Quantitative Threonine Requirement of the Weanling Pig

Publisher Website
Google Scholar
Abstract
Fifteen crossbred barrows averaging 24.3 lbs. were divided into 5 lots on the basis of starting wt. All lots received a ration containing 88.0% oorn which supplied 0.2% L-threonine to the finished feed. The corn was supplemented with 4.3% minerals, 0.5% liver extract, Terramycin HC1 (10 mg./lb. feed), crystalline B12 (10 [mu]g./Vo. feed), and 10 essential amino acids. Supplementary fat-soluble and water-soluble vits. were added to the evening feed in sufficient amts. to meet the daily requirement. The ration for Lot I contained no added threonine while the ration for other lots contained from 0.4% DL-threonine (Lot II) to 1.0% DL-threonine (Lot V). Diammonium citrate was added to the rations of Lots I-IV inclusive to equalize the N content to that of the highest threonine level (Lot V). Rations for all lots contained 13.2% protein. Durn the 35-day period on these diets the animals made avg. daily gains of 0.5 lb./pig on 0.2% L-threonine (Lot I), 1 lb./pig on 0.4% L-threonine (Lot II), 0.8 lb./pig on 0.5% L-threonine (Lot III), 1 lb./pig on 0.6% L-threonine (Lot IV), and 0.9 lb./pig on 0.7% L-threonine (Lot V). Based on these data and on the assumption that D-threonine is inactive, the L-threonine requirement of the weanling pig does not exceed 0.4% of the ration.