Feed efficiency is an important aspect of dairy cattle productivity, and is a term used to describe the relative ability of a cow to convert feed into milk or milk components. Because feed intake is expensive to accurately measure on large populations, incorporation of feed efficiency traits in genetic selection programs has been difficult. Recently, several measures of feed efficiency have been discussed as potential traits for genetic analysis, and technological advances have allowed the collection of data on numerous animals. Data on related traits such as body weight or body condition score is also being measured. To produce breeding value estimates for feed efficiency, it is important to understand the genetic and phenotypic correlations between relevant traits. Furthermore, physiological aspects, such as the stage of lactation, must be considered.Peak production normally occurs between 6 to 8 weeks (42 to 56 DIM) after calving and coincides with the phase of negative energy balance in which cows use more energy than they can take in. When considering feed efficiency, it is important to split the lactation between negative and positive energy balance periods to ensure that the important physiological, metabolic and nutritional changes during the period after calving have no negative effects on cow health. In this study, 3,244 daily feed intake and milk parameter, and 1,024 weekly body weight records were collected on 204 Canadian first lactation cows from 2014 to 2018. These records were used to calculate dry matter intake (DMI) and energy corrected milk (ECM). Parameters (heritability estimates and both genetic and phenotypic correlations) were estimated for DMI, metabolic body weight (MBW) and ECM at 2 time-periods: a) 5–60 DIM, and b) 60–150 DIM using AIREML methodology. The results of this parameter estimation provide a basis for the development of breeding value estimation procedures and a subsequent selection index for feed efficiency.