Feed and intake growth curves represent the pattern of feed intake and growth in relation to live body weight or time. Once feed intake and growth curves are established, animal and financial performance can be evaluated and marginal costs can be determined. The objective of this study was to determine how many observations are required to establish feed intake and growth curves for the different groups of growing-finishing pigs. For the study, barrows and gilts were house separately and in different sized groups. Various mathematical functions were used to relate feed intake to live body weight and live body weight to time in the barn. These functions were characterized by the type of function and the number of variables included.
Results from the study showed a clear effect of sex on feed intake. Barrows consumed around 13% more feed than gilts. Live weight gain for barrows housed in groups of 1 and 5 tended to be lower at the largest group size. Gilts housed individually tended to gain faster than those housed in groups of 5 and 12. When mathematical functions were evaluated to relate feed intake to live body weight, it was found that exponential functions were just as accurate as asymptotic. It was noticed that in some pens, the weekly feed intake was substantially different from the actual feed intake curve. Thus it is important to get multiple observations, but it is more meaningful to take feed intake measurements at two week periods. It was also observed that the difference in feed intake between sexes is increased, as the pigs grow heavier. For this reason it is suggested that the difference in gilt and barrow feeds should be larger during the finishing phase than the grower phase.
The general pattern of feed intake and growth in gilts and barrows that were housed in various group sizes was accurately represented by various mathematical functions that included only two parameters each. This means that the number of observations required to establish feed intake and growth curves can be reduced.