The scientific literature currently lacks studies that evaluate the nutritional composition of the tissues of cattle raised in different systems, so that the nutritional effects can be known and used to enhance consumption and use in the diet. The aim was therefore to assess whether the mineral content of muscle tissue (longissimus lumborum) in cattle finished during the rainy season in the Eastern Amazon is influenced by different farming systems. The treatments consisted of four systems (three pasture production systems and one feedlot system). 1. native wetland pasture in Santa Cruz do Arari (Mesoregion of Marajó); 2. native wetland pasture in Monte Alegre (Mesoregion of Baixo Amazonas); 3. cultivated dryland pasture in São Miguel do Guamá (Mesoregion of Nordeste Paraense); and 4. Confinement in Santa Izabel do Pará (Metropolitan Region of Belém). The analyses were carried out on samples of the longissimus lumborum muscle tissue of 48 male, castrated, crossbred Nelore cattle, twelve per breeding system, from commercial farms, destined for meat production, finished during the rainiest period of the year (between January and June). In systems 1 and 2, the animals were slaughtered in licensed slaughterhouses; the animals in systems 3 and 4 were slaughtered in commercial slaughterhouses. Food sampling and chemical analysis, soil sample collection and analysis, longissimus lumborum muscle tissue collection, sample preparation and digestion, and inductively coupled plasma optical emission spectrometry were evaluated. The experimental design was completely randomized in a linear model with four rearing systems and one period (rainy). The data was compared using the Statistical Analysis Systems (SAS) program. All analyses were carried out considering a significance level of 0.05. Samples of the diets offered (pasture and concentrate) were also collected. The Amazon systems influenced the macro- and micromineral content in the muscles of cattle (p < 0.05). The interaction between pasture systems vs. confinement showed differences in the minerals calcium (Ca), magnesium (Mg), phosphorus (P), copper (Cu), zinc (Zn), iron (Fe), and manganese (Mn) (p < 0.05). However, there was no difference in the values of sodium (Na), potassium (K), and sulfur (S) between the rearing systems (p > 0.05). By contrast, the cultivated pasture system vs. extensive pasture showed differences in all the elements evaluated (p < 0.05). The rearing systems of the Eastern Amazon influenced the mineral content of beef, which continues to be an excellent source of macro- and microminerals and can compose the human diet.

Bovine liver is a food that is known to be nutritious and easily accessible to consumers. The nutritional quality of this food can be influenced by several factors, such as the rearing system. The objective of this study was to characterize the fatty acid profile in the liver tissue of cattle raised in the Brazilian Eastern Amazon, taking into account the effect of the rearing system and seasonality. Liver tissue samples from cattle raised in native pastures, in flooded areas, in cultivated pastures, in highlands and in a confinement, system was evaluated. The liver tissue from the extensive systems showed ( p < 0.05) a higher proportion of saturated fatty acids (C16:0 and 17:0) and a higher proportion of monounsaturated fatty acids compared with the confinement liver tissue. The sum of polyunsaturated fatty acids was higher for the hepatic tissue of the feedlot system compared with the pasture system; however, the tissue of animals from the pasture system showed much higher percentages of long‐chain PUFA′s such as EPA, DHA, DPA, and their precursor, alpha‐linolenic acid. The information gathered is important for optimizing the production of beef and its offal with desirable nutritional properties for promoting human health.

This study aimed to investigate the relationship between rearing systems and seasonality (rainy and dry seasons) on the fatty acid (FA) composition in cattle. Samples of the Longissimus lumborum muscle were obtained from carcasses of 96 castrated Nelore cattle. The samples were lyophilized, and the FA composition was determined by the direct transesterification method and analyzed by gas chromatography. The rearing systems comprise two native pastures (extensive grazing), one cultivated pasture (intensive grazing) and one feedlot. Data were analyzed using generalized linear models, including the fixed effects of production system, season, and their interaction. Regarding polyunsaturated fatty acids (PUFAs), linoleic acid (C18:2n‐6), arachidonic acid (C20:4n‐6), and α‐linolenic acid (C18:3n‐3) were the most abundant in all systems. C18:2n‐6, C18:3n‐3, and C20:4n‐6 were higher in pasture systems than in the feedlot, especially in intensive grazing during the rainy season. In the dry season, the scenario was reversed; C18:2n‐6 and C20:4n‐6 showed a higher concentration in the feedlot system compared to pasture systems. The study demonstrated that pasture production, such as traditional extensive systems, promoted a better ratio of n‐6/n‐3, contributing to a healthier lipid composition in the meat, when compared to the feedlot. Although the feedlot system has a lower concentration of saturated fatty acids (SFAs), the analysis shows that the extensive system offers a more balanced and healthy FA composition.