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Manejo da adubação nitrogenada em capim-marandu sob pastejo: respostas da planta e do animal e dinâmica de carbono e nitrogênio no solo

2026-06-12T23:00:06Z

Título: Manejo da adubação nitrogenada em capim-marandu sob pastejo: respostas da planta e do animal e dinâmica de carbono e nitrogênio no solo Autor(es): Freitas, Roberta Santos de Abstract: Approximately 50 to 70 percent of Brazilian pastures are in a state of degradation, which requires technological alternatives to improve forage quality and productivity. This study aimed to evaluate the effects of different nitrogen sources and application strategies on the agronomic characteristics of Marandu grass, cattle performance, and soil carbon (C) and nitrogen (N) stocks. The experiment was conducted at Tocantins Federal University (UFT) over two experimental years (2022-2023), with an 84-day experimental period per year, divided into three 28-day cycles. Urea (UR) and ammonium nitrate + calcium (NA) were tested under two application methods, single application (AU) and split applications (AP), in a 2×2 factorial design with three replicates. In the first year, 150 kg N ha⁻¹ was applied, and in the second year, 75 kg N ha⁻¹. Male cattle were used, with an average weight of 349.26 kg in the first year and 287.17 kg in the second year, distributed across 12 experimental paddocks of 0.33 ha each, with two animals per paddock. Animal performance was evaluated by weighing at each cycle, and forage samples were collected for agronomic and chemical and bromatological analyses. Litter was collected and analyzed for biomass, total nitrogen, organic matter (OM), and total carbon (TC). Carbon and nitrogen assessments were performed to estimate the soil C and N stocks by dry combustion. The use of NA fertilizer resulted in greater plant height (41.53 cm), higher organic matter content (923.6 g kg⁻¹), and litter carbon (567.01 g kg⁻¹) in the second year, compared to urea (34.85 cm; 877.40 and 545.71 g kg⁻¹, respectively). In the first year, the URAU fertilization reduced the crude protein content of the forage from 13% to 8%. In the second year, urea promoted higher leaf production in the first cycle but reduced it in the following cycles. Split fertilizer application resulted in a higher leaf blade/stem ratio in both years and greater animal productivity gains in the first year (TPG = 66.25 kg animal⁻¹; ADG = 0.789 kg animal⁻¹; TPA = 401.52 kg ha⁻¹; CY = 13.38 @ ha⁻¹). The use of NA resulted in higher C stocks up to 40 cm (32.82 and 20.61 Mg ha⁻¹) and higher N stocks in the 0–20 cm layer (2.02 Mg ha⁻¹), while split fertilization increased nitrogen content and stock in the 60–80 and 80–100 cm layers (0.600 and 0.370 Mg ha⁻¹, respectively). The use of NA as a nitrogen fertilizer increases the proportion of leaves with higher crude protein content and enhances soil C and N stocks in the upper layers. Split nitrogen fertilization, regardless of fertilizer source, is a promising management strategy, as it improves animal productivity, forage and litter quality, and nitrogen stocks in deeper soil layers. Tipo: Tese

Respostas termofisiológicas e reprodutivas de carneiros deslanados submetidos a estresse térmico moderado induzido por insulação escrotal

2026-06-08T22:56:08Z

Título: Respostas termofisiológicas e reprodutivas de carneiros deslanados submetidos a estresse térmico moderado induzido por insulação escrotal Autor(es): Araújo, Alan Martins de Abstract: This study investigated the effects of heat stress on thermoregulatory and reproductive responses in hair sheep, using scrotal insulation as an experimental model. Seven adult rams were subjected to scrotal insulation for seven consecutive days in a longitudinal design consisting of pre-insulation (4 weeks), insulation (1 week), and post-insulation (9 weeks). Four semen collections were performed during the pre-insulation phase and nine during the post-insulation phase, with continuous environmental monitoring. During insulation, thermophysiological parameters were recorded after 24 h (D2) and 96 h (D4). Semen was evaluated for sperm kinetics by CASA, concentration, morphology, DNA integrity, and binding pattern of Ram Seminal Vesicle Proteins (RSVPs) by immunocytochemistry. Reproductive variables were analyzed using the Friedman test, while individual thermotolerance was determined by principal component analysis (PCA), with group comparisons performed using the Kruskal–Wallis test. The maximum recorded temperature was 35.1 °C and the minimum was 25.8 °C. Relative humidity ranged from 84.1% to 45.0%. Scrotal insulation increased scrotal surface temperature by 0.75 °C and epididymal tail temperature by 0.90 °C compared with pre-insulation values (33.25 °C and 31.75 °C), without changes in rectal or ocular temperature. Thermal gradients decreased during insulation, from 3.00 °C to 1.96 °C (ocular–scrotal) and from 7.35 °C to 6.01 °C (rectal–epididymal), with recovery after insulation removal. Total motility decreased (p < 0.05) from 85.2 ± 2.2% to 40.6 ± 13.6% in the second post-insulation week, reaching 23.4 ± 10.4% in the fourth week, with recovery by the sixth week (67.7 ± 6.2%; p > 0.05). Progressive motility declined from 80.4 ± 2.5% to 38.3 ± 13.2% and 19.2 ± 8.9%, returning to 59.1 ± 6.9% in the sixth week. Scrotal circumference varied from 30.3 ± 0.7 cm (pre-insulation) to 31.4 ± 0.6 cm (p > 0.05) and decreased to 28.6 ± 0.5 cm in the third week (p < 0.05). Normal morphology dropped from 89.9 ± 4.2% to 39.7 ± 13.2% in the third week, recovering to 75.8 ± 5.6% in the seventh week (p > 0.05), while major defects increased from 4.9 ± 2.3% to 53.9 ± 9.9% in the fifth week. DNA integrity decreased from 92.9 ± 1.5% to 78.1 ± 1.7%, reaching 24.1 ± 9.8% in the fourth week, with recovery to 88.1 ± 1.4% in the seventh week. RSVP binding intensity declined from 3.8 ± 0.7 × 10⁶ AU to 0.7 ± 0.2 × 10⁶ AU, normalizing by the seventh week. PCA distinguished low- and high-thermotolerance groups, with HTT animals showing higher (p < 0.05) total motility (73.6 ± 2.7% vs. 62.2 ± 4.7%), progressive motility (68.2 ± 2.9% vs. 58.7 ± 4.5%), concentration (3.2 ± 0.07 × 10⁹ vs. 2.8 ± 0.1 × 10⁹ sperm/mL), and DNA integrity (81.2 ± 2.6% vs. 70.2 ± 4.4%). In conclusion, seven days of scrotal insulation impair thermoregulation and induce reproductive losses, with heterogeneous responses among animals, highlighting interindividual variability under heat stress. Tipo: Dissertação

Criação e manejo de Xylocopa frontalis e sua utilização comparativa na polinização do urucuzeiro (Bixa orellana)

2026-05-29T19:54:37Z

Título: Criação e manejo de Xylocopa frontalis e sua utilização comparativa na polinização do urucuzeiro (Bixa orellana) Autor(es): Silva, Felipe Jackson de Farias Abstract: We aimed to propose improvements to a rational nest model for bees of the genus Xylocopa, especially X. frontalis, as well as techniques for the rearing, multiplication, and management of this species, and its efficiency as a pollinator of the annatto tree (Bixa orellana), compared to three other native bee species (Augochloropsis sp., Melipona fasciculata, and Melipona flavolineata). The first colonized nests appeared few months after their installation in the study area. The number of galleries built per nest ranged from one to six (3.82 ± 1.4). The galleries had a total average length of 104.19 (±43.41) cm and an excavated volume of 327.15 (±136.29) cm³. Active nests were observed throughout the study period and were transported and relocated without abandonment. Regarding pollination, peak flower visits occured between 7:00 and 8:00 AM, with X. frontalis foraging earlier than other bees and making shorter flower visits. No statistically significant differences were detected in any fruit parameters between treatments. The treatment with free pollination showed the highest fruit set rate (37.5%), followed by a visit from M. flavolineata (25%), although no statistically significant difference was observed. We conclude that our rational nesting device is a suitable alternative for the rearing and management of Xylocopa frontalis and, presumably, other species of the genus for crop pollination or research purposes, without evidence of negative interference in the nesting biology of these bees. Xylocopa frontalis proved to be an efficient pollinator of Bixa orellana. Tipo: Tese

Ácidos orgânicos e suas associações com prebiótico ou extrato vegetal na alimentação de poedeiras comerciais leves

2026-05-13T23:19:55Z

Título: Ácidos orgânicos e suas associações com prebiótico ou extrato vegetal na alimentação de poedeiras comerciais leves Autor(es): Mariano, Lidia Sarah Dias Abstract: The aim of this study was to evaluate the effects of adding combinations of organic acids, or organic acids combined with a prebiotic or plant extract, to the diet of commercial laying hens between 40 and 70 weeks of age. A total of 384 NOVOgen White laying hens were distributed in a completely randomized design with eight treatments and six replicates of eight birds per experimental unit. The treatments were as follows: T1 (negative control) – diet without growth promoter; T2 (positive control) – diet with growth promoter (0.05 g/kg of Halquinol); T3 – 1.81 g/kg of formic acid + 0.44 g/kg of propionic acid; T4 – 3.62 g/kg of formic acid + 0.88 g/kg of propionic acid; T5 – 1.10 g/kg of formic acid + 0.66 g/kg of propionic acid + 0.86 g/kg of butyric acid + 0.72 g/kg of prebiotic; T6 – 1.65 g/kg of formic acid + 1.0 g/kg of propionic acid + 1.30 g/kg of butyric acid + 1.08 g/kg of prebiotic; T7 – 1.58 g/kg of formic acid + 0.30 g/kg of propionic acid + 0.10 g/kg of plant extract; and T8 – 3.16 g/kg of formic acid + 0.60 g/kg of propionic acid + 0.20 g/kg of plant extract. The prebiotic used was inulin-based, and the plant extract consisted of oregano essential oil. The variables evaluated included productive performance, external and internal egg quality, lipid stability of fresh and stored egg yolks (TBARS), antioxidant potential of fresh and stored eggs (phenolic compounds, DPPH, and ABTS), lipid stability of the liver and reproductive organs (TBARS), and bone quality. A significant effect of treatments was observed only for yolk color, with increased yolk color intensity in hens receiving the mixture of organic acids associated with plant extract at the 0.10 % inclusion level. It can be concluded that the addition of organic acids and their associations with prebiotic or plant extract at the evaluated levels did not influence productive performance, external and internal egg quality, yolk lipid stability, egg antioxidant potential, lipid stability of the liver and reproductive organs, or bone quality of laying hens. Tipo: Dissertação