Efeito de diferentes suplementos na dieta de vacas leiteiras em pastagem temperada

• Ano de defesa: 2024
• Autor(a) principal: Dalgallo, Daniel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Tecnológica Federal do Paraná; Dois Vizinhos; Brasil; Programa de Pós-Graduação em Zootecnia; UTFPR
• Palavras-chave em Português: Bovinos de leite; Proteínas na nutrição animal; Leite - Qualidade; Dairy cattle; Proteins in animal nutrition; Milk - Quality; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA; ZOOTECNIA
• Link de acesso: http://repositorio.utfpr.edu.br/jspui/handle/1/37130

Concentrated supplementation, when used rationally, allows maximizing the productive potential of lactating cows under grazing conditions. In this sense, the objective of this work was to evaluate three supplementation strategies on productive parameters of dairy cows grazing ryegrass. Our hypothesis is that under conditions of non-limiting forage supply and high protein value, dairy cows tend not to respond to energy-protein supplementation. The experiment was conducted on a rural property in the municipality of Porto União, SC, from July to September 2023, in winter pasture areas, with annual ryegrass – cultivar KLM 138. A completely randomized design was used, with four replications (cows) and three treatments: CORN – energy supplement with ground corn; CONC18 – supplementation with commercial concentrate containing 18% crude protein; FORMUL – concentrated supplementation formulated with corn and soybean hulls, based on the bromatological composition of the pasture. Three evaluation periods were carried out (July, August and September), each lasting twenty days, with 17 days for adaptation and 3 days for collecting samples from the animals. The variables evaluated in the cows were: milk production, fat content, protein, lactose, total solids and urea nitrogen in milk (NUL); dry matter consumption (chromium oxide method) and nitrogen excretion in feces and urine. In the pasture, dry mass production and chemical composition were evaluated in each period. The data were subjected to analysis of variance and the means compared using the T test at a 5% significance level. No effects of treatments were observed on milk production, which was on average 23, 23 and 20 kg of milk/cow/day, respectively for periods 1, 2 and 3 of evaluation. The type of supplementation influenced the composition of the milk, with a higher crude protein content and a lower NULL content (10mm.l-1 ) in the treatment with only corn. The provision of protein supplements in both CONC18 and FORM promoted an increase in NUL levels (17mm.l-1 ) and a reduction in milk protein concentration. On effects of the diets on the fat content of milk were observed in any period, which averaged 4.02%. The ryegrass pasture was maintained with an average supply of 1000kgDM.ha-1, with a grazing height of 7cm above the ground and with crude protein levels above 30% in the first period and DIVMO above 72% in all periods.