Recria de tourinhos nelore em pastos de capim marandu sob adubação nitrogenada
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Data
2021-11-05
Autores
Leite, Rhaony Gonçalves [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
No presente trabalho foi avaliado os efeitos de diferentes doses de adubo nitrogenado aplicadas as pastagens de Urochloa brizantha cv. Marandu durante a estação chuvosa sobre a massa de forragem (MF), os componentes estruturais das plantas forrageiras, taxa de acúmulo, o índice nutricional de nitrogênio - INN, a eficiência de uso do nitrogênio, a qualidade da forragem, o desempenho animal e o fracionamento de carboidratos e proteína. O delineamento experimental foi inteiramente casualizado com quatro tratamentos (controle sem aplicação de N, e 90, 180 e 270 kg de N ha-1 ano-1 ) e três repetições (piquetes por tratamento). O nitrogênio foi aplicado na forma de ureia divida em 3 aplicações. O experimento foi repetido por dois anos consecutivos (2017-2018 e 2018-2019). Massa de forragem, taxa de acúmulo de forragem, taxa de lotação e ganho por área aumentaram com o aumento das doses de nitrogênio (P < 0,05), enquanto carboidratos totais (CT), fibra em detergente neutro (FDNcp), fibra em detergente neutro indigestível (FDNi), a oferta de forragem e eficiência do uso nitrogênio diminuiu com o aumento da dose de nitrogênio (P<0,05). A proteína bruta (PB), fração A+B1, fração C e consumo de PB por kg de matéria orgânica digestível (MOD) aumentaram, e a fração C diminuiu linearmente com as doses de nitrogênio (P <0,05). O aumento nas doses de N reduziu os teores de FDNcp de 612 para 550 g kg-1 MS, de fração C da proteína de 125 para 98 g kg-1 PB e de EUN de 97 para 41 kg MS kg-1 N aplicado e aumentou os teores de proteína solúvel de 363 para 433 g kg-1 PB e a PB de 115 para 193 g kg-1 MS. Portanto, o aumento das doses de adubo nitrogenado é uma alternativa viável para aumentar a produção de capim Marandu, o valor nutritivo e a produção animal, além de aumentar as frações mais solúveis de carboidratos e proteína.
In the present study, the effects of different doses of nitrogen fertilization applied to pastures of Urochloa brizantha cv. Marandu during the rainy season on forage mass (FM), structural components of forage plants, accumulation rate, nitrogen nutritional index - INN, nitrogen use efficiency, forage quality, animal performance and fractionation of carbohydrates and protein. The experimental design was completely randomized with four treatments (control without N application, and 90, 180 and 270 kg of N ha-1 yr-1) and three replications (paddocks per treatment), nitrogen was applied in the form of urea divide in 3 applications. The experiment was repeated for two consecutive years (2017- 2018 and 2018-2019). Forage mass, forage accumulation rate, stocking rate and area gain increased with increasing nitrogen doses (P < 0.05), while total carbohydrates (TC), neutral detergent fiber (NDFap), fiber in indigestible neutral detergent (NDFi), forage supply and nitrogen use efficiency decreased with increasing nitrogen dose (P<0.05). Crude protein (CP), fraction A+B1, fraction C and CP intake per kg of digestible organic matter (MOD) increased, and fraction C linearly decreased with nitrogen doses (P < 0.05). The increase in N doses reduced the levels of NDFcp from 612 to 550 g kg-1 DM, of protein C fraction from 125 to 98 g kg-1 CP and of EUN from 97 to 41 kg DM kg-1 N applied and increased soluble protein contents from 363 to 433 g kg-1 CP and CP from 115 to 193 g kg-1 DM. Therefore, increasing nitrogen fertilizer doses is a viable alternative to increase Marandu grass production, nutritional value and animal production, in addition to increasing the more soluble carbohydrate and protein fractions.
In the present study, the effects of different doses of nitrogen fertilization applied to pastures of Urochloa brizantha cv. Marandu during the rainy season on forage mass (FM), structural components of forage plants, accumulation rate, nitrogen nutritional index - INN, nitrogen use efficiency, forage quality, animal performance and fractionation of carbohydrates and protein. The experimental design was completely randomized with four treatments (control without N application, and 90, 180 and 270 kg of N ha-1 yr-1) and three replications (paddocks per treatment), nitrogen was applied in the form of urea divide in 3 applications. The experiment was repeated for two consecutive years (2017- 2018 and 2018-2019). Forage mass, forage accumulation rate, stocking rate and area gain increased with increasing nitrogen doses (P < 0.05), while total carbohydrates (TC), neutral detergent fiber (NDFap), fiber in indigestible neutral detergent (NDFi), forage supply and nitrogen use efficiency decreased with increasing nitrogen dose (P<0.05). Crude protein (CP), fraction A+B1, fraction C and CP intake per kg of digestible organic matter (MOD) increased, and fraction C linearly decreased with nitrogen doses (P < 0.05). The increase in N doses reduced the levels of NDFcp from 612 to 550 g kg-1 DM, of protein C fraction from 125 to 98 g kg-1 CP and of EUN from 97 to 41 kg DM kg-1 N applied and increased soluble protein contents from 363 to 433 g kg-1 CP and CP from 115 to 193 g kg-1 DM. Therefore, increasing nitrogen fertilizer doses is a viable alternative to increase Marandu grass production, nutritional value and animal production, in addition to increasing the more soluble carbohydrate and protein fractions.
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Palavras-chave
Pastagens, Adubação, Gado, Capim