Strategic grazing management decreases nitrogen excretion intensity of dairy cows
Batalha, Camila Delveaux Araujo; Congio, Guilhermo Francklin de Souza; Santos, Flávio Augusto Portela; Silva, Sila Carneiro da.
Sci. agric;
79(02): 1-7, 2022. tab
Artigo
em Inglês
| VETINDEX
| ID: biblio-1498035
Resumo
There is limited information regarding both nitrogen (N) and energy partitioning of dairy cows grazing wellmanaged tropical pastures. The objective of this study was to investigate the N and energy partitioning of midlactation dairy cows on rotationally grazed elephant grass using two pregrazing 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 40day 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% pregrazing target increases N losses through both urine and feces; however, it reduces N excretion intensity of dairy cows by 9 %.
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BR68.1
Localização: BR68.1
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