Standardized ileal digestible tryptophan and lysine for 15–30 kg gilts

• Published in: The Journal of agricultural science Vol. 158; no. 7; pp. 624 - 631
• Main Authors: Pasquetti, T. J., Esteves, L. A. C., de Paula, V. R. C., Bonagúrio, L. P., Tanamati, W., Fachinello, M. R., Oliveira, N. T. E., Pozza, P. C.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.09.2020
• Subjects: Amino acids; Animal Research Paper; Body weight; Diet; Digestibility; Electrolytes; Lipoproteins; Lysine; Muscles; Nutrient deficiency; Nutrition research; Optimization; Physical growth; Proteins; Response surface methodology; Soybeans; Tryptophan; Ultrasonic imaging; Urea; Amino acids; performance; response surface; blood variables; metabolic interactions
• ISSN: 0021-8596; 1469-5146
• DOI: 10.1017/S0021859620000933

It was aimed to simultaneously study standardized ileal digestible (SID) tryptophan (Trp) and lysine (Lys) for gilts. A digestibility assay was previously conducted to determine the SID amino acid in the basal diet (low levels of SID Trp and Lys). Sixty-four gilts (15.04 ± 1.44 kg) were allotted to 16 diets in a 4 × 4 factorial arrangement (1.55, 1.85, 2.15 and 2.45 g/kg SID Trp and 9.72, 11.12, 12.52 and 13.92 g/kg SID Lys) with four replicates per treatment. Performance, longissimus muscle (LM), backfat thickness (BF) and blood variables were evaluated. An interaction was observed for G:F, and by response surface model, the optimum Trp level was achieved at 2.15 g/kg (0.159 g/MJ of ME). A quadratic effect of Trp was observed on body weight (BW) and average daily gain (ADG); the daily feed intake increased linearly as Trp increased. The optimum Trp levels of 2.25 and 2.24 g/kg were estimated for BW and ADG, respectively. The BF increased with increasing levels of Trp. There was a quadratic and linear effect of Trp and Lys, respectively, on the LM, in which the optimum Trp level was determined as 2.05 g/kg in the diet. Plasma urea nitrogen decreased as Trp and Lys levels increased. Using estimates provided by response surface, maximized G:F ratio was obtained at 2.15 g SID Trp/kg of diet and at least 13.92 g SID Lys/kg of diet is necessary to optimize the G:F for 15–30 kg gilts, providing a Trp:Lys ratio of 15.4:100.