ASAS/ADSA Midwestern Meeting ABSTRACT
The purpose of the experiment was to assess the response of 10-kg pigs to increasing levels of dietary threonine when fed as part of an ideal protein for 28 days. The experiment consisted of a growth study and a nitrogen retention study. The basal diet contained 10 g lysine, 3.6 Mcal DE and 3.6 g threonine per kilogram; to which 0, .8, 1.6, 2.4, 3.2 or 4.0 g of threonine was supplemented per kilogram of diet. Forty-eight crossbred pigs with an average body weight of 10 kg were blocked by weight and randomly assigned to the six experimental diets for a 28-day growth assessment. Increasing threonine levels resulted in linear (P<.05) and quadratic (P<.05) improvements in final body weight, ADG, and feed efficiency. No significant differences were observed for feed intake (P>.05). Twenty-four crossbred pigs with an average body weight of 15 kg were blocked by weight, randomly assigned to the six experimental diets and maintained in metabolism crates for a 10-day nitrogen balance study. Increasing threonine levels resulted in linear (P<.05) improvements in biological value and net protein utilization with a linear (P<.05) decrease in urinary nitrogen. Quadratic (P<.05) responses were observed for nitrogen absorption and nitrogen retention. No further improvement in performance and nitrogen retention was observed beyond 1.6 g of supplemental threonine per kilogram of diet. These data indicate that threonine supplementation improves growth performance and nitrogen retention in nursery pigs.
Key Words: Threonine, Ideal Protein, Nitrogen Retention