Strategic grazing management decreases nitrogen excretion intensity of dairy cows

Autor(es)

Araujo Batalha, Camila Delveaux ^[1] ; Souza Congio, Guilhermo Francklin de ^[1] ; Portela Santos, Flavio Augusto ^[1] ; da Silva, Sila Carneiro ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, ESALQ, Dept Zootecnia, CP 09, BR-13418900 Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Scientia Agricola; v. 79, n. 2 2022.
• Citações Web of Science: 0

Resumo

ABSTRACT: There is limited information regarding both nitrogen (N) and energy partitioning of dairy cows grazing well–managed tropical pastures. The objective of this study was to investigate the N and energy partitioning of mid–lactation dairy cows on rotationally grazed elephant grass using two pre–grazing targets: 95 % or maximum canopy light interception (LI95% or LIMax) during regrowth. The study used 26 Holstein × Jersey dairy cows arranged in a randomized complete block design with three 40–day periods of sampling. Grazing at LI95% increased organic matter and crude protein intake by 20 % (p ≤ 0.05) which resulted in a 9 % increase in fat corrected milk yield (p ≤ 0.05) relative to LIMax. Cows grazing at LI95% had greater concentration of total volatile fatty acids, butyrate and valerate (p ≤ 0.05), and smaller acetate (p ≤ 0.05) than those grazing at LIMax. Intake of net energy for lactation (NEL) and NEL secreted in milk were greater (p ≤ 0.05), while partitioning of NEL towards maintenance tended to be greater (p = 0.07) for cows grazing at LI95% than those grazing at LIMax. Milk urea nitrogen and both urine and fecal N excretion were greater for cows grazing at LI95% (p ≤ 0.05), but N excretion intensity was lower than in cows grazing at LIMax (p ≤ 0.05). Strategic grazing management using the LI95% pre–grazing target increases N losses through both urine and feces; however, it reduces N excretion intensity of dairy cows by 9 %. (AU)

• Processo FAPESP: 16/22040-2 - Valor nutritivo, produção de leite e emissões de gases de efeito estufa em capim-elefante cv. cameroon submetido a estratégias de pastejo rotativo por vacas leiteiras
• Beneficiário: Sila Carneiro da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Regular