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dissertação
Influência do tamanho de grupo sobre o comportamento e desempenho produtivo de touros nelore confinados no período chuvoso
(Universidade Federal de Lavras, 2026-07-20) Bonamichi Junior, Valter; Bernardes, Thiago Fernandes; Orientador; Benez, Fernanda Macitelli; Maia, Alex Sandro Campos; Benez, Fernanda Macitelli; dc.contributor.referee1; dc.contributor.referee2; dc.contributor.referee3; dc.contributor.referee4; dc.contributor.referee5
In order to increase productivity, there is a global trend toward reducing the space allowance per animal in feedlot systems, which can negatively affect welfare, especially during the rainy season, due to the accumulation of manure and mud in the pens. Given this, the objective of the present study was to evaluate whether reducing group size and increasing space availability improves animal welfare and, consequently, the performance of feedlot cattle during the rainy season. A total of 1,125 Nellore bulls, aged 24 ± 4 months and with an initial body weight (BW) of 395 ± 18.7 kg, were used in a completely randomized design with the following treatments: i) pen with 50 animals (B50), ii) pen with 75 animals (B75), and iii) pen with 100 animals (B100). Thus, in treatments B50, B75, and B100, each animal had 30 m² of usable area, 100 cm of feed bunk, and 4.8 cm of linear waterer space; 20 s m² of usable area, 67 cm of feed bunk, and 3.2 cm of linear waterer space; and 15 m² of usable area, 50 cm of feed bunk, and 2.4 cm of linear waterer space, respectively. All animals received the same diet during the 81 day experimental period. Animal welfare indicators based on the environment (mud depth) and on the animals themselves were used, such as behavioral indicators (number of animals standing, lying down, at the feed bunk, or at the waterer; and incidence of fighting, head-butting, and mounting attempts), comfort (dirtiness score of the animals), and health (coughing and sneezing frequency, percentages of animals with diarrhea, lameness, and nasal and ocular discharge). Performance indicators (dry matter intake (DMI), final weight, average daily gain (ADG), and feed efficiency) and carcass characteristics (hot carcass weight, dressing percentage, total carcass production, trimming percentage, and carcass losses) were also evaluated. In general, the results showed that B50 provided better environmental and social conditions, as evidenced by lower mud depth (P < 0.05), lower percentages of dirty animals (P < 0.0001), and a lower incidence of agonistic behavior among individuals (P < 0.05). Group size did not affect the percentage of animals lying down, standing, or feeding (P > 0.05), nor did it influence overall growth performance (P > 0.05). Differences were observed only for dry matter intake (DMI) (P < 0.001) and total carcass production (TCP) (P < 0.001), where the B50 treatment resulted in the highest DMI, and B100 resulted in the highest TCP compared to the other treatments. In conclusion, for regions with low rainfall during the confinement period (around 472 mm) and a total area per bay of 1,500 m² , it is recommended to adopt 100 animals per group, as the reduction did not affect the animals’ performance.
dissertação
Efeito do inóculo misto de Kluyveromyces lactis e Lactiplantibacillus plantarum na produção de queijo maturado
(Universidade Federal de Lavras, 2025-02-28) Paula, Francielle Louise Jesus de; Duarte, Whasley Ferreira; Piccoli, Roberta Hilsdord; Andrade, Rafaela Pereira
Cheese ripening is a complex process, dependent on metabolic activity and on the interactions established among microorganisms present in the dairy matrix, which directly influence the physicochemical, microbiological, and sensory characteristics of the final product. In this context, the use of mixed starter cultures constitutes a promising biotechnological strategy to modulate ripening and to confer unique technological attributes to cheeses. The present study aimed to evaluate the effect of co-inoculation of the yeast Kluyveromyces lactis (B10) and the lactic acid bacterium Lactiplantibacillus plantarum (BP16), isolated from the ecosystem of Minas Artesanal cheese, on the production of ripened cheese over 28 days. For this purpose, cheeses were produced from pasteurized milk and distributed into two treatments: a control treatment, containing a commercial bacterial starter culture associated with K. lactis, and an experimental treatment, containing a mixed inoculum of K. lactis and L. plantarum. During ripening, the cheeses were evaluated for microbial population dynamics, carbohydrate and organic acid composition, texture profile, microstructure, volatile compound profile, and antioxidant activity. Co-inoculation promoted more intense ripening, resulting in cheeses with greater softness, higher antioxidant activity, and a more complex aromatic profile compared to the control treatment. It was possible to observe a predominantly antagonistic interaction between the microorganisms, with metabolic predominance of L. plantarum throughout ripening. Thus, it was concluded that the association of K. lactis and L. plantarum shows potential for application as a mixed starter culture in the production of ripened cheeses, contributing to the optimization of ripening and to the improvement of the sensory characteristics of the product.
tese
Fatores nutricionais e comportamentais associados à dinâmica do pH ruminal em vacas leiteiras
(Universidade Federal de Lavras, 2026-03-26) Rezende, João Pedro Andrade; Danés, Marina de Arruda Camargo; Pereira, Marcos Neves; Rotta, Polyana Pizzi; Daniel, João Luiz Pratti; Carneiro, Jorge Henrique
This work aimed to integrate different approaches to investigate the occurrence of subacute ruminal acidosis in dairy cows, as well as feeding behavior and nutritional and/or monitoring strategies for its prevention, with potential implications for productivity and animal health in dairy systems. To achieve this, three complementary studies were conducted, combining controlled experimentation, integration of experimental datasets, and evaluation under commercial conditions. In the first study, magnesium phosphate (MgP) was evaluated as a source of magnesium and phosphorus for lactating dairy cows. Supplementation with MgP, either alone or in combination with magnesium oxide, did not affect dry matter intake, milk yield, or ruminal pH and fermentation variables. However, increased dietary magnesium supply increased milk fat concentration, which was associated with greater proportions of preformed fatty acids and higher ether extract digestibility, as well as improved total-tract nutrient digestibility. In the second study, associations among carbohydrate intake, feeding behavior, and ruminal pH dynamics were evaluated using integrated data from two experiments with continuous ruminal pH measurement via bolus sensors. Fiber intake, particularly forage NDF and physically effective NDF relative to body weight, was positively associated with rumination and chewing time and with indicators of greater ruminal pH stability. Rumination modified the relationship between fiber intake and ruminal pH, whereas parity effects indicated greater responsiveness in multiparous cows and increased susceptibility of primiparous cows to unfavorable pH conditions. Ruminal pH variables were also associated with productive performance, milk fatty acid profile, and physiological markers. In the third study, the potential of collar-derived rumination time as a tool for nutritional monitoring at the pen level under commercial conditions was evaluated. Rumination time was positively associated with milk yield and dry matter intake and showed strong relationships with diet composition and nutrient intake variables, particularly lignin. These associations were more pronounced in early lactation, and the results indicate that sensor-derived rumination data can serve as useful indicators of nutritional management in commercial dairy systems. Overall, the results demonstrate that ruminal pH dynamics and their relationship with productive performance depend on the interaction among fiber intake, feeding behavior, and animal characteristics, and that sensor-based tools have potential to support nutritional monitoring and decision-making in dairy production systems.
dissertação
Action of papain and chitosan on phytotoxicity and antioxidant system of Phaseolus vulgaris L.
(Universidade Federal de Lavras, 2026-07-28) Langa, Yanick Leontino; Soares, Filippe Elias de Freitas; Ferreira, Cecilia Baldoino; Ferreira, Juliana Marques; Nascimento, Vitor de Laia
The transition toward sustainable agriculture has driven the adoption of bio-inputs derived from secondary metabolites and biopolymers as alternatives to synthetic agrochemicals. However, the application of these molecules requires a thorough understanding of the boundaries between biostimulation and phytotoxicity, as well as the energetic costs associated with the activation of plant defense mechanisms. This study evaluated the morpho-agronomic responses and antioxidant biochemical profile of Phaseolus vulgaris L. subjected to papain and chitosan treatments. Initially, a critical review was conducted on the thresholds between eustress and distress in plant physiology under the use of elicitors. Subsequently, the non-target effects of increasing papain concentrations (0 to 16%) applied via soil drench and foliar spray were investigated. The results revealed a delivery route-dependent paradox: foliar application induced acute oxidative stress, with a dose-dependent increase in malondialdehyde (MDA), accompanied by marked activation of guaiacol peroxidase (GuPOX) and phenolic compounds, whereas soil application maintained plant homeostasis due to rhizosphere buffering. Composite Z-Score modeling identified the 2% foliar treatment as the optimal operational dose. Finally, rhizosphere applications of papain (4%), chitosan (2%), and their combination (P+Q) were evaluated. Papain applied alone acted as a phytotoxic stressor, whereas chitosan reduced pod production due to energetic trade-offs. However, the combined application (P+Q) produced a synergistic hormetic effect, in which chitosan mitigated papain-induced toxicity and restored agronomic performance. These findings demonstrate that the biotechnological success of these bio-inputs depends on the precise optimization of dose, molecular combinations, and delivery route.
dissertação
Valorização de resíduos têxteis e madeira na produção de compósitos sustentáveis
(Universidade Federal de Lavras, 2026-05-27) Terra, Renata Costa; Mendes, Lourival Marin; Guimarães Júnior, José Benedito; Oliveira, Bárbara Maria Ribeiro Guimarães de; Silva, Cínthia Aparecida
The growing demand for sustainable materials has driven the development of composites with lower environmental impact, prioritizing the efficient use of resources and waste reduction. In this context, plant fibers and lignocellulosic materials stand out as promising alternatives to synthetic reinforcements due to their wide availability, low cost, biodegradability, and satisfactory mechanical properties. At the same time, the significant increase in textile waste generation and its inadequate disposal have intensified environmental impacts, highlighting the need for strategies that promote its reuse. In this scenario, the present study proposes the production of sustainable composites (particleboards) through the incorporation of shredded textile waste (STW) and wood particles (Pine), using a bio-based polyurethane resin. The experimental design was structured with different proportions of STW (0%, 25%, 50%, 75%, and 100%), allowing the evaluation of the influence of waste content on the material properties. The results indicated that increasing the STW fraction promoted changes in the composite microstructure, with increased porosity and void content. Although density remained stable, higher water absorption and thickness swelling were observed, along with a reduction in mechanical properties at higher waste contents. Thermal conductivity did not show significant variations among treatments, maintaining the insulating characteristics of the composites. On the other hand, the increased porosity contributed to improved acoustic performance, highlighting the potential of these materials for non-structural applications, especially as thermal and acoustic insulating materials. Therefore, the study demonstrates the feasibility of reusing textile waste in the production of sustainable materials aligned with the principles of the circular economy.