Profitability of different grouping criteria was simulated in a dairy farm with 153 lactating cows that were divided into three groups of high (79), medium (40) and low (34) cows based on the milk records. Animals were reassigned to the new groups based on the following criteria using a decision support tool and the same three groups scenario: fat corrected milk 4%, days in milk (DIM), dairy merit (fat-corrected milk (FCM)/body weight (BW)0.75), and cluster (cow’s energy and protein requirements). Four total mixed ration (TMR) were formulated for feeding three simulated groups in which group 2 (medium producing animals) could consume either concentrate type I or concentrate type II, whereas groups 1 and 3 always had their specific concentrate mixture. The number of animals in the high, medium and low producing groups altered following the re-grouping and the highest number of cows fell in either the new medium (FCM and dairy merit) or low (DIM and cluster) producing groups. Cluster and dairy merit grouping criteria resulted the most income over feed costs (IOFC) and maximum profitability compared to the milk records and other simulated scenarios. In all of the grouping criteria, when the second group consumed concentrate type II, the amount of IOFC was higher than situations where this group utilized concentrate type I. Overall, profitability and economic efficiency of the herd increased when a more precise grouping method was used. Furthermore, cluster method provided a liberty for choosing the type of concentrate for medium producing animals with a negligible effect on the calculated IOFC from the simulated data.

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