Figure 4. Graphical representation of results of data presented in Tables 1 and 2 subjected to linear regression and the Randall power model (references in parentheses). The Manitoba model is a hoerl equation where y = (37.53)(0.9969)^W(W^0.5008) and is derived from the data in Table 1 with the point (104 kg, 305 kg BW/m²) excluded. The Australian data most closely fit a hoerl equation where y = (46.81)(0.9985)^W(W^0.423) is derived from the data in Table 2 and extrapolated down to 5 kg BW. Statistical information on these 2 models is given in Table 3. The Randall formula is a power equation, y = (100)(W^0.225), which is a conversion to a pressure based equation of the original area based equation, A = 0.01M^0.78, where A is the minimum area in m² and M is mass in kg BW (13). In all the models depicted graphically, y is the loading pressure in kg BW/m² and W is the average animal weight in kg. The area within the trapezoid approximates the recommendation from the pig code (11).