Edit in JSFiddle

$("#owl-example").owlCarousel({
    itemsCustom: [[600,5],[500,4],[400,3],[300,2],[200,1]]
});

<div id="owl-example" class="owl-carousel">
    <div class="block red">1</div>
    <div class="block green">2</div>
    <div class="block blue">3</div>
    <div class="block red">4</div>
    <div class="block green">5</div>
    <div class="block blue">6</div>
    <div class="block red">7</div>
    <div class="block green">8</div>
    <div class="block blue">9</div>
    <div class="block red">10</div>
    <div class="block green">11</div>
    <div class="block blue">12</div>
</div>

.block {
    display: block;
    width: 100px;
    height: 100px;
    font-size: 20px;
    font-weight: bold;
    text-align: center;
    line-height: 100px;
    color: #888888;
}

.red {
    background: #FFCCCC;
}
.green {
    background: #CCFFCC;
}
.blue {
    background: #CCCCFF;
}