O presente trabalho teve como objetivo comparar a inclusão de quatro níveis de casca de soja como componente de rações concentradas para desaleitamento precoce de bezerros. Foram utilizados 36 bezerros, sendo 24 da raça Holandesa e 12 da raça Jersey, submetidos a quatro níveis de casca de soja (0, 15, 30 e 45%) adicionados em rações concentradas à base de milho, farelo de soja, palatabilizante e núcleo mineral, com 20% de proteína bruta. A duração do experimento foi de 16 semanas, considerando-se as fases de aleitamento (1-8 semanas) e pós-aleitamento (9-16 semanas). Na fase de aleitamento os animais receberam 4,0 kg de leite/dia, distribuídos em duas vezes, concentrado e água fornecidos à vontade. Após o desaleitamento os animais foram alimentados com concentrado e água à vontade e feno de alfafa na proporção de 20% do concentrado. Avaliou-se peso vivo, ganho de peso, altura à cernelha e ganho em altura, consumo de concentrado e volumoso e conversão alimentar (kg de MS ingerida / kg de ganho de peso). Os tratamentos não afetaram nenhuma das variáveis analisadas (P>0,05). Conclui-se que a casca de soja pode ser incluída em até 45% das rações concentradas para bezerros desaleitados com oito semanas de idade.

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The indiscriminate use without criteria of nitrogen fertilization can lead to an accumulation of nitrate in pastures, animal poisoning and potential increase in residual content of this compound in milk. The objective of this study was to determine the residual levels of nitrate throughout the year in pastures and milk from small farms in western Santa Catarina (SC) that use high levels of nitrogen fertilization. The experiment was carried out from April/2018 to March/2019 on 10 dairy farms in the municipality of Riqueza (SC). Two annual collections of water samples and monthly collections of pastures and milk were carried out, in addition to obtaining information on the property and management of pasture fertilization through a structured questionnaire. Nitrate was also evaluated in pastures using the diphenylamine test. Temperature and rainfall data were obtained daily by a weather station. The average amount of nitrogen fertilizer used in the properties was 654 ± 176 kg/ha/year. The average nitrate content in the drinking water of the animals was 1.5 ± 1.4 mg/L, in the pasture it was 270 ± 76 mg/kg DM, while in milk it was 2.0 ± 0.3 mg/L. There was seasonal variation with an increase in nitrate content in pastures and milk in autumn, a period of the experiment in which low rainfall was observed. It was concluded that despite being dairy properties with high use of nitrogen fertilization, safe milk is produced in terms of nitrate levels, even in times of the year with adverse climatic conditions. The diphenylamine test has a good ability to discriminate the nitrate content in pastures and can be indicated as a quick test to verify the presence of high levels of nitrate in the pasture.