<p>This study presents a discrete-event stochastic simulation model designed to represent the productive and reproductive dynamics of a dairy herd. The model is first validated by comparing its steady-state outcomes with analytical results available in the literature, showing a close agreement that confirms its consistency and supports its use for more complex analyses. Once validated, the model is applied to examine the economic consequences of different management decisions, particularly those related to twin calvings. The results indicate that, under the most profitable voluntary culling strategy, herds without twin births achieve a monthly net profit of $134.55 per cow, while those experiencing twin calvings reach $113.89 per cow, which represents a loss of $185.98 per animal per parity. This magnitude is consistent with values commonly reported in previous studies. In addition, the sensitivity analysis shows that reducing the probability of twin births increases profit almost proportionally, with an improvement of around $2.06 per cow per month for every ten percent decrease. Altogether, these findings shed light on the economic impact of twin calvings and illustrate how simulation offers a flexible and practical framework for evaluating herd-level decisions under uncertainty.</p>