ABSTRACT The present study was carried out to evaluate the effect of net energy levels in diets for barrows, from 70 to 100 kg, on performance, plasma parameters and carcass characteristics. Two experiments were carried out: in the first (Experiment I), a metabolism assay was carried out to estimate the net energy (NE) of experimental diets. Twelve crossbred barrows, averaging 85.74 ± 6.80 kg initial body weight, were distributed in a randomized block design with two metabolizable energy (ME) levels (3100 and 3500 kcal kg–1) with six replicates and one animal per experimental unit. In the second (Experiment II), 45 castrated male pigs were used, averaging 70.10 ± 1.26 kg of initial body weight distributed in a randomized block design, with five NE levels (2345, 2425, 2505, 2585, 2665 kcal kg–1), nine replicates and one animal per experimental unit. The increase in diet NE levels provided a linear reduction (p ≤ 0.00039) in average daily feed intake (ADFI). There was a quadratic effect on NE efficiency (p ≤ 0.0027), average daily gain (ADG), (p ≤ 0.0352) and the feed:gain ratio (F:G), (p ≤ 0.0024), the optimal levels being estimated at 2485, 2493 and 2533 kcal kg–1, respectively. Drip loss (DL) decreased (p ≤ 0.0001) as NE levels increased. There was also a linear decrease (p ≤ 0.0462) in the Minolta color parameter (+a*), due to the NE levels. Plasma parameters were not affected (p > 0.05) by NE levels. The dietary net energy levels affected the performance and meat quality of finishing pigs and the level of 2493 kcal kg–1 provided the best ADG.

ABSTRACT: The objective was to evaluate the impact of producing piglets fed diets with different crude protein (CP) levels through life cycle assessment and experimental data. In Trial I (performance), 28 crossbred barrow piglets, with an initial average weight of 15.3 ± 1.15 kg were divided into a randomized block design with four treatments, seven replications and one animal per experimental unit. In Trial II (nitrogen and phosphorus balance), 20 crossbred barrow piglets with an average weight of 21.4 ± 1.62 kg were divided in a randomized block design with four treatments, five replications and one animal per experimental unit. Four experimental feeds were evaluated: HighCP, CP18, CP17 and LowCP, with 19, 18, 17 and 16 % of CP, meeting the requirements of digestible amino acids through industrial amino acid (IAA) addition. From Trial I and II data, the environmental impact was calculated for global warming potential, acidification potential, eutrophication potential, cumulative energy demand, terrestrial ecotoxicity and land occupation (LO). Total nitrogen excretion decreased by 0.226 g d−1 for each 1 g of reduction on daily nitrogen intake. However, there was no statistical difference (p > 0.05) among experimental treatments for all impact categories. For LO, there was a reduction (p = 0.078) of impact with CP reduction, which was 8 % lower with the LowCP diet, in comparison with HighCP. Dietary CP reduction for piglets from 15 to 30 kg, through IAA supplementation, reduced the environmental impact under LO, considering soybean meal from southern Brazil and observed individual data of performance and excretion.

RESUMO O estudo teve como objetivo avaliar o uso de um complexo enzimático contendo α-amilase, ß-glucanase, fitase, celulase, xilanase e protease na dieta de suínos em crescimento e terminação sobre o desempenho (ganho diário de peso, consumo diário de ração e conversão alimentar), digestibilidade aparente da matéria seca, proteína bruta, energia bruta e custos de alimentação. Foram utilizados 80 suínos (machos castrados e êmeas), com aproximadamente 63 dias de idade, com peso inicial médio de 20,18 ± 1,98 kg, distribuídos em arranjo fatorial 5x2 (dietas x sexo), em delineamento de blocos ao acaso. Foram testados cinco tratamentos com oito repetições, sendo: CP: Dieta controle positivo (3300 kcal/kg na fase crescimento I e 3250 kcal/kg nas fases crescimento II e terminação)1; CN85: Dieta controle negativo com redução energética (85 kcal/kg EM); CE85: Dieta CN85 com adição de complexo enzimático; CN100: Dieta controle negativo com redução energética (100 kcal/kg EM); CE100: Dieta CN100 com adição de complexo enzimático. Nas dietas com redução energética de 100 kcal/kg de EM, o uso do complexo enzimático elevou o teor de proteína digestível durante o Crescimento II. A adição de complexo enzimático nas dietas com redução energética de 85 e 100 kcal/kg de EM aumentou os teores de energia digestível nas dietas de Terminação. Os resultados mostraram que para machos, recomenda-se o uso de complexo enzimático em dietas com redução de 85 kcal/kg de EM, durante os períodos de crescimento e terminação, pois melhora a conversão alimentar e é economicamente mais eficiente durante o Crescimento I. Para fêmeas, o uso do complexo enzimático não se justifica.

ABSTRACT The objective of this study was to evaluate the use of an enzyme complex-α-amylase, ß-glucanase, phytase, cellulase, xylanase and protease-in the feed of swine in growing and finishing phases, by assessing their performance (daily weight gain, daily feed intake, and feed conversion), dry matter, crude protein, and crude energy apparent digestibility, and the feed costs. Eighty pigs-castrated males, and females-of approximately 63 days of age and initial weight of 20.18±1.98 kg were distributed in a 5×2 factorial arrangement (diet × sex), in a randomized block design, with eight replications. The treatments used were: positive control diet consisted of 3,300 kcal/kg in the growth-I phase, and 3,250 kcal/kg in the growth-II and finishing phases; negative control diet with energy reduction of 85 kcal/kg of metabolizable energy (ME) (NC85); NC85 diet with addition of enzyme complex (EC85); negative control diet with energy reduction of 100 kcal/kg ME (NC100); NC100 diet with addition of enzyme complex (EC100). The addition of the enzyme complex to the diet with energy reduction of 100 kcal/kg ME increased the digestible protein content of the diet for the swine in the growth-II phase. The addition of the enzyme complex to the diet with energy reduction of 85 and 100 kcal/kg ME increased the digestible energy content of the diets for the swine in the finishing phase. The use of enzyme complex in diets with reduction of 85 kcal/kg ME for male swine in growing and finishing phases is recommended for improving feed conversion and economic efficiency during the growth-I phase. The use of enzyme complex is not justified for female swine.