RESUMO

The nutritional composition of bovine liver, particularly in terms of vitamins E, ß-carotene, and cholesterol concentration, is significantly influenced by the cattle-rearing system and diet. This study aimed to elucidate the impact of four predominant cattle-rearing systems in the Eastern Amazon region on the vitamin E, ß-carotene content, and cholesterol levels in bovine liver during the rainy season. Liver-tissue samples were collected from 48 cattle, with twelve specimens representing each rearing system. The systems encompassed two native pastures located in flood-prone areas, cultivated pastures on upland terrain and a confinement-rearing system. Our findings indicate that, when considering all rearing systems collectively, there were no significant differences in the levels of vitamins and cholesterol in the liver tissues (p > 0.05). However, a marked disparity in cholesterol levels emerged when comparing intensive rearing systems to extensive ones, with the former demonstrating notably higher concentrations (p = 0.01). Additionally, the intensive rearing system was associated with elevated levels of ß-carotene (p < 0.01), α-tocopherol (p = 0.01), and ß-tocopherol (p = 0.01) relative to the extensive systems. No significant variations were observed amongst the different extensive systems (p > 0.05). These results suggest that, while all rearing systems yielded liver tissues with typical concentrations of vitamins and cholesterol, the intensive rearing system led to a higher accumulation of certain vitamin compounds. This study highlights the substantial nutritional implications of different cattle-rearing systems in the Eastern Amazon and provides valuable insights for developing dietary strategies to optimize the nutritional quality of bovine liver. Therefore, the generated results are groundbreaking in the Eastern Amazon, Brazil, and inspire the development of new research projects to address other demands in this field and achieve additional outcomes.

RESUMO

Introduction: The quality of meat, with a focus on compounds important for human health, is directly related to the rearing systems in which the animals are produced. The search for a balanced diet, with an emphasis on low cholesterol and adequate levels of vitamins, aligns with society's emphasis on healthy eating, directly correlated with the importance of the offer made by producers for the cattle's diet. Objective and methodology: The objective was to verify the impact of different rearing systems, in the Eastern Amazon, during the rainy season, on the concentrations of vitamins (A, E) and cholesterol in the muscle (Longissimus lumborum) of crossbred Nelore cattle, castrated, aged between 24 and 36 months, and weighing between 410 and 628 kg. Twelve animals, from each of the three pasture rearing systems: native pasture in flooded areas of Monte Alegre; native pasture in a flooded area of Santa Cruz do Arari; and pasture cultivated on dry land in São Miguel do Guamá, all located in Pará, Brazil-were sampled in commercial slaughterhouses. Results: A notable influence was observed in the concentrations of ß-carotene (p < 0.01), α-Tocopherol (p = 0.02), ß-Tocopherol (p < 0.01) and the combined sum of ß-Tocotrienol and γ-Tocopherol (p < 0.01), as well as δ-Tocopherol (p < 0.01) when contrasting extensive with intensive systems (confinement). However, there was a difference in the content of vitamins and cholesterol between the isolated extensive systems, or between the four rearing systems (p > 0.05). Extensive systems, mainly in Monte Alegre, demonstrated greater amounts of α-Tocopherol and δ-Tocopherol. Conclusion: On the other hand, the intensive system exhibited higher levels of other investigated compounds, clarifying the nutritional variations generated by different livestock rearing practices in the region. Therefore, the results obtained are innovative in the Eastern Amazon, Brazil, in addition to inspiring the development of new research to meet other demands in this field, and achieve additional results, such as determining which meat, coming from cattle in production systems in the country, presents the better compositional quality of vitamins and lipids.

RESUMO

Variability in climatic conditions of low-latitude tropical grass cultivation can affect forage production dynamics. Pasture ecosystems are complex and preferably studied from a multifactorial point of view through multivariate approaches. Therefore, in this study, we characterized different growing conditions for grasses of the Megathyrsus genus through studies conducted in tropical humid and semi-arid conditions. We applied principal component, canonical correlation, and discriminant function analyses to the measurements of agronomic and agrometeorological variables in six studies with Guinea and Massai grasses. The principal component analysis, through the climatic characterization by the first principal component, reflects the contrast between water availability and nitrogen variables and energy supply. Agronomic characterization occurred through the distinction between the density of tillers, forage accumulation, and increase in height, versus the accumulation of stems and dead material. The canonical correlation analysis generated a correlation coefficient of 0.84 between the agronomic and agrometeorological variables. There was a contrast between the dead material accumulation and the other agronomic variables, while the agrometeorological variables showed characteristics similar to the first principal component. Discriminant function 1, with 70.36% separation power, distinguished the cultivation conditions based on the study locations. Grass cultivars were differentiated by discriminant function 2, with a 19.20% separation power. From a multivariate variability analysis, despite the similarities of radiation and temperature in the regions studied, the availability of water and nutrients and measurements of agronomic variables can aid in future modeling studies on forage production.

RESUMO

Abstract The objective of the present study was to evaluate the effect of different frequencies of defoliation at fixed periods on the structural and productive characteristics of Tanzania grass (Panicum maximum) under Am climate conditions in 2014. The experimental design was in complete randomized blocks with six treatments corresponding to six frequencies of defoliation (14, 21, 28, 35, 42, and 49 days) and five repetitions. The data was submitted to regression analysis. The light interception (LI) increased (P 0.05) in an asymptotic way with increasing rest periods. The maximum light interception was 98% and occurred at 42 days of regrowth. The leaf area index (LAI) and the dry matter accumulation increased (P 0.05) linearly varying from 3.6 to 7.1 and from 880.3 to 4051.7 kg.ha-1 of forage dry matter in the frequencies 14-49 days, respectively. The height ranged 44-119 cm at frequencies 14-49 days, respectively. The frequency of defoliation at 95% LI is related to the rest period of 29 days, where the Tanzania grass canopy presented around 63 cm height, critical LAI of 5.1, and forage dry matter accumulation of 2,160 kg ha-1.

Resumo Objetivou-se com este trabalho avaliar o efeito de diferentes frequências de desfolhação em períodos fixos sob as características estruturais e produtivas do dossel de capim-Tanzânia (Panicum maximum Jacq) em condições climáticas Am no ano de 2014. O delineamento experimental foi em blocos casualizados com seis tratamentos correspondentes a seis frequências de desfolhação (14; 21; 28; 35; 42 e 49 dias) e cinco repetições e os dados foram submetidos a análise de regressão. A interceptação luminosa (IL) aumentou (P 0,05) de maneira assintótica com o aumento dos períodos de descanso, no qual a máxima interceptação de luz foi de 98% e ocorreu aos 42 dias de rebrotação. O índice de área foliar (IAF) e o acúmulo de matéria seca, aumentaram (P 0,05) linearmente variando de 3,6 a 7,1 e de 880,3 a 4051,7 kg.ha-1 de matéria seca de forragem, nas frequências de 14 a 49 dias, respectivamente. A altura variou de 44 a 119 cm nas frequências de 14 a 49 dias, respectivamente. A frequência de desfolhação que representa uma IL de 95% está relacionada ao período de descanso de 29 dias, em que o dossel de capim-Tanzânia apresentou altura em torno de 63 cm, IAF crítico de 5,1 e acúmulo de matéria seca de forragem de 2.160 kg.ha-1.

RESUMO

The objective of the present study was to evaluate the effect of different frequencies of defoliation at fixed periods on the structural and productive characteristics of Tanzania grass (Panicum maximum) under Am climate conditions in 2014. The experimental design was in complete randomized blocks with six treatments corresponding to six frequencies of defoliation (14, 21, 28, 35, 42, and 49 days) and five repetitions. The data was submitted to regression analysis. The light interception (LI) increased (P < 0.05) in an asymptotic way with increasing rest periods. The maximum light interception was 98% and occurred at 42 days of regrowth. The leaf area index (LAI) and the dry matter accumulation increased (P < 0.05) linearly varying from 3.6 to 7.1 and from 880.3 to 4051.7 kg.ha-1 of forage dry matter in the frequencies 14-49 days, respectively. The height ranged 44-119 cm at frequencies 14-49 days, respectively. The frequency of defoliation at 95% LI is related to the rest period of 29 days, where the Tanzania grass canopy presented around 63 cm height, critical LAI of 5.1, and forage dry matter accumulation of 2,160 kg ha-1.(AU)

Objetivou-se com este trabalho avaliar o efeito de diferentes frequências de desfolhação em períodos fixos sob as características estruturais e produtivas do dossel de capim-Tanzânia (Panicum maximum Jacq) em condições climáticas Am no ano de 2014. O delineamento experimental foi em blocos causalizados com seis tratamentos correspondentes a seis frequências de desfolhação (14; 21; 28; 35; 42 e 49 dias) e cinco repetições e os dados foram submetidos a análise de regressão. A interceptação luminosa (IL) aumentou (P < 0,05) de maneira assintótica com o aumento dos períodos de descanso, no qual a máxima interceptação de luz foi de 98% e ocorreu aos 42 dias de rebrotação. O índice de área foliar (IAF) e o acúmulo de matéria seca, aumentaram (P < 0,05) linearmente variando de 3,6 a 7,1 e de 880,3 a 4051,7 kg.ha-1 de matéria seca de forragem, nas frequências de 14 a 49 dias, respectivamente. A altura variou de 44 a 119 cm nas frequências de 14 a 49 dias, respectivamente. A frequência de desfolhação que representa uma IL de 95% está relacionada ao período de descanso de 29 dias, em que o dossel de capim-Tanzânia apresentou altura em torno de 63 cm, IAF crítico de 5,1 e acúmulo de matéria seca de forragem de 2.160 kg.ha-1.(AU)

Assuntos

RESUMO

The objective of the present study was to evaluate the effect of different frequencies of defoliation at fixed periods on the structural and productive characteristics of Tanzania grass (Panicum maximum) under Am climate conditions in 2014. The experimental design was in complete randomized blocks with six treatments corresponding to six frequencies of defoliation (14, 21, 28, 35, 42, and 49 days) and five repetitions. The data was submitted to regression analysis. The light interception (LI) increased (P < 0.05) in an asymptotic way with increasing rest periods. The maximum light interception was 98% and occurred at 42 days of regrowth. The leaf area index (LAI) and the dry matter accumulation increased (P < 0.05) linearly varying from 3.6 to 7.1 and from 880.3 to 4051.7 kg.ha-1 of forage dry matter in the frequencies 14-49 days, respectively. The height ranged 44-119 cm at frequencies 14-49 days, respectively. The frequency of defoliation at 95% LI is related to the rest period of 29 days, where the Tanzania grass canopy presented around 63 cm height, critical LAI of 5.1, and forage dry matter accumulation of 2,160 kg ha-1.

Objetivou-se com este trabalho avaliar o efeito de diferentes frequências de desfolhação em períodos fixos sob as características estruturais e produtivas do dossel de capim-Tanzânia (Panicum maximum Jacq) em condições climáticas Am no ano de 2014. O delineamento experimental foi em blocos causalizados com seis tratamentos correspondentes a seis frequências de desfolhação (14; 21; 28; 35; 42 e 49 dias) e cinco repetições e os dados foram submetidos a análise de regressão. A interceptação luminosa (IL) aumentou (P < 0,05) de maneira assintótica com o aumento dos períodos de descanso, no qual a máxima interceptação de luz foi de 98% e ocorreu aos 42 dias de rebrotação. O índice de área foliar (IAF) e o acúmulo de matéria seca, aumentaram (P < 0,05) linearmente variando de 3,6 a 7,1 e de 880,3 a 4051,7 kg.ha-1 de matéria seca de forragem, nas frequências de 14 a 49 dias, respectivamente. A altura variou de 44 a 119 cm nas frequências de 14 a 49 dias, respectivamente. A frequência de desfolhação que representa uma IL de 95% está relacionada ao período de descanso de 29 dias, em que o dossel de capim-Tanzânia apresentou altura em torno de 63 cm, IAF crítico de 5,1 e acúmulo de matéria seca de forragem de 2.160 kg.ha-1.

Assuntos