

Abstract

Abstract Ultrasound carcass data can be used to accurately estimate the body composition of beef cattle in comparison with a body composition score. Literature regarding the analysis of phenotypic carcass data has focused predominately on yearling or mature cattle with limited measurements on weaned calves. Therefore, the influence of the milking ability of the dam on body composition traits measured via carcass ultrasound is unknown. The objective of this study was to estimate correlations between the maternal influence of the dam on the phenotypic ultrasound measurements of the calf. To quantify maternal influence, the expected progeny difference (EPD) for milk (MILK) of the dam was correlated to three ultrasound measurements of the calf: backfat thickness (BFAT), ribeye area (REA), and intramuscular fat (IMF). Ultrasound measurements were collected 1 wk after weaning on 104 purebred Angus heifer calves from the Iowa State University McNay Memorial Research and Demonstration Farm located outside Chariton, Iowa. The average age and body weight for heifers were 187 d and 195 kg, respectively. The milk EPD of the dam was correlated to the ultrasound measurements taken on the calves. For each trait, Pearson’s correlations were calculated between the ultrasound traits of the calf to the dam’s milk EPD using R Statistical Software version 4.3.1. A small positive correlation was identified between MILK and REA (r = 0.28, P = 0.004). This suggests a weak phenotypic relationship between MILK and REA for weaned heifers. The correlation between MILK to BFAT and IMF was 0.10 (P = 0.318) and -0.05 (P = 0.619), respectively. These correlations were not significantly different from zero. This suggests the potential for milk production of the dam has little association with BFAT and IMF for weaned heifers. Although further research is needed, the results from this study indicate little to no relationship between milk EPD of the dam on ultrasound measures of the calf for BFAT, REA, and IMF.