Submitted to: Journal of Animal Science
Publication Type: Abstract only
Publication Acceptance Date: 6/26/2003
Publication Date: 6/26/2003
Citation: Kendall, D.C., Kerr, B.J., Frank, J.W., Gaines, A.M., Ratliffe, B., Allee, G.L. 2003. Evaluation of the tid tryptophan:lysine ratio for late finishing barrows. Journal of Animal Science. 81 (1):139. Interpretive Summary:
Technical Abstract: A 29d experiment was conducted to determine the TID tryptophan:lysine (Trp:Lys) ratio for 91 to 124 kg barrows (n=210, TR4 x PIC C-22). Pigs were allotted in a completely randomized design and fed one of five dietary treatments with six replicates with each pen containing seven pigs. A four point titration was constructed with a basal diet (0.55% TID Lys, 3.47 Mcal ME/kg) formulated to contain 0.072% TID Trp (0.130 Trp:Lys). Additional amino acids were supplied from crystalline sources to meet minimum ratios. L-Trp was added at the expense of corn, creating the three additional Trp:Lys treatments (0.165, 0.200, and 0.235 Trp:Lys). A positive control, corn-soybean meal diet was formulated to contain 0.55% TID Lys, 3.47 Mcal ME/kg, and 0.110% TID Trp (.200 Trp:Lys). Blood samples of four pigs/pen were collected at d0 and d29 for the determination of blood urea nitrogen (BUN). For the trial, a linear increase in ADG (0.986, 1.11, 1.12, and 1.16 kg/day, respectively; P< 0.001) and ADFI (P< 0.01) was observed with increasing Trp:Lys. There were linear (P< 0.001) and quadratic improvements in d29 BW (P< 0.06) and G:F (0.304, 0.327, 0.327, and 0.330, respectively; P< 0.05) with increasing Trp:Lys. The change in BUN levels from d0 to d29 showed both a linear effect (P< 0.002) and a quadratic trend (P< 0.09) of increasing Trp:Lys. Pigs fed the 0.165 Trp:Lys diet had greater d29 BW, higher ADG, improved G:F, and lower BUN values than pigs fed the basal diet (P< 0.05), but did not differ (P > 0.21) from the 0.200 and 0.235 Trp:Lys diets for any parameter measured. Pigs fed the positive control diet had similar ADG (P > 0.60) and efficiency (2.99 vs. 3.07; P > 0.20) compared to pigs fed the 0.200 Trp:Lys diet, but did have higher d29 BUN (P < 0.001). This experiment demonstrates that a TID Trp:Lys ratio of 0.165 appears adequate in maintaining performance for pigs from 91 to 124 kg.