Heritability of beef cow metabolizable energy for maintenance

Most of the metabolizable energy that a cow uses during a production year is for maintenance; however, less is known about the heritability of maintenance compared to other traits that can be measured directly. Feed intake is a heritable trait in the mature cow and most of the feed consumed is used for maintenance. We hypothesized that maintenance energy was a heritable trait. Individual feed intake was measured for 84 or 85 d on 5 yr old pregnant cows (N = 887) from a pedigreed population of cattle that represent prominent breeds in the United States. Phenotypic mean (± SD) values were 654 ± 68 kg for cow body weight, 0.21 ± 0.24 kg/d for average daily gain, and 175 ± 17 d for midpoint fetal age. Dry matter intake averaged (± SD) 10.84 ± 1.41 kg/d. Metabolizable energy for maintenance was estimated by subtracting the metabolizable energy used for conceptus growth and tissue accretion from metabolizable energy intake. Metabolizable energy for maintenance averaged (± SD) 139 ± 18 ME kcal/d/BW kg0.75 and had a heritability of 0.31 ± 0.11. Cows have a moderate heritability for maintenance suggesting an opportunity for selection.