Random regression models, a novel approach to growth curves

A pig changes over time: it puts on weight and eats more, as it becomes larger. Different pigs grow in a different manner. There is evidence that these differences in growth patterns between pigs are caused by genetic factors. This gives the opportunity to select for these different growth patterns, to better meet the demands of markets that differ in desired slaughter weight, eg Bacon, fresh pork, and Italian Parma ham. In Australia, slaughter weights have increased over the past two decades (Figure 1), and the trend is that slaughter weights will keep increasing. This development requires more knowledge on the latter part of the growth curve.