Long-Term encapsulated nitrate supplementation modulates rumen microbial diversity and rumen fermentation to reduce methane emission in grazing steers.

This study investigated the long-term effects (13 months) of encapsulated nitrate supplementation (ENS) on enteric methane emissions, rumen fermentation parameters, ruminal bacteria, and diversity of archaea in grazing beef cattle. We used a total of thirty-two Nellore steers (initial BW of 197 15.3 kg), 12 of which were fitted with rumen cannulas. For 13 months, the animals were maintained in 12 paddocks and fed a concentrate of ground corn, soybean meals, mineral supplements, and urea (URS) or encapsulated nitrate (EN) containing 70 g of EN/100 kg of BW (corresponding to 47 g NO3/100 kg BW). Encapsulated nitrate supplementation resulted in similar forage, supplement and total DMI values as URS (P > 0.05), but ENS tended to increase (C48 g/d; P = 0.055) average daily weight gain. Daily reductions in methane emissions (- 9.54 g or 18.5%) were observed with ENS when expressed as g of CH4/kg of forage dry matter intake (fDMI) (P = 0.037). Lower concentrations of NH3-N and a higher ruminal pH were observed in ENS groups 6 h after supplementation (P < 0.05). Total VFA rumen concentration 6 h (P = 0.009) and 12 h after supplementation with EN resulted in lower acetate concentrations in the rumen (P = 0.041). Steers supplemented with EN had a greater ruminal abundance of Bacteroides, Barnesiella, Lactobacillus, Selenomonas, Veillonella, Succinimonas, Succinivibrio, and Duganella sp. (P < 0.05), but a lower abundance of Methanobrevibacter sp. (P = 0.007). Strong negative correlations were found between daily methane emissions and Proteobacteria, Erysipelotrichaceae, Prevotellaceae, and Roseburia, Kandleria, Selenomonas, Veillonella, and Succinivibrio sp. (P < 0.05) in the rumen of ENS steers. Encapsulated nitrate is a feed additive that persistently affects enteric methane emission in grazing steers, thereby decreasing Methanobrevibacter abundance in the rumen. In addition, ENS can promote fumarate-reducer and lactateproducer bacteria, thereby reducing acetate production during rumen fermentation.

Bibliographic Details

Main Authors:	GRANJA-SALCEDO, Y. T., FERNANDES, R. M., ARAUJO, R. C. de, KISHI, L. T., BERCHIELLI, T. T., RESENDE, F. D. de, BERNDT, A., SIQUEIRA, G. R.
Other Authors:	Yury Tatiana Granja-Salcedo, UNESP; Rodolfo Maciel Fernandes, UNESP/Agência Paulista de Tecnologia dos Agronegócios; Rafael Canonenco de Araujo, GRASP; Luciano Takeshi Kishi, UNESP; Telma Teresinha Berchielli, UNESP; Flávio Dutra de Resende, UNESP; ALEXANDRE BERNDT, CPPSE; Gustavo Rezende Siqueira, UNESP/Agência Paulista de Tecnologia dos Agronegócios.
Format:	Artigo de periódico biblioteca
Language:	English eng
Published:	2019-04-03
Subjects:	Archaea diversity, Enteric methane emission, Gado de Corte, Nitrato, Beef cattle, Rumen bacteria, Fatty acids,
Online Access:	http://www.alice.cnptia.embrapa.br/alice/handle/doc/1107883
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