Two experiments were performed to determine the digestibility of diets with crude protein (CP) reduction supplemented with amino acids (18.15; 17.15; 16.15 and 15.15%) to growing pigs (30–50 kg), to assess the use of nutrients and account for the manure excretion, and to evaluate the performance, backfat thickness, Longissimus lumborum depth, and plasma urea, aiming to evaluate the environmental impact through life cycle assessment (LCA); for the first time in Brazil interacting experiments were developed to evaluate the CP reduction and LCA. The CP reduction resulted in greater daily weight gain (p = 0.011), final weight (p = 0.020), better use of N and P, through the greater N and P retained (p = 0.003 and p = 0.017, respectively). There was a linear reduction in acidification potential (p = 0.015), eutrophication potential (p = 0.001), and land occupation (p = 0.005) when dietary CP decreased from 18.15 to 15.15%. The reduction in CP and supplementation of amino acids in diets for growing pigs (30–50 kg) improved final and daily weight gain. Through LCA, and performance and metabolism data, it was concluded that for the acidification, eutrophication and land occupation categories, impacts were reduced as the protein concentration was reduced.

Inosine 5′-monophosphate (5′-IMP) is an essential nucleotide for de novo nucleotide biosynthesis and metabolism of energy, proteins, and antioxidants. Nucleotides are conditionally essential, as they cannot be produced sufficiently rapidly to meet the needs of the body in situations of oxidative stress or rapid muscle growth. A deficient intake of nucleotides can result in decreased ATP and GTP synthesis and impaired metabolism. We demonstrated that supplementation of finishing pig diets with 5′-IMP reduces the relative weight of the liver, and increases oxygen consumption during mitochondrial respiration without changing the ADP/O ratio, indicating an increase in the respiratory efficiency of liver mitochondria. We also observed a reduction in liver lipid peroxidation and an increase in muscle creatine. Moreover, 5′IMP supplementation increases slaughter weight, lean meat yield, sarcomere length, and backfat thickness in finishing barrows, demonstrating influence on protein metabolism. We suggest that 5′-IMP supplementation increase the mitochondrial respiratory capacity when the liver metabolic activity is stimulated, enhances antioxidant defense, and promotes muscle growth in finishing barrows.

Environmental impacts of livestock systems, especially pig production, have come under increasing debate in recent years. The challenge is in meeting the growing demand for food at an affordable cost, without compromising environmental integrity. Previous studies have shown that feed production is responsible for the majority of CO₂-eq. emission resulting from pig farming systems. This seems to indicate that feed strategies could be an effective tool to achieve the sustainability of the pork chain. Therefore, dietary crude protein reduction, through the addition of industrial amino acids, lessens the nitrogen excretion by pigs and, consequently, could mitigate the effects on the environment of pig production. In this sense, to effectively evaluate the environmental impacts of pig production systems, life cycle assessment has been widely used in agriculture, but the effects of feed are still understudied in Brazilian conditions. Owing to the importance and the great concern in this research area, we presented in this paper an updated review focusing on the nutritional techniques and their potential to reduce the global warming potential of pig production, considering both the direct effects, related to the choice of feed ingredients and the indirect effects, related to changes in the efficiency of use of nutrient by the animals.

SUMMARY The objective of this study was to determine the chemical composition, apparent metabolizable energy (AME), apparent metabolizable energy corrected for nitrogen balance (AMEn) and the metabolizability of dry matter (DM), crude protein (CP), ether extract (EE) and neutral detergent fiber (NDF) of passion fruit seed meal (PFM) for quails. One hundred meat quails (Coturnix coturnix japonica), with 21 days old, allotted in a completely randomized design, with four treatments, five replicates and four animals per experimental unit. The treatments consisted of different levels PFM (4.0, 8.0, 12.0 and 16.0%) that replaced the basal diet (w/w). Metabolizable values were determined by fitting linear equations the PFM can be characterized as an alternative feedstuff for meat quails and the main chemical compounds are gross energy (5,569 kcal kg-1), CP (11.34%), EE (18.84%) and NDF (50.22%), as fed basis. Linear equations were fitted as follow: AME = 2,976 x + 5.877 (r2 = 0.94) and AMEn = 2,939 x + 4.864 (r2 = 0.95), thus AME and AMEn were estimated at 2,976 and 2,939 kcal kg-1, respectively. Additionaly, equations were adjusted for CP, EE, NFD and DM, respectively resulting in a metabolization of 6.35, 17.9, 12.48 and 45.66%. It is concluded that main components of the passion fruit seed meal are gross energy, crude protein, ether extract and neutral detergent fiber and its AME and AMEn for meat quails are 2,976 and 2,939 kcal kg-1, respectively.

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.

This study was conducted to determine the optimum dietary glycine equivalent (Gly_equi) level in low-crude-protein diets of 181 g·kg⁻¹ containing varied concentrations of standardized ileal digestible (SID) methionine + cysteine (Met + Cys) for broiler chicks (1–21 d old). A total of 1275, 1-d-old Cobb-Vantress^® male broilers were distributed in a 5 × 3 factorial arrangement with a completely randomized design of 15 treatments with five replicates of 17 birds each. Treatments consisted of five levels of dietary Gly_equi (14.9, 16.4, 17.9, 19.4, and 20.6 g·kg⁻¹) and three concentrations of SID Met + Cys (7.70, 9.0, and 10.3 g·kg⁻¹). Interactions between Gly_equi and SID Met + Cys levels were observed for feed:gain (P = 0.055) and breast meat yield (BMY) (P = 0.017). In 7.7 and 9.0 g SID Met + Cys·kg⁻¹ diets, optimal feed:gain and increased BMY were observed at Gly_equi levels not lower than 17.9 g·kg⁻¹. In 10.3 g SID Met + Cys·kg⁻¹ diet, a lower feed:gain was achieved at 19.4 g Gly_equi·kg⁻¹. Therefore, a minimum dietary level of 17.9 g Gly_equi·kg⁻¹ is needed to increase growth of broilers fed diets containing 7.7 or 9.0 g·kg⁻¹ SID Met + Cys, whereas 19.4 g·kg⁻¹ Gly_equi is necessary in diets containing 10.3 g·kg⁻¹ SID Met + Cys for optimum growth.