Milking cows dominate dairy farm greenhouse gas (GHG) emissions. However, replacement heifers also contribute to farm GHG emissions, increasing the emission intensity of milk production (GHG emissions per unit of milk) for the farm.
In northern Australia, heifers generally graze poorer-quality subtropical pastures. In the absence of energy-dense supplementary feed during periods of low pasture growth and/or quality, daily liveweight (LW) gain can be restricted.
This desktop modelling study examined the time required and enteric methane (CH4) emissions produced in raising dairy heifers to a target LW for first mating by feeding a diet assuming constant and variable nutritive values.
Maintaining heifers on high quality diets increased daily LW gain and lowered total enteric CH4 emissions between weaning and mating. Heifers calving at an earlier age are therefore more likely to spend a longer period of their lifetime producing milk thus reducing their lifetime emission intensity of milk production.
Citation: Christie K. M., Harrison M. T., Trevaskis L. M., Rawnsley R. P., Eckard R. J. (2016) Modelling enteric methane abatement from earlier mating of dairy heifers in subtropical Australia by improving diet quality. Animal Production Science 56, 565–573.
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Published on: 07 Apr 2016 12:12pm