Lysine requirements for the mean in a population of growing pigs are well established, but estimates of the variability are not. That’s why researchers at the Swine Research and Technology Centre, University of Alberta, decided to study the topic.
For each pig, the phenylalanine (PHE) oxidation decreased linearly as the dietary lysine concentration increased until the requirement was reached. That means PHE oxidation was not different. The true digestible-lysine requirement ranged between 7.5 grams per kilogram and 10.6 grams per kilogram of diet for pigs between 45 pounds and 60 pounds. Mean requirements for all pigs was 9.1grams per day or 93.9 percent of the predicted requirement based on each pig’s mean body weight and energy intake.
Measured and predicted requirements were not different and lysine requirements of individual pigs were normally distributed. Two-thirds of the pigs had lysine requirements within 1 standard deviation from the mean.
Knowing the population’s variability allows you to more accurately calculate and choose a specified “safety factor.” This data can be used as a tool to adjust feeding strategies to various cost/revenue scenarios in order to maximize the margin over feed costs.