Sustainability & efficiency

Feed Intake Phenotypes of Growing Dairy Heifers that are the Progeny of Bulls with High or Low Breeding Values.

---

Abstract

It is important to consider feed efficiency when selecting for dairy cows that emit less methane (CH4), as the amount of feed eaten is related to CH4 emissions. Enteric CH4 is a source of digestible energy loss, suggesting that more feed efficient animals would produce less CH4. However, there are conflicting reports of the relationship between CH4 production and feed efficiency metrics. Two key efficiency metrics are residual feed intake (RFI) and feed conversion efficiency (FCE), both of which incorporate dry matter intake (DMI) and liveweight (LW) gain to assess the amount of feed eaten that is used for growth. The objective of this study was to compare the RFI and FCE of growing heifers with high or low CH4 yield.Dairy heifers (n = 396) of 6 to 15 months old were measured for DMI and LW in an indoor facility in one of four lots for 39 days each. The heifers were part of a study on the CH4 emissions of growing heifers sired by bulls with divergent CH4 estimated Breeding Values (metEBV) and were predominantly crosses of Holstein-Friesian and Jersey. Alfalfa hay cubes were offered ad libitum, with individual intake measured by Hokofarm RIC2Discover bins, CH4 emissions measured by GreenFeed, and LW measured three times per week. Linear regression was used to describe the relationships between DMI and day of trial, and LW and day of trial for each heifer. The respective equations were used to predict DMI and LW at the midpoint of the experimental period (day 20) to estimate an individual average DMI and LW, with the slope equal to the average daily LW gain (LWg), and the average LW used to calculate metabolic LW (LW0.75). The RFI for each heifer was obtained by regression of the predicted DMI against LW0.75 and LWg, and the FCE calculated by dividing the LWg by the predicted DMI. The effect of metEBV group on each variable of RFI, FCE, DMI, LW and LW gain were analysed by use of mixed models. In each model fixed effects of proportion of Holstein-Friesian breed (0 to 16) and lot (1 to 4), and a random effect of pen number (1 to 8) were included.Although CH4 production and yield were different between high and low metEBV heifer groups, there were no differences in DMI, LW, or LWg (Table 1). This resulted in no differences in RFI or FCE between groups of high and low metEBV heifers (Table 1). Therefore, we concluded that there were no differences in feed efficiency between heifers of high or low CH4 yield. Further research into the biological mechanisms of lower CH4 production is required.

Keywords: 2026

How to Cite:

McNaughton, L., Spaans, O., Spelman, R. & van Elzakker, P., (2026) “Feed Intake Phenotypes of Growing Dairy Heifers that are the Progeny of Bulls with High or Low Breeding Values.”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2283443. doi: https://doi.org/10.31274/wcgalp.24553

Rights: 1