Exigência de treonina, com base no conceito de proteína ideal, de alevinos de tilápia-do-nilo

Abstract

RESUMO -Avaliou-se o efeito dos níveis de treonina digestível, com base no conceito de proteína ideal, em rações com 1,35% de lisina digestível sobre o desempenho de alevinos de tilápia-do-nilo (Oreochromis niloticus). Utilizaram-se 432 alevinos revertidos de tilápia, linhagem tailandesa, com peso inicial de 1,64 ± 0,03 g, em delineamento inteiramente ao acaso, com seis tratamentos, cada um com seis repetições, e doze peixes por unidade experimental. Os tratamentos consistiram de cinco rações com diversas relações treonina:lisina digestível (69,0; 74,0; 79,0; 84,0 e 89,0%) e relação metionina + cistina:lisina digestível de 70,0% e uma ração com relação treonina:lisina digestível de 84,0% e de metionina + cistina:lisina with water supply, controlled temperature and individual aeration, and ad libitum fed six times a day for 30 days. Performance, body composition, protein and fat depositions and nitrogen retention efficiency of fishes were evaluated. Consumption of feed, body protein content and body protein deposition increased in a linear fashion in accordance to threonine:digestible lysine in the diet, however, was not affected by the increase of dietary methionine + cystine:digestible lysine. Total or digestible threonine levels that provided the best results of performance of Nile tilapia fingerlings were 1.11 and 0.99%, while the levels that promoted better body protein deposition were 1.43 and 1.28%, which correspond to threonine:total lysine ratio of 71.0 and 69.0% and threonine:digestible lysine of 90.0 and 89.0%.

Threonine to lysine ratio in diets of tambaqui juveniles (Colossoma macropomum)

“…The weight gain and specific growth rate increased (P < 0.05) in a quadratic manner as a result of the ratio of threonine to lysine in the diet up to the estimated ratios of 76.96% (1.116% digestible threonine) and 76.06% (1.106% threonine), respectively (Figure 1; Tables 2, 3 and 4). This increase in performance can be attributed to the better balance of the protein fraction of the diet with the increased level of threonine, which allowed better use of the amino acids, favoring the deposition of body protein and improved fish performance, which was similar to the observations by Bomfim et al (2008) Table 3. Body moisture content (MC), body fat (BF), body protein (BP), body protein deposition (BPD), body fat deposition (BFD), and nitrogen retention efficiency (NRE) in tambaqui juveniles and summary of the analyses of variance comparing effects of diets with different threonine:digestible lysine ratios in the Table 3.…”

“…lysine ratio (%) Variable IW (g) RC (g) DTC (mg) WG (g) SGR (%/day) FC (g/g) PEG (g/g) TEG ( The weight gain and specific growth rate increased (P < 0.05) in a quadratic manner as a result of the ratio of threonine to lysine in the diet up to the estimated ratios of 76.96% (1.116% digestible threonine) and 76.06% (1.106% threonine), respectively (Figure 1; Tables 2, 3 and 4). This increase in performance can be attributed to the better balance of the protein fraction of the diet with the increased level of threonine, which allowed better use of the amino acids, favoring the deposition of body protein and improved fish performance, which was similar to the observations by Bomfim et al (2008) in Nile tilapia (Oreochromis niloticus). The weight gain and specific growth rate increased (P < 0.05) in a quadratic manner as a result of the ratio of threonine to lysine in the diet up to the estimated ratios of 76.96% (1.116% digestible threonine) and 76.06% (1.106% threonine), respectively (Figure 1; Tables 2, 3 and 4).…”

“…However, a quadratic response was observed in the fish growth rate in the present study, with the best result obtained with the estimated level of 0.89% digestible threonine in the ration. The values of the estimated threonine:digestible lysine ratio based on the above-mentioned variables resemble the value of 74% (1.35% threonine) determined by Silva et al (2006), are higher than the 69% (0.930% threonine) recommended by Bomfim et al (2008), and lower than the 88% (1.358% threonine) observed by Takishita (2012), all in trials with Nile tilapia.…”

“…To determine the dietary ratio of a certain essential amino acid (lysine) needed in the diets of fish by Boisen (2003), levels of lysine were set at values considered sub-optimal to ensure that it was the second most limiting amino acid in the basal ration, and the other essential amino acids or amino acid:lysine ratios were set at amounts higher than the required values reported in the literature. In this way, the response to the increment in the levels of the evaluated amino acid could be maximized, as a result of lysine levels being a limiting factor (BOMFIM et al, 2008;BOMFIM, 2013;TAKISHITA, 2012;VIANA, 2012).…”

Nutritional innovations on amino acids supplementation in Nile tilapia diets

“…Threonine supplementation is associated to tilapia growth (Bomfim et al, 2008a) and fillet yield improving , specially in diets formulated based on soybean protein (amino acids), indicating that threonine is a limiting amino acid in soybean meal when meat production is considered.…”