-Two experiments were carried out to evaluate the reduction of crude protein (CP) in diets supplemented with synthetic amino acids for piglets of 15 to 30 kg. In the performance assay (Exp I), 60 piglets with initial weight of 15.34±0.87 kg and final weight of 30.08±1.59 kg were distributed in a randomized block design with six replicates, five treatments and two animals per experimental unit. The treatments consisted of five diets in which the CP was reduced by 1.5 percentage points, resulting in low-protein diets (19.24, 17.74, 16.24, 14.74 and 13.24%), meeting the requirements of amino acids with inclusion of L-lysine, DL-methionine, L-threonine, L-tryptophan, L-valine and L-isoleucine. The average daily gain and feed conversion according to the Linear Response Plateau model (LRP) were estimated at 14.23 and 14.79% of CP, respectively. As the CP levels were reduced, there was an increase in the essential:non-essential amino acids ratio. The plasma urea concentration decreased linearly, indicating that there was a better use for amino acids with the CP reduction. In the nitrogen balance (Exp II), 30 crossbred barrow piglets with average weight of 21.69±4.46 kg were housed in metabolic cages, distributed in a completely randomized design with five treatments and six replicates, and the experimental unit consisted of a piglet. The biological protein value in the diets remained above the ideal (70%), in which the level of 13.24% CP corresponded to the highest value. There was no difference in levels of urea in blood and urine. Reduction of protein levels is efficient in decreasing the pollution effect in the excreta, with lower nitrogen excretion in feces and urine.

Glycerin is a major co-product resulting from biodiesel production, and it has been proposed as a highenergy source for use in swine diets. However, it is necessary to determine the nutritional value of neutral semi-purified glycerin (NSPG). In this study two experiments were carried out to determine the nutritional value, evaluated the performance and economic feasibility of starting piglets fed on neutral semi-purified glycerin. A digestibility trial (Experiment I) was conducted using 30 crossbred barrows with an initial average body weight of 42.91±1.58 kg. The glycerin levels used in the digestibility assay were 4, 8, 12 and 16% of the basal diet (corn + soybean meal based). The digestible energy (DE) and metabolizable (ME) energy values of glycerin were estimated by regression of DE and ME (kcal/kg) intake associated with glycerin vs. glycerin intake (kg). The values (as-fed-basis) of DE and ME (kcal/ kg) obtained were 3,298 and 2,531, respectively. In Experiment II, 100 piglets (50 gilts and 50 barrows) with BW = 15.14±0.06 to 30.28±0.65 were allotted in a randomized design using four inclusion levels (3.5, 7.0, 10.5 and 14%) of NSPG. There were ten replicates with two piglets per experimental unit. Additionally, a control diet containing no glycerin (0%) was formulated. The results show it is feasible to use up to 14% NSPG in piglet feed without impairing performance and plasma chemistry. Key words: Biodiesel, digestibility, glycerol, performance ResumoA glicerina é o principal coproduto da produção do biodiesel, e é proposta sua utilização como uma fonte de alto potencial energético na alimentação de suínos. No entanto é necessário determinar seu valor nutricional da glicerina semi-purificada neutralizada (GSPN). Neste estudo, foram conduzidos dois experimentos com o objetivo de determinar o valor nutricional, avaliar o desempenho e a viabilidade econômica de leitões alimentados com GSPN. O ensaio de digestibilidade (Experimento I) foi conduzido utilizando 30 suínos mestiços com peso vivo médio inicial de 42,91 ± 1,58 kg. Os níveis de substituição da ração referência pela glicerina foram 4, 8, 12 e 16%. Os valores de energia digestível (ED) e metabolizável (EM) das glicerinas foram estimados pela análise de regressão do consumo de ED e EM (kcal/kg) associada com a glicerina vs. consumo de glicerina (kg). Os valores de ED e EM (kcal/ kg), na matéria natural, obtidos foram de: 3.298 e 2.531 kcal/kg respectivamente. No experimento II, 100 leitões (50 fêmeas e 50 machos cadastros) com peso vivo inicial de 15,14±0,06 a 30,28±0,65 kg) foram distribuídos em delineamento de blocos casualizados, com quatro níveis de inclusão (3,5; 7,0;

Two experiments were carried out aiming to determine the nutritional value and to evaluate performance, carcass traits and economic feasibility of growing-finishing pigs fed on two types of crude glycerine (CG) which were made from vegetable oil (CGS), and mixed of animal fat + soybean oil (CGA). In Experiment I, a digestibility assay were carried out using 32 (24 test diet and 8 basal diet) cross breed pig (45.08 ± 4.11 kg). The experimental unit consisted of one pig, with a total of four experimental units per diet. Glycerine levels used in the digestibility assay were 6, 12, and 18% of the basal diet (corn + soybean meal based). The values (as-fed-basis) of DE and ME (kcal/kg) obtained were: CGS= 5,040 and 4,481; CGA= 5,234 and 4,707, respectively. In the Experiment II, 63 pigs, were allotted in a completely randomized design in 2 x 4 factorial scheme, with two types of crude glycerine (CGS and CGA) and four inclusion levels (3, 6, 9, and 12%). Additionally, it was formulated a control diet containg no glycerine (0%). There was no interaction (P≥0.05) among levels of CG and types of glycerine sources, and the regression analysis indicates no effects (P≥0.05) of crude glycerine inclusion on performance and carcass traits (backfat thickness and loin depth). The results suggest that it is feasible to use up to 12% of both crude glycerine (made from soybean oil and mixed) on growing-finishing pigs diet, without impairing performance and carcass traits, besides providing a reduction of about 11% on feeding cost. Key words: Biodiesel, co-product, digestibility, glycerol ResumoForam conduzidos dois experimentos com o objetivo de determinar o valor nutricional e avaliar o desempenho, característica de carcaça e viabilidade econômica de suínos em fase de crescimento e terminação alimentados com rações contendo dois tipos de glicerinas brutas: GBV -oriunda de óleo vegetal (soja) e GBM -mista, oriunda de gordura animal e óleo de soja. No Experimento I, foi conduzido um ensaio de digestibilidade com 32 (24 rações testes e 8 ração referência) suínos (45,08 ± 4,11 kg) mestiços. A unidade experimental consistiu-se de um suíno, totalizando quatro unidades experimentais por ração. Os níveis de substituição da ração referência pela glicerina foram 6, 12 e 18%. Os valores de ED e EM (kcal/kg), na matéria natural, obtidos foram: GBV= 5.040 e 4.481 e GBM= 5.234 e 4.707, respectivamente. No Experimento II, foram utilizados 63 suínos, distribuídos em delineamento inteiramente casualizados, em esquema fatorial 2 x 4, sendo dois tipos de glicerina bruta (GBV e GBM) e quatro níveis de inclusão (3, 6, 9 e 12%). Adicionalmente, foi formulada uma ração testemunha, não contendo glicerina (0%). Não houve interação (P≥0,05) entre os níveis de inclusão e o tipo da glicerina bruta. A análise de regressão indica que não houve efeito (P≥0,05) do nível de inclusão das glicerinas brutas sobre o desempenho e característica de carcaça (espessura de toucinho

The experiment was carried out to evaluate performance, plasma variables, carcass traits and meat quality of growing-finishing pigs fed on diets with increasing levels of neutralized semi-purified glycerin (NSPG). Eighty growing pig (30.31 6 0.47 to 60.41 6 0.87 kg) and 80 finishing pigs (60.45 6 0.46 to 90.99 6 0.83 kg) were enrolled. Pigs were allotted in a randomized block design with four inclusion levels of NSPG (3.5, 7.0, 10.5 and 14%), mainly substituted the corn in diets. The experiment included 16 replicates and one pig per pen. Additionally, there was a control diet (0% NSPG). At the end of the finishing phase, all pigs were slaughtered to evaluate quantitative carcass traits and meat quality. The regression analysis showed no effect (p > 0.05) of NSPG on growth performance, backfat thickness and loin depth in the growing and finishing phases. As to plasma variables, cholesterol and triglycerides increased linearly only in the finishing phase. A linear increase was obtained in quantitative carcass traits (p < 0.05), such as hot carcass weight, hot carcass yield, cold carcass weight and cold carcass yield. As to meat quality traits, there was a quadratic effect for water drip loss and total lipids with inclusion levels of NSPG. As a whole, NSPG can be used up to 14% in the feed of growing and finishing pigs (30-90 kg) without impairing performance, plasma variables and quantitative carcass traits and meat quality. However, its use may increase the cost of the diet depending on the feedstuffs prices.ARTICLE HISTORY

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