Optimum proportion of standardized ileal digestible sulfur amino acid to lysine to maximize the performance of 25-50 kg growing pigs fed reduced crude protein diets fortified with amino acids.

摘要: The study was conducted to determine the standardized ileal digestible (SID) sulfur amino acid (SAA) lysine (Lys) ratio required maximize performance of 25–50 kg pigs fed reduced crude protein (CP) diets fortified with crystalline acids. A total 360 crossbred (Duroc × (Landrace Large White)) pigs, weighing 25.6 ± 2.7 kg, were blocked by gender, litter, and initial body weight (BW) allotted 1 5 dietary treatments 6 pens per treatment 12 pen for a 35-day trial. basal diet based on corn, soybean meal, wheat bran formulated be deficient in SAA (50% proportion SID Lys). Graded levels dl-methionine added at expense order provide 55.6, 60.0, 65.6, or 70.0% Lys, respectively. constant Lys level 0.90% set so that second limiting (AA) all diets. Average daily gain (ADG) feed conversion (FCR) improved (linear quadratic, P < 0.05) increasing Lys. Increasing decreased serum urea nitrogen (SUN) (quadratic, 0.05). two-slope broken-line model estimated optimum 62.2, 61.5, 62.3% maximum ADG minimum FCR SUN, respectively, whereas curvilinear-plateau yielded an 63.8, 62.5, 61.5% Based average these estimates, we conclude low CP is 62.3%. This estimate higher than NRC (2012) recommendation 56.1% normal