Technological advances in milk production systems are related to genetic improvement and nutritional management. Genetic improvement has made it possible to obtain animals increasingly more productive, which implies a greater demand for nutrients and, consequently, a finer adjustment of diets, in order to meet the nutritional requirements of the animals and reduce the incidence of metabolic disorders (acidosis, laminitis, hypocalcemia, etc.). Another important factor to be evaluated is the use of essential oils (EOs) as substitutes for antibiotics (ionophores), associated or not with exogenous enzymes (amylase). EOs have shown the potential to act as substitutes for antibiotics, given the possibility of their use as an antimicrobial agent, and can act as a modulator of ruminal fermentation through their non-specific antimicrobial action, altering the metabolism of the ruminal microbiota. The use of exogenous amylolytic enzymes aims to increase the efficiency of use of dietary starch, reducing energy and nitrogen losses in digestion processes, with an expected positive impact on animal performance. In this project, nutritional management strategies for the transition and lactation periods were studied, with a view to improving the economic and productive efficiencies of the production system. Therefore, one of the objectives of this project was to evaluate the effects of calcidiol (25-hydroxyvitamin D3; 25 (OH) D3) and vitamin D3 (cholecalciferol) on plasma concentrations of minerals and metabolites, mineral balance, mineral excretion, energy balance and milk production from dairy cows in the transition period. The hypothesis was that supplementation with 3.0 mg/day of 25(OH)D3 during the pre-partum period would be more effective than supplementation with cholecalciferol, aiming to minimize calcium imbalance during the transition period and increase milk production. There was a tendency for an increase in plasma ionized Ca levels in cows fed 25(OH)D3 compared to those treated with cholecalciferol; however, no effect was detected for total Ca and total P concentrations. Supplementation with 25(OH)D3 increased colostrum production, plasma 25-hydroxyvitamin D3 concentration and plasma glucose concentration at calving. Postpartum dry matter intake was not influenced by the source of vitamin D3. There was also an increase in milk production and milk production corrected for fat and energy, as well as an improvement in the composition of milk at the beginning of lactation. The results suggest that supplementation with 25(OH)D3 can improve mechanisms of Ca homeostasis and performance of lactation compared to conventional feeding practices that use cholecalciferol as a source of vitamin D3. The other objective of the project was to evaluate the effects of supplementation with EOs associated or not with amylase on the productive performance of lactating Holstein cows. The following treatments were evaluated: a) control, without additives; b) essential oils (EOs), addition of essential oil blends; and c) amylase + essential oils (Am+OEs), a combination of essential oils and α-amylase. Supplementation with additives did not influence dry matter intake (23.9 kg/day). However, the use of Am+OEs increased feed efficiency (1.40) compared to control and supplementation with EO alone (1.27 and 1.21, respectively). There was an increase in milk production for cows supplemented with Am+OEs, compared to the non-supplemented group (32.2 vs. 28.7 kg/day, respectively). There were no differences for fat (37.4 g/kg), lactose (45.6 g/kg) and milk urea nitrogen (17.3 mg/dL) content. The use of essential oils associated with amylase increases milk production and improves feed efficiency in cows in the middle third of lactation. The information presented in this document contributes to achieving the Sustainable Development Goals (SDGs) number 1 - Eradication of poverty: End poverty in all its forms, everywhere; 2 - Eradication of hunger: End hunger, achieve food security and improved nutrition and promote sustainable agriculture; 8 - Dignified employment and economic growth: Promoting growth sustained, inclusive and sustainable economic development, full and productive employment, and decent work for all).