| dc.description.abstract | The goal of this study was to assess the correspondence between feed efficiency and maternal traits, feed efficiency and carcass traits, and carcass traits and maternal traits. Two sets of data from Beefmaster Breeders United (BBU) were used. Efficiency traits included residual feed intake (RFI), average daily gain (ADG), dry matter intake (DMI) and gain to feed ratio (G:F). Ultrasound carcass traits included longissimus area (LA), intramuscular fat (IMF), and rib fat. Maternal traits included age at first calving (AFC), calving interval (CI), and disposal age. The first set of data included females that had been tested for feed efficiency (n = 277). The second set had ultrasound carcass measures, calving records, and records of disposal (n = 3,756 cows). There was a negative regression of AFC on RFI (–7.04 ± 3.36; P < 0.05), but otherwise no relationships (P > 0.12). Heifers in the upper quartiles had rib fat estimates of 0.7 ± 0.05 cm and differed from the very low quartile (0.60 ± 0.05 cm; P < 0.05). The regression coefficients (P < 0.001) of IMF on RFI and rib fat were 0.20 ± 0.06 and 0.067 ± 0.017, respectively. The regression coefficients (P < 0.01) of IMF, rib fat, and LA on DMI were 0.12 + 0.04, 0.079 ± 0.011, and 2.60 ± 0.35, respectively. The regression of LA on ADG was 4.47 ± 1.76 (P < 0.05). The regressions (P < 0.05) of IMF and rib fat on G:F were –3.66 ± 1.53, and –1.85 ± 0.44, respectively. Heritability estimates ranged from 0.2 ± 0.03 to 0.38 ± 0.03 for IMF, rib fat, and LA. Estimates of heritability for maternal traits were less than 0.1. Estimates of genetic correlations for carcass traits were greater than 0.23, and for AFC and CI was –0.90 ± 0.15. The regression coefficients (P < 0.05) of AFC on IMF and LA were –2.58 ± 1.06 and –0.50 ± 0.11). Minimal correspondence between feed efficiency, carcass, and fertility was detected in this work, and results in Beefmaster cattle appearing to be consistent with other breeds. | |
