L-arginina suplementar para frangos de corte na fase final de criação (29 aos 42 dias)

Abstract

This study investigated the effects supplemental L-arginine (SArg) and its effects on lipid modulation and nutrient excretion of broilers fed with normal or reduced levels of crude protein (CP). Two experiments were conducted concomitantly with broilers Cobb® in each trial, males and females, from 29 to 42 days. The birds were distributed in a randomized block design (boxes and metal cages), in a 2x5 factorial arrangement (sex x SArg (0, 3, 6, 9 and 12 g kg -1 ), with six replicates of 23 birds for the boxes and three birds for the cages. The difference of the tests will consist of the nutritional level of crude protein: normal (Experiment 1- 187.5 g kg -1 ) and reduced (Experiment 2- 170.0 g kg -1 ). In both experiments were broiler performace, yield (carcass, cuts and abdominal fat-AF), breast chemical composition, blood lipid profile (triglycerides – TGL, colesterol total-TC and fractionated cholesterol – HDLc, LDLc, VLDLc), metabolizable coefficient of dry matter, ethereal extract and gross energy, nitrogen balance and nitrogen-corrected apparent metabolizable energy (AMEn). In Experiment 1 also evaluated the activity of the malic enzyme (ENZM) and glucose-6-phosphate dehydrogenase (G6PD) in the liver. The data were analyzed by two-way ANOVA, with sex compared by the F test, and the additional L-arginine by polynomial regression (linear, quadratic and linear response plauteau - LRP) or Scott-Knott test at the 5% level of probability through R software, version 3.5.1. Male broilers had better productive conditions than females in all trials. In the Experiment 1, the feed conversion data adjusted to the LRP model and improved (4.35%) up to 6.67 g kg -1 of SArg. However, AF reduced linearly, as well as CT and LDL. TGL and cVLDL showed a quadratic effect with reduction (15.37 and 13.09%, respectively) up to the level of 6.69 g kg -1 of SArg. SArg did not increase nitrogen excretion, but decreased EMAn at the levels of 9 and 12 g kg -1 . In the Experiment 2, the feed conversion data adjusted to the LRP model and improved (4.50%) up to 7.66 g kg -1 of SArg. There was an increase in the deposition of collagen in the broilers breast, but there was no significant change in AF. On the other hand, TGL had quadratic effect with reduction (17.48%) up to 7.63 g kg -1 of SArg and no increase in nutrient excretion and change in EMAn was observed. Thus, it can be concluded that, for the normal CP level, the SArg of 6.9 g kg-1 is efficient in decreasing lipogenesis and without altering the excretion of nutrients and EMAn. However, when the level of CP of the diet is reduced the level of SArg of 7.66 g kg -1 leads to improvement in the broiler performance without altering nutrient excretion and EMAn, reduces the metabolism of the TGL, and supposedly influences lipid metabolism