Determining the Effects of Tryptophan Biomass on Growth Performance of 25- to 50-lb Nursery Pigs

A total of 315 barrows (DNA; 200 × 400; initially 24.9 lb) were used in a 21-d growth trial evaluating the effects of feeding TRP Pro (CJ America-Bio, Downers Grove, IL) as a source of Trp on nursery pig performance. Pigs were weaned at approximately 21 d of age, placed in pens based on initial body weight (BW), and fed common starter diets for 21 d. On d 21 after weaning, considered d 0 of the study, pigs were weighed and pens were allotted to 1 of 4 dietary treatments with 5 pigs per pen and 15 or 16 pens per treatment. Dietary treatments included a negative control (16% SID Trp:Lys ratio), positive control (21% SID Trp:Lys ratio from crystalline Trp), or diets containing Trp with biomass to provide 21 or 23.5% standardized ileal digestible (SID) Trp:Lys ratios (included at 0.104 or 0.156% of the diet, respectively). Diets were corn-soybean meal-based and contained 1.25% SID Lys with other amino acids set to meet or exceed NRC requirement estimates. The TRP Pro contained 60% Trp per the supplier’s specifications. Growth data were analyzed as a randomized complete block design using the PROC GLIMMIX procedure of SAS with pen as the experimental unit. Overall (d 0 to 21), pigs fed the 21% Trp:Lys ratio from crystalline Trp or Trp with biomass had increased (P \u3c 0.05) average daily gain (ADG) compared to pigs fed the negative control diet, with pigs fed the 23.5% Trp:Lys ratio with biomass intermediate. There was no evidence for difference in overall average daily feed intake (ADFI); however, pigs fed the 21% Trp:Lys ratio from Trp with biomass had improved (P \u3c 0.05) feed efficiency (F/G) compared to the negative control diet, with others intermediate. In conclusion, TRP Pro appears to be a suitable alternative to crystalline Trp in nursery pig diets but further evaluation at higher inclusion levels is needed