Abstract #150
Section: ADSA Production PhD Oral Competition (Graduate)
Session: ADSA Production PhD Oral Competition
Format: Oral
Day/Time: Monday 3:45 PM–4:00 PM
Location: Room 262
Session: ADSA Production PhD Oral Competition
Format: Oral
Day/Time: Monday 3:45 PM–4:00 PM
Location: Room 262
# 150
Development of a robust, net energy-based measure of feed efficiency in dairy cattle.
D. J. Seymour*1,2, A. Cánovas2, T. C. S. Chud2, J. P. Cant1, V. R. Osborne1, F. S. Schenkel2, F. Miglior2, 1Centre for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada, 2Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada.
Key Words: dairy cattle, feed efficiency, net energy
Development of a robust, net energy-based measure of feed efficiency in dairy cattle.
D. J. Seymour*1,2, A. Cánovas2, T. C. S. Chud2, J. P. Cant1, V. R. Osborne1, F. S. Schenkel2, F. Miglior2, 1Centre for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada, 2Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada.
Residual feed intake (RFI), along with the related residual net energy intake (REI), are some of the most widely used measures of feed efficiency in dairy cattle. As these methods are regression-based, efficiency is expressed relative to the animals used to estimate the regression coefficients. Furthermore, measures of feed efficiency are highly influenced by the mobilization of body reserves to support lactation, leading to the inflation of efficiency estimates particularly in the early stages of lactation when animals are in negative energy balance. The objective of this study was to develop a measure of feed efficiency based on the NRC net energy model that can be estimated irrespective of contemporary group and account for endogenous energy. Daily records of feed intake, milk production, body weight and body condition score were collected on first-lactation Holstein heifers (n = 40) over the first 150 DIM. Smoothing splines were used to generate smooth curves for each input and interpolate any missing records. Based on the smoothed records, daily measures of gross feed efficiency (GFE), return over feed costs (ROFC), RFI, and REI were estimated. All net energy modeling was based on the NRC net energy model. The amount of net energy for lactation (NEL) released or captured from body reserves was calculated using the daily change in bodyweight and body condition score. The available NEL per day was estimated as the amount consumed in the diet plus or minus the amount released or sequestered by body reserves, respectively. Lactation efficiency was then estimated as the proportion of available NEL captured in milk. Lactation efficiency was well correlated (r > 0.65; P < 0.001) with GFE, ROFC, RFI and REI and did not exhibit inflation in early lactation as seen with other measures. With the increased adoption of precision management technologies, this measure of feed efficiency represents a promising method of determining an individual animal’s feed efficiency at any stage of lactation and independent of other animals.
Key Words: dairy cattle, feed efficiency, net energy
