A total of240 growing-finishing gilts (60 to 260 lb) was used to model accretion rates and the lysine:calorie ratio requirement based on lipid and protein growth. Real-time ultrasound measurements were used to estimate
lipid and protein contents. These estimates
then were translated into feed intake and
lysine requirements. Gilts were fed one of
eight different diet regimens, consisting of
four increasing lysine:calorie ratios and two
levels of fat (0 and 6%). Lipid and protein
deposition rates could effectively model feed
intake when pigs were fed lysine:calorie
ratios close to their requirement. The modeled accretion rates effectively predicted the differences between treatments in agreement with the growth performance data. The modeled lysine:calorie ratio requirement accurately predicted the lysine:calorie ratios that maximized growth, evaluated by either the predicted or the actual data.
