Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 541958
Title Nitrate improves ammonia incorporation into rumen microbial protein in lactating dairy cows fed a low-protein diet
Author(s) Wang, Rong; Wang, Min; Ungerfeld, Emilio M.; Zhang, Xiu Min; Long, Dong Lei; Mao, Hong Xiang; Deng, Jin Ping; Bannink, André; Tan, Zhi Liang
Source Journal of Dairy Science 101 (2018)11. - ISSN 0022-0302 - p. 9789 - 9799.
DOI https://doi.org/10.3168/jds.2018-14904
Department(s) WIAS
LR - Animal Nutrition
Publication type Refereed Article in a scientific journal
Publication year 2018
Keyword(s) dissolved hydrogen - microbial protein - nitrate - rumen fermentation
Abstract

Generation of ammonia from nitrate reduction is slower compared with urea hydrolysis and may be more efficiently incorporated into ruminal microbial protein. We hypothesized that nitrate supplementation could increase ammonia incorporation into microbial protein in the rumen compared with urea supplementation of a low-protein diet fed to lactating dairy cows. Eight multiparous Chinese Holstein dairy cows were used in a crossover design to investigate the effect of nitrate or an isonitrogenous urea inclusion in the basal low-protein diet on rumen fermentation, milk yield, and ruminal microbial community in dairy cows fed a low-protein diet in comparison with an isonitrogenous urea control. Eight lactating cows were blocked in 4 pairs according to days in milk, parity, and milk yield and allocated to urea (7.0 g urea/kg of dry matter of basal diet) or nitrate (14.6 g of NO3 /kg of dry matter of basal diet, supplemented as sodium nitrate) treatments, which were formulated on 75% of metabolizable protein requirements. Nitrate supplementation decreased ammonia concentration in the rumen liquids (−33.1%) and plasma (−30.6%) as well as methane emissions (−15.0%) and increased dissolved hydrogen concentration (102%), microbial N (22.8%), propionate molar percentage, milk yield, and 16S rRNA gene copies of Selenomonas ruminantium. Ruminal dissolved hydrogen was positively correlated with the molar proportion of propionate (r = 0.57), and negatively correlated with acetate-to-propionate ratio (r = −0.57) and estimated net metabolic hydrogen production relative to total VFA produced (r = −0.58). Nitrate reduction to ammonia redirected metabolic hydrogen away from methanogenesis, enhanced ammonia incorporation into rumen microbial protein, and shifted fermentation from acetate to propionate, along with increasing S. ruminantium 16S rRNA gene copies, likely leading to the increased milk yield.

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