Genetic parameters of dairy cow energy intake and body energy status predicted using mid-infrared spectrometry of milk

摘要: Abstract Energy balance (EB) and energy intake (EI) are heritable traits of economic importance. Despite this, neither trait is explicitly included in national dairy cow breeding goals due to a lack routinely available data from which compute reliable values. Mid-infrared (MIR) spectrometry, performed during routine milk recording, an accurate predictor both EB EI. The objective this study was estimate genetic parameters EI predicted using MIR spectrometry. Measured were for 1,102 Irish Holstein-Friesian cows based on actual feed sink data. A subset these (1,270 test-day records) used develop equations predict EI, EB, daily change body condition score (ΔBCS) weight (ΔBW) the spectrum with or without yield also as variable. Accuracy cross-validation prediction 0.75, 0.73, 0.77, 0.70 ΔBCS, ΔBW, respectively. Prediction applied additional spectral data, yielding up 94,653 records MIR-predicted ΔBW variance component estimation. Variance components estimated repeatability animal linear mixed models. Heritabilities 0.20, 0.10, 0.07, 0.06, respectively; heritability estimates respective measured 0.35, 0.16, 0.08, correlation between 0.84 0.54, indicating that selection would improve true EB. Genetic phenotypic associations production body-change generally agreement, regardless whether considered. Higher-yielding animals higher had greater Predicted negatively genetically correlated (genetic correlation=−0.29) positively fat protein percent correlation=0.17 respectively). Least squares means 198 stratified low, average, high values (animal phenotypes not evaluation) 154.3, 156.0, 163.3 MJ/d, corroborating will, result differences