Zootecnia
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Item Effect of using dried distillery grains in the supplementation of pregnant beef cows on grazing systems and the association of brix degree with blood metabolites in beef calves(Universidade Federal de Viçosa, 2025-02-25) Albuquerque, Jean Marcelo; Lopes, Sidnei Antônio; http://lattes.cnpq.br/4320231116335918In Chapter 1, the objective was to evaluate the effects of prepartum DDG supplementation on the performance, nutritional, and metabolic characteristics of beef cows grazing on low-quality tropical pasture during the peripartum period. Forty- four multiparous Nellore beef cows with an average body weight (BW), body condition score (BCS), and gestation length of 534±43.39 kg, 5.4±0.6 points, and 200 days, respectively, were supplemented with a mineral mixture or with low-intake concentrate supplements (1 kg/animal/day) containing corn and soybean meal-based ingredients or DDG-based ingredients. Supplementation promoted an increase in CP intake and digestibility (P<0.05); however, there was no effect on the intake of the other variables studied (P>0.05). A positive variation in prepartum BCS was observed (P<0.05); nevertheless, no effect was observed on postpartum BCS variation (P>0.05). Concentrations of Beta-hydroxybutyrate and Insulin-like growth factor 1 were lower in cows supplemented during the prepartum period (P<0.05). Under tropical conditions, DDG supplementation yielded results similar to those supplemented with CM+SM, ensuring a better prepartum energy balance. However, prepartum concentrate supplementation did not influence postpartum effects compared to cows that consumed only the mineral mixture. For Chapter 2, the objective was to quantify the relationship between blood serum Brix, serum globulin concentrations, calf performance at 60 days of age, and maternal milk yield in Nellore cattle. The data used in this study were derived from three studies evaluating supplementation in the last third of gestation and its effects on the peripartum and offspring, conducted between 2022 and 2024, totaling 118 treatment means. There was a strong positive correlation (r = 0.842; P < 0.001) between globulin concentration and serum Brix. Regression analysis demonstrated a positive linear relationship between globulin concentrations and serum Brix. For every 1 g/dL increase in globulin concentrations, there is a 0.08% increase in Brix. For every 1% increase in serum Brix, there is an increase of 0.05 kg/day and 3.38 kg in weight at 60 days. It is estimated that for every 1 kg increase in average daily milk yield, there is an increase of 4.8 kg in calf body weight at 60 days, 0.064 kg/day, and an impact of 0.24% on calf serum Brix. Blood serum Brix in Nellore calves has a strong relationship with globulin concentration, serving as a strong indicator of passive immunity transfer. Furthermore, cow milk yield explains a significant portion of calf performance up to 60 days of age. Keywords: zebu; metabolites; peripartum; nutrition; performance ; globulinsItem Voluntary intake of lactanting beef cows during pregnancy under tropical pasture and effects of DDG or sugar cane molasses on performance of calves and heifers respectively(Universidade Federal de Viçosa, 2024-08-13) Matos, Ellem Maria de Almeida; Valadares Filho, Sebastião de Campos; http://lattes.cnpq.br/8610059005070904Our objectives in the current study were: 1) to understand the voluntary intake of beef cows during gestation under grazing in tropical pastures; 2) to evaluate the effects of DDG supplementation on performance and digestion characteristics of suckling beef calves on tropical pastures and 3) to evaluate whether the inclusion of molasses affect voluntary intake, performance, digestive characteristics, and rumen epithelium cell development in young beef finishing heifers. For the first objective, thirty-seven multiparous Nellore cows, along their respective calves, with an average initial body weight (BW) of 517 ±15.7 kg and initial body condition score (BCS) of 5.0, were used. All cows were randomly assigned into eight paddocks with approximately 7.0 ha each, covered evenly with Urochloa decumbens signal grass. Intake and digestibility trials were carried out at approximately 4 days before the insemination (this time point was considered day 0 of gestation) and, 30, 60, 90, 120, 150, 180, 210, 240, and 270 days of gestation. Fecal output was estimated using chromic oxide (Cr2O3) as an external marker. We detected a quadratic pattern (P < 0.05) between week of pregnancy (WP) and dry matter intake (DMI, g/kg BW).In conclusion, the voluntary intake can be adequately described as a function of the week of pregnancy according to the following model: DMI = 20.978±0.9059 + 0.316±0.0947 × WP – 0.0134±0.0023 × WP2 For the second objective, thirty-seven Red Angus × Nellore male calves (162±4.1 kg BW; 120 days old) were used in this study. Cow-calf pairs were randomly assigned into eight paddocks with approximately 7.0 ha each. Four treatments were evaluated, as follows: control (mineral mixture only; n=8), supplement without DDG (n=10), or supplements including 375 (n = 9) and 750 (n = 10) g/kg DDG on a dry matter (DM) basis. The supplements were composed by ground corn, soybean meal, urea, and DDG, and formulated to contain 300 g CP/kg DM. Performance characteristics were evaluated by recording calves’ BW at the beginning and end of the experiment without prior fasting. The ADG and FBW decreased (P = 0.04) linearly as the level of inclusion of DDG in the supplement increased. In conclusion, including 375 or 750 g DDG/kg DM in supplements decreases performance suckling beef calves in tropical pastures. For the third objective, twelve newly weaned Red Angus × Nellore heifers, averaging 238±5.14 kg, were used. The basal diet consisted of corn silage, sorghum silage, ground corn, soybean meal, urea, and mineral mixture, with a forage-to-concentrate ratio of 50:50. The following treatments were evaluated: control (no addition of powdered molasses) or addition of 50 g/kg of diet (DM basis) of powdered molasses. On day 55 of the experiment, a digestibility carried out over a period of 5 days. Briefly, feces samples were collected immediately after defecation on days 1, 2, 3, 4, and 5 of the trial, respectively and on days 3 and 5 of the digestibility trial, urine samples were collected. All heifers were weighed at the beginning and end of the experiment after 16-hour solids fasting. Subsequently, the heifers were slaughtered. There was no effect (P = 0.15) of molasses inclusion in either intake variables or fatty acids concentration. Providing sugarcane molasses does not affect the intake, digestion characteristics, and performance of young beef finishing heifers fed with medium-quality diets. Keywords: beef cattle; by-products; digestion; forage intake.Item Efeito do creep-feeding no estresse e imunidade ao desmame de bezerras Nelore em pastejo(Universidade Federal de Viçosa, 2025-02-25) Lessa, Rafaela Oliveira; Rennó, Luciana Navajas; http://lattes.cnpq.br/9578861445354610O desmame é um evento estressante para bezerros de corte, envolvendo múltiplos fatores que impactam seu desempenho e bem-estar. A suplementação pode influenciar a resposta ao estresse nesse período, tornando-se uma estratégia relevante para minimizar seus efeitos negativos. Assim, o objetivo desse estudo foi avaliar a influência do creep-feeding no estresse e imunidade ao desmame de bezerras Nelore em pastejo. Foram conduzidos quatro experimentos em diferentes anos (2017, 2020, 2023 e 2024), realizados na Unidade de Ensino, Pesquisa e Extensão em Bovinocultura de Corte, do Departamento de Zootecnia/UFV. Foram utilizadas 15 bezerras em 2017, 14 em 2020, 13 em 2023 e 19 em 2024, divididas aleatoriamente em suplementadas (CS) e não suplementadas (SS), sendo todas lactentes com idades e pesos médios iniciais de ± 7,5 meses e 222 ± 32 kg, respectivamente, com suas mães. O período experimental compreendeu os períodos pré-desmame, desmame e pós-desmame. Considerando o desmame como o dia zero, as bezerras foram pesadas (sem jejum) nos dias -5 (pré-desmame), d 0 (5 horas após a separação), d 1, d 3, d 7, d 14 (pós-desmame) às 8h. Simultaneamente foram realizadas coletas de sangue. Foram quantificadas as concentrações de cortisol, ceruloplasmina, haptoglobina, glicose, proteínas totais, albumina, globulinas e as análises hematológicas de contagem de células vermelhas, hematócrito, concentração de hemoglobina e contagem de leucócitos, linfócitos (L), neutrófilos (N) e a relação N:L. Os dados foram analisados utilizando-se o SAS 9.4, adotando-se a=0,05 como nível crítico de probabilidade de ocorrência do erro tipo I. A suplementação pré-desmame e os dias relativos ao desmame afetaram o peso das bezerras (p<0,05), de forma que as bezerras CS apresentaram maior peso em todos os dias avaliados. As concentrações de cortisol, ceruloplasmina, haptoglobina, glicose e albumina variaram ao longo do tempo (p<0,05), mas sem efeito da suplementação (p>0,05). Ocorreu interação suplementação e dias relativos ao desmame para globulinas e contagem de eritrócitos (p<0,05). Entretanto, ao desdobrar a interação, não apresentou diferença significativa entre tratamentos. O hematócrito e a concentração de hemoglobina apresentaram interação entre suplementação e dias relativos ao desmame (p<0,05), e a contagem de leucócitos, linfócitos, neutrófilos e a relação N/L foram afetadas pelos dias relativos ao desmame (p<0,05), sem impacto da suplementação. O creep-feeding não minimiza a magnitude do estresse ao desmame, e o período de maior estresse é nos primeiros três dias pós-desmame, além disso, não influencia a imunidade das bezerras Nelore em pastejo. Palavras-chave: bezerros de corte; cortisol; ganho de peso; hemograma; proteínas de fase agudaItem Avanços da nutrição sobre o desempenho, composição e rendimento de carcaça de frangos de corte(Universidade Federal de Viçosa, 2024-02-27) Monteiro, Filipe Antônio; Hannas, Melissa Izabel; http://lattes.cnpq.br/5010988423506144Este estudo teve como objetivo avaliar o impacto dos avanços nutricionais nas últimas 4 décadas sobre o desempenho, composição corporal e rendimento de carcaça e cortes de frangos de corte machos e fêmeas da linhagem Cobb500® e viabilidade econômica. 1600 frangos de corte foram distribuídos em um delineamento interiamente casualizado com 4 planos nutricionais e 2 sexos, com 10 repetições e 20 aves por unidade experimental. Os planos nutricionais consistiram nas recomendações: Tabelas Brasileiras para Aves e Suínos 2024 para machos (TB 2024M) e fêmeas (TB 2024F), Tabelas Brasileiras para Aves e Suínos 2017 para machos (TB 2017M) e fêmeas (TB 2017F), Tabelas Brasileiras para Aves e Suínos 1983 para machos e fêmeas (TB 1983) e do Guia de Manejo de Frangos de Corte Cobb500 para machos e fêmeas (COBB 2022). O período experimental foi de 42 dias, durante os quais foram avaliados o ganho de peso (GP), consumo de ração (CR), conversão alimentar (CA), composição corporal aos 28 e 42 dias de idade e rendimento de carcaça e cortes. A atualização dos planos nutricionais influenciou os parâmetros de desempenho dos frangos de corte, a composição corporal, e os rendimentos de carcaça e de cortes. Observou-se interação (P<0,05) entre os planos nutricionais e o sexo dos frangos de corte para os parâmetros de desempenho (GP, CR e CA), a composição corporal aos 28 dias (peso corporal, massa magra, proteína e água) e o rendimento de carcaça (peso da coxa e rendimento da coxa). Efeitos independentes do sexo (P<0,05) foram observados para a massa óssea corporal aos 28 e 42 dias, peso corporal, massa magra, proteína, água corporal aos 42 dias de idade, peso ao abate, peso da carcaça quente, peso da carcaça fria, peso do peito, peso da coxa, peso da sobrecoxa, rendimento da coxa e rendimento da sobrecoxa, com machos apresentando respostas mais elevadas em comparação com fêmeas. Em relação à composição corporal aos 42 dias de idade, foram observadas quantidades maiores de massa magra, proteína e água em frangos de corte alimentados com os planos nutricionais TB 2024 e TB 2017. O menor peso corporal (P<0,05) foi determinado para o tratamento TB 1983, e uma quantidade menor de gordura (P<0,05) foi determinada para os planos nutricionais TB 2024 e COBB 2022 em comparação com TB 2017 e TB 1983. Para os rendimentos de carcaça e cortes, os programas nutricionais TB 2024 e TB 2017 promoveram peso maior de carcaça quente, peso de carcaça fria e peso de peito (P<0,05), enquanto o TB 2017 promoveu maior peso de coxa (P<0,05). Os resultados demonstraram que as atualizações dos planos nutricionais ao longo das últimas 4 décadas foram responsáveis por melhorias de 12% e 7,9% no GP para machos e fêmeas, respectivamente, e 26,1% e 26,7% na CA para machos e fêmeas, quando comparado ao plano nutricional referência em 1983, bem como promoveram otimiziação da composição corporal, do rendimento de carcaça dos frangos de corte e aumentaram o retorno econômico do investimento. Palavras-chave: composição corporal; desempenho; rendimento.Item Characterization of organic milk production systems in Brazil and the effect of a feed additive on intake, milk yield, and methane emission of holstein or holstein×gyr crossbred dairy cows(Universidade Federal de Viçosa, 2024-02-28) Sant'Ana, Amanda Barbosa; Silva, Alex Lopes da; http://lattes.cnpq.br/4876191792698599This dissertation was composed by two different studies, where the aim of the first study was to characterize organic milk production systems in Brazil and the aim of the second study was to evaluate the effect of a dietary supplement based on condensed tannins on the intake, milk yield, and methane (CH4) emission of Holstein or Holstein×Gyr crossbred lactating dairy cows. In the first study, a descriptive analysis was carried out in which the variables were geographical location, herd size, animal production, feed used, health and reproduction management, organic inputs used, feed production management, and transportation of products. The characteristics of the systems were evaluated according to the level of production, with farmers divided into 3 groups, with the upper extract comprising farms with an average production of over 16 L/cow per day (HIG), the medium extract with a production between 10.5 and 16 L/cow per day (MED) and the lower extract with an average production of less than 10.5 L/cow per day (LOW). The variables were subjected to binomial logistic regression and comparisons were made by odds ratio. The average area of the properties was 107 ha (minimum 3 ha and maximum 1,450 ha), the area for organic milk production was 44 ha (minimum 1 ha and maximum 550 ha). The average daily milk production was 645 L/day (minimum of 12 L/day and maximum of 5,000 L/day), with an average production of 13 L/cow per day (minimum of 4 L/cow per day and maximum of 25 L/cow per day). The herds have an average of 58 cows (minimum 2 cows and maximum 310 cows) and 40 lactating cows (minimum 2 and maximum 255 cows). The average annual production was 7,517 L/ha per year (minimum 21 L/ha per year and maximum 29,877 L/ha per year). The average number of family workers was 2 (minimum 2 and maximum 7), the average number of external workers was 3 (minimum 2 and maximum 16). The HIG and MED farms were found to be 90% less likely to produce cheese. In addition, HIG and MED farms were 10.7 and 6.6 times more likely to have Holstein×Jersey crosses in their herd, respectively. The MED farms were 80% less likely to have Urochloa spp pastures, while HIG farms were 93.2% less likely to have Urochloa spp pastures and 92% less likely to use chopped grass to supplement the herd. However, the odds of having Megathyrsus maximus pastures was 4.66 times greater for HIG. In addition, HIG farms were 4.5 times more likely to use any type of management software. The analysis of the distribution of certified organic dairy farms revealed a significant concentration in the Southeast region of Brazil. The distribution of certified organic dairy farms shows a concentration in the southeastern region of Brazil, where production is mainly focused on milk, while other regions have more diversified organic production. The HIG farms are more likely to use specialized cattle breeds, herd supplementation, pastures formed by higher-yielding forage species with greater nutritional value, and management software. These results emphasize the need for public policies that promote the adoption of technological and sustainable practices to increase the efficiency and productivity of the organic dairy sector. Concerning the second study, sixteen dairy cows (8 Holstein and 8 Holstein×Gyr) were allocated to two treatments: a control group (CON; no supplementation) and a supplemented group (SUP) that received 2.7 g/kg DM of the additive (Muucare Nature®). The trial lasted 84 days, including a 24-day adaptation period. The animals were housed in tie stalls and kept under identical conditions. Rumen fluid was collected via an esophagus on days 22 and 52, and the microbial composition was later analyzed by 16S rRNA sequencing. The VFA concentrations and rumen ammonia nitrogen were also quantified. Methane emission was measured using the sulfur hexafluoride tracer technique. The additive increased the apparent digestibility of DM and OM by about 6% without affecting feed intake or milk yield. Methane emission per ECM (g/kg) was reduced by almost 30%, and methane emission per milk yield (g/kg) showed a similar trend. The SUP cows showed higher propionate production and a lower acetate-to-propionate ratio, indicating a shift in fermentation. The microbial diversity in the rumen was altered, with a reduced alpha diversity and a different community composition, including an increased abundance of Prevotella ruminicola. The total amount of methanogens was unchanged, although one species, Methanobrevibacter smithii, tended to be less abundant. The additive reduced methane emission and improved nutrient digestibility, rumen fermentation, and nitrogen efficiency. These results indicate that the additive based on Acacia tannins and Saccharomyces cerevisiae yeast is a sustainable tool to reduce methane emissions in dairy production systems without compromising milk production. Keywords: bovines ; organic milk ; survey.Item Evaluation of genotype-environment interaction in poultry(Universidade Federal de Viçosa, 2025-07-28) Reis, Arícia Chaves Zanetti; Veroneze, Renata; http://lattes.cnpq.br/4083615365354531This thesis investigates genotype-by-environment interaction (GEI) in poultry, aiming to understand how different genotypes change across to environmental variation. GEI occurs when the performance of animals changes depending on the environment, which may lead to reranking of selection candidates. Although GEI has already been studied in commercial chickens, species such as quails and turkeys remain underexplored. This research aims to fill this gap by analyzing two important traits: body weight in meat quails and walking ability in turkeys, both influenced by environment and related to animal performance and welfare. The first study evaluated body weight from 7 to 42 days of age in meat quails raised under two classes of temperature-humidity index (THI). Genetic correlations between THI classes were low to moderate at early ages, indicating the presence of GEI and reranking of individuals. From 28 days, high genetic correlations were observed, suggesting more stable genetic expression under thermal stress. The second study assessed GEI for walking ability in turkeys using data from over 190,000 birds. Environmental gradients were defined based on contemporary group effects for body weight. Reaction norm models with different residual variances were compared. The best-fitting model indicated genetic variation in walking ability across environments and reranking of individuals across the environmental gradient. An inverse relationship between body weight and walking ability was also observed, reinforcing the importance of considering GEI in selection strategies. The results highlight the relevance of including GEI in genetic evaluations. This thesis contributes to expanding knowledge on GEI in poultry and supports the development of breeding programs focused on both productivity and animal welfare. Keywords: genotype-by-environment interaction; poultry; quails; turkeysItem Silagens de dietas totais contendo sorgo exclusivo ou associado com amendoim forrageiro tratadas com inoculantes bacterianos(Universidade Federal de Viçosa, 2025-02-12) Fernandes, Thiago da Silva; Pereira, Odilon Gomes; http://lattes.cnpq.br/7044093501144574Avaliou-se o perfil fermentativo e a estabilidade aeróbia de silagens de dieta total (TMR) contendo sorgo como único volumoso (TMR1) ou sorgo associado ao amendoim forrageiro (TMR2), na relação volumoso:concentrado de 50:50, com ou sem inoculante microbiano, em esquema fatorial 2 × 2 com cinco repetições, em delineamento inteiramente casualizado. A inclusão de amendoim forrageiro representou 25% da matéria seca do volumoso na TMR2. O inoculante utilizado foi o MAGNIVA PLATINUM 1®, contendo as cepas L. hilgardii CNCM I-4785 e L. buchneri NCIMB 40788. Observou-se efeito significativo (P < 0,05) da interação silagem × inoculante sobre os teores de amido, FDNcp e CHOS, e efeito da silagem sobre MS, PB, EE, FDA, pH, N-NH3, ácido acético, ácido propiônico e leveduras. Verificou-se também efeito do inoculante sobre FDA, bactérias ácido-láticas (BAL), ácido acético, ácido propiônico e leveduras. Registrou-se maior teor de MS (418,64 g/kg) nas silagens inoculadas, enquanto a TMR1 apresentou maior teor de MS (424,08 g/kg) em comparação à TMR2. O maior conteúdo de amido (383,23 g/kg) foi observado na silagem TMR1 não inoculada. A concentração de carboidratos solúveis residuais (23,72 g/kg) foi superior na TMR1 em relação à TMR2. Foram registradas maiores populações de BAL (6,67 vs. 5,76 log10 UFC/g) e menores de leveduras (2,74 vs. 3,68 log10 UFC/g) nas silagens inoculadas. Após a abertura dos silos, não foram detectados fungos filamentosos em nenhuma das silagens avaliadas, incluindo as silagens inoculadas após exposição aeróbia. Em ambas as TMRs, observou-se maior estabilidade aeróbia (P < 0,05) nas silagens inoculadas em comparação às não inoculadas. Conclui-se que o uso do inoculante microbiano proporcionou melhor estabilidade aeróbia e menor população de leveduras nas silagens TMR1 e TMR2. Palavras-chave: silagem; fermentação; estabilidade aeróbiaItem Metabolizable and net energy requirements for entire and immunocastrated male pigs and digestible lysine for immunocastrated males(Universidade Federal de Viçosa, 2025-07-15) Barcellos, Joyce; Hannas, Melissa Izabel; http://lattes.cnpq.br/9743311986235203In the first chapter, the objective was to determine the metabolizable and net energy requirements for maintenance and production of entire males and immunocastrated males from 70 to 130 kg of body weight, using the factorial method. Sixty entire male pigs were randomly assigned to a performance trial with four treatments (ad libitum, 75%, 50%, and 25% of the ad libitum feed), with 12 replicates and one pig per pen. The parameters of the energy model were established using the comparative method for protein and fat deposition through the Dual-Energy X-ray Absorptiometry (DEXA) approach. Energy requirements for weight gain were determined based on body energy content and the efficiency of energy utilization for weight gain. Metabolizable energy (ME) and net energy (NE) requirements for maintenance (MEm and NEm) were 160.33 and 134.52 kcal/kg BW0.75 per day, respectively, for entire males. The efficiency of utilization of ME for NE was 0.84, estimated from the slope of the linear regression equation of retained energy as a function of metabolizable energy (ME) intake. The ratio of lean to fat mass decreased during the growth period and was more pronounced in immunocastrated males, indicating that fat retention becomes more energy-efficient as body weight increases. Entire male pigs are less demanding in net energy for gain (NEg) than immunocastrated males. The ME and NE requirements for production (MEp and NEp) were 4.498 and 3.779 kcal per kilogram of body weight for entire males, and 5.298 and 4.451 kcal for immunocastrated males, respectively. The second chapter evaluated digestible lysine (DLys) levels in the diet of immunocastrated male pigs during the finishing phase regarding performance, in vivo body composition, carcass traits, and meat quality, as well as to determine DLys requirements. Sixty immunocastrated male pigs were randomly allotted to five treatments with DLys levels of 0.55, 0.61, 0.68, 0.75, and 0.82%, respectively, in 12 replicates. Overall, performance improved in response to increasing DLys levels. Carcass yield and loin weight increased linearly (P < 0.05) with increasing DLys levels, whereas loin area (LA) showed a quadratic increase (P < 0.05). Meat quality was affected, showing a linear increase in sarcomere length, drip loss (P < 0.10), and color values a* and b* (P < 0.05), as well as changes in the chemical composition of loin chops, with a quadratic decrease for intramuscular fat and crude protein in dry matter (P< 0.05). Body composition was affected, with a linear increase in fat mass gain and a quadratic increase in bone mineral content (BMC) gain (P < 0.05); however, only total body fat gain increased significantly. The DLys requirement was estimated at 0.74% for carcass parameters (carcass yield and loin weight) using the quadratic model, and for ADG using the linear-plateau model. A daily intake of 33 g DLys/day for 1.79 kg/day of ADG, or 17.90 g DLys per kg of body weight gain, is recommended for immunocastrated male pigs housed individually during the finishing phase. Keywords: nutritional requirements; body composition; DEXA; factorial method.Item Evaluation of different minerals as mixing efficiency marker in commercial mixers(Universidade Federal de Viçosa, 2025-07-11) Vidal, Raphaela Cenci; Rotta, Polyana Pizzi; http://lattes.cnpq.br/7867647834586230This thesis was divided into two products. Product 1 (Scientific article) - Performing a homogeneity test of the feed mixture is essential for quality assurance in feed mills. The aim of this study was to evaluate different minerals as test markers for the quality of feed mixtures in commercial mixers and to evaluate the sampling procedures for the standardization of homogeneity testing of mixtures in animal feed. Four horizontal, spiral-shaped, commercially available mixers were used for the test. Feed samples were taken from four different commercial mixers on five consecutive days to evaluate the quality of the mix. A total of 200 samples were taken during the entire test period (4 mixers × 5 days × 1 batch per day and mixer × 10 samples). Samples were taken sequentially during the mixer discharge time, with the total discharge time (4 minutes) divided into 10 equal 24-second intervals. All test portions were analyzed to determine the content of calcium (Ca), phosphorus (P), potassium (K), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn). All statistical analyzes were performed using the GLIMMIX procedure of SAS 9.4 (a = 0.05) to check the variability of mineral markers for mixers, among batches and increments. Minerals K and Mg showed the lowest standardized total amplitudes and variation indices, which tended to zero, and are considered reliable for evaluating mix quality. In addition, a two-point sampling strategy was defined and proposed for animal feed. Product 2 (Book) – The aim of this literary work was to compile relevant data and make it available in the form of a book that will be published by Editora UFV under the title “The Fantastic World of Feed Mills”. The aim was to inform professionals involved in the operation of feed mills about the importance of feed quality and food safety. In addition, the book informs the reader about the importance of implementing Good Manufacturing Practices and other quality management tools, such as quality control of manufactured products, as well as the regulatory authorities and current legislation in Brazil. Keywords: Feed mills; Food safety; Homogeneity; Legislation; Mineral markersItem Associative effects of nutrition and production in grazing beef cows and calves(Universidade Federal de Viçosa, 2025-07-18) Pereira, Pedro Henrique Borba; Sampaio, Claudia Batista; http://lattes.cnpq.br/7550463374087975For this thesis, three (03) chapters were developed, integrating studies with beef cows and calves raised under grazing systems. The first study was conducted under grazing conditions, evaluating the effect of calf sex and creep-feeding supplementation on the productive performance and blood metabolism of Nellore cows. The second study applied a meta-analysis approach to assess protein supplementation of grazing Nellore cows during the peripartum period and its effects on energy metabolism. The third chapter was a literature review addressing the effects of vitamin A supplementation on maternal performance and the nutri- epigenetic effects on calves. In the first chapter, the objective was to evaluate the interaction between calf sex and creep-feeding supplementation on body weight (BW), body condition score (BCS), milk yield, and blood metabolic profile of grazing Nellore cows. A total of 55 multiparous Nellore cows were used, with an average BW of 520 ± 59.2 kg, average BCS of 4.5 ± 0.46, and approximately 230 ± 6 days of gestation. Fetal sex was determined, resulting in 29 males and 28 females. Cow-calf pairs (considering fetal sex) were randomly assigned to eight paddocks in a completely randomized design with a double-error structure, with both male and female calves coexisting within each paddock. Four paddocks were allocated to the Control calves’ group (CON; mineral mix ad libitum), and four paddocks to the Supplemented calves’ group (SUP; protein-energy supplementation containing 260 g/kg crude protein on a dry matter basis, offered at 6 g/kg BW per animal). Cows received a protein-energy supplement containing 350 g/kg crude protein (CP) on a dry matter (DM) basis infrequently during the last 30 days of gestation, and after calving, they received only a mineral mix ad libitum until weaning. Maternal BW and BCS were recorded at -30, 1, 30, 100, and 240 days relative to calving (day 0). Milk yield (MY) was estimated by double milking at approximately 45 and 240 days relative to calving, with adjustment to daily yield. Calf BW was measured approximately 12 h after birth and at 30, 100, and 240 days of age. Blood samples from cows were collected at -30, 1, 30, 100, and 240 days relative to calving to determine plasma concentrations of glucose, ß-hydroxybutyrate (ß-OHB), non- esterified fatty acids (NEFA), total protein, albumin, blood urea nitrogen, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma- glutamyltransferase (GGT). No interaction (P > 0.05) was detected between calf sex and creep-feeding supplementation for BW, BCS, MY, or blood metabolites of cows. However, supplementation interacted with calf BW (P < 0.001), and calf sex interacted with calf BW (P < 0.001). Only the effect of time influenced cow performance and blood metabolites (P < 0.05). Thus, calf sex and creep-feeding supplementation did not impair productive performance or metabolic profile of grazing Nellore cows. In the second chapter, the objective was to evaluate the effects of maternal supplementation during pre- and/or postpartum on performance and blood concentrations of glucose, NEFA, and ß-OHB in Nellore cows grazing tropical pastures, using a meta-analytical approach. The database was compiled from 17 experiments conducted in Brazil between 2016 and 2025, with 654 observations, totaling 80 treatments across 150 experimental units. All studies adopted maternal supplementation in pre- and postpartum as the fixed-effect model (control: mineral mix ad libitum; supplemented: average of 309 g/kg CP in DM during prepartum and average of 319 g/kg CP in DM during postpartum), adjusted for animal category (multiparous cows and primiparous heifers). Prepartum supplementation increased BW at calving (P < 0.001), improved average daily gain (P = 0.01), and reduced plasma NEFA concentrations (P < 0.001), compared with non-supplemented cows. Based on the results, the estimated composition for prepartum supplementation is 309 g/kg CP in DM, with an allowance of 3.00 g/kg BW per day, to ensure positive performance responses in Nellore cows. No interaction was detected between prepartum and postpartum supplementation (P > 0.05). Postpartum supplementation had no significant effect on BW or blood concentrations of glucose, NEFA, and ß- OHB (P > 0.05). Therefore, prepartum protein supplementation of Nellore cows grazing tropical pastures modulates circulating NEFA concentrations and improves maternal performance, without affecting energy metabolism or postpartum performance. In the third chapter, the objective was to discuss the dynamics of vitamin A supplementation and its effects on gestational/maternal and neonatal metabolism in beef cattle, through a literature review. Vitamin A, a fat-soluble vitamin, regulates reproductive functions, growth, and tissue maintenance through gene expression. In ruminants, this micronutrient may be supplemented orally as ß- carotenoids or intramuscularly as exogenous retinol. In pregnant beef cows, oral supplementation during mid- or late-gestation increases plasma retinol concentrations, enhancing fetal development, colostrum production, and postpartum fertility. In newborn beef calves, intramuscular administration of vitamin A stimulates lipogenesis, muscle growth, and meat quality. Given the increasing evidence of the importance of vitamin A for maternal and neonatal health, there is strong potential to optimize supplementation strategies. Future studies should investigate the long-term effects of different vitamin A supplementation protocols on hepatic retinol retention in dams and their impacts on progeny, particularly regarding fetal development and postnatal growth under grazing conditions. The improvement of such nutritional interventions contributes to more efficient and sustainable beef production systems, with greater economic benefits for producers. Keywords: creep-feeding; metabolism; Nellore; supplementation; vitamin A