Níveis de triptofano e lisina digestíveis ileais estandardizadas para suínos machos em fase de terminação

Abstract

The objective of this study was to determine the optimal levels required in grams per dayas well as the standardized ileal digestible (SID) Trp:Lys ratio, for 75- to 100-kg immunized and 110- to 135-kg immunocastrated male pigs, and its effects on behavior, growth performance, apparent total tract digestibility, blood parameters, carcass traits and meat quality. In Experiment I, 64 crossbred male pigs (Landrace x Large White) with average initial body weight of 75.55 ± 4.11kg were assigned to a 4x4 factorial arrangement,using a randomized complete block design, based on four levels of SID Trp (1.1; 1.5; 1.9 and 2.3g of Trp/kg of diet) and four levels of SID Lys (6.50, 8.00, 9.50 and 11.00g of Lys/kg of diet), composing 16 treatments with four replicates of one animal per experimental unit (from 75 to 100 kg). In Experiment II, 64 crossbred male pigs (Landrace x Large White) with average initial body weight of 135.63±8.21kg were distributed in a 4x4 factorial arrangement, with four levels of SIDTrp (0.75, 1.05, 1.35 and 1.65g of Trp/kg of feed) and four levels of SID Lys (4.0, 5.5, 7.0 and 8.5g of Lys/kg of diet), until they reached a body weight of 135 kg. To determine growth performance the final body weight (FBW), average daily feed intake (ADFI), daily body weight gain (DBWG) and feed efficiency (FE) variables were assessed. To evaluate the blood biochemical parameters, albumin (ALB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP), glucose (GLU), globulin (GLOB), total proteins (TP) and plasma urea nitrogen (PUN) were assayed using commercial kits. Theresponse surface methodology was adopted as a statistical procedure, using polynomial regression models. In experiment I, there was a quadratic effect of SID Trp for FBW (P=0.002), DBWG (P=0.0002) and ADFI (P=0.006), which were estimated at 1.90, 1.99 and 2.00 g/kg of SID Trp, respectively. There was a linear effect of SID Trp (P=0.022) on PUN. The levels of SID Trp presented a quadratic effect on the behaviors of sitting (SIT) (P=0.0009), sleeping (SLP) (P=0.011) and idle (P=0.030), which were estimated at 0.16, 1.75 and 1.80 g/kg, respectively. Also, for SID Lys,SIT (P=0.013) and SLP (P=0.001) were estimated at 0.33 and 1.56 g/kg, respectively. There was an interaction effect of SID Trp:Lys on the apparent digestibility coefficients of dry matter (ADCDM)(P=0.0002), crude protein (ADCCP) (P=0.0002), organic matter (ADCOM)(P=0.0003) and gross energy (ADCGE)(P=0.00014), digestible dry matter (DDM)(P<.0001), digestible protein (DP)(P=0.0001), digestible organic matter (DOM)(P =0.0002), and digestible energy (DE) (P=0.0014). There was aquadratic effect forSID Trp levels on DOM (P=0.544) and DE (P=0.0004), which were estimated at 1.82 and 1.81 g/kg of SID Trp, respectively. A quadratic effectwas also observed forSID Lys levels on DOM (P=0.011), estimated at 10.16. The optimal SIDTrp levels, for pigs from 75to 100kg, that improvedthe growth performance variables FBW, DBWG and ADFI were 1.90, 1.99 and 2.00 g/kg of SID, respectively, favoring linear reduction of PUN and increasing the use of dietary crude protein. Furthermore, the 0.231 SIDTrp:Lys ratio (1.55 g/kg of SID Trp and 6.5 g/kg of SID Lys) was considered as an assessment indicator for the behavioral variables. Experiment II showed a quadratic effect (P<0.05) of Trp levels on FBW, DBWG, ADFI and FE, in which 1.36, 1.36, 1.30 and 1.77 g/kg SID Trp were estimated, respectively. In addition, there was a quadratic effect of Lys on FE, estimated at an optimal level of 7.19 g of SID Lys/kg of feed. For blood parameters, the TP and PUN variables showed a quadratic effect of SID Trp and Lys, with estimated critical points at 1.35 and 6.72 g/kg, respectively. For behavioral assessments, SLP, SIT and drinking (DRK) had a quadratic effect of SID Trp levels, estimated at 1.44, 0.76 and 1.68 g/kg, respectively. For the metabolism assay, there was an interaction effect of SID Trp:Lyson ADCDM (P=0.0002), ADCCP (P=0.0002), ADCOM (P=0.0003), ADCGE (P=0.00014), DDM (P<0.0001), DP (P=0.0001), DOM and DE (P=0.0014). A quadratic effect was observed for SID Trp levels on DOM (P=0.544) and DE (P=0.0004), which were estimated at 1.82 and 1.81 g/kg of SID Trp, respectively. The optimal SIDTrp levels, for pigs from 75to 100kg, that improved the growth performance variables FBW, DBWG and ADFI were 1.90, 1.99 and 2.00 g/kg of SID, respectively, favoring linear reduction of PUN and increasing the use of dietary crude protein. Fur thermore, the 0.231 SID Trp:Lys ratio (1.55 g/kg of SID Trp and 6.5 g/kg of SID Lys) was considered as an assessment indicator for the behavioral variables. Experiment II showed a quadratic effect (P<0.05) of Trp levels on FBW, DBWG, ADFI and FE, in which 1.36, 1.36, 1.30 and 1.77 g/kg SID Trp were estimated, respectively. In addition, there was a quadratic effect of Lys on FE, estimated at an optimal level of 7.19 g of SID Lys/kg of diet. For blood parameters, the TP and PUN variables showed a quadratic effect of SID Trp and Lys, with estimated critical points at 1.35 and 6.72 g/kg, respectively. Forbehavioral assessments, SLP, SIT and drinking (DRK) had a quadratic effect of SID Trp levels, estimated at 1.44, 0.76 and 1.68 g/kg, respectively. For the metabolism assay, there was an interaction effect of SID Trp:Lyson ADCDM (P=0.0002), ADCCP (P=0.0002), ADCOM (P=0.0003), ADCGE (P=0.00014), DDM (P<0.0001), DP (P=0.0001), DOM and DE (P=0.0014).