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Effect of NPN Source, Dietary Protein Level, and Production Level on Methane Emission in Dairy Cows

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Nitrate is a hydrogen sink and is expected to reduce methane. The aim of this study was to investigate the interaction between NPN source, dietary protein level, and production level (genetic yield index) on methane emission in dairy cows. Forty-eight Danish Holstein dairy cows (24 primiparous; 24 multiparous) were used in a 6 × 4 incomplete Latin square design. Cows were blocked in 8 groups based on parity and DIM. Six experimental diets were formulated and included 2 NPN-sources (nitrate or urea) × 3 crude protein (CP) levels (low, medium, and high; 144, 154, 163 g CP/kg DM) in a factorial arrangement. Gas emission was measured by 4 GreenFeed units. Data were analyzed in R studio (version 3.6.3) using the Linear Mixed-Effects Models procedure. Milk yield and energy-corrected milk yield (ECM) decreased as the CP level increased, while milk fat and urea concentration increased. The addition of nitrate significantly reduced DMI, ECM, CH4 production, CH4/DMI, CH4/ECM, and milk protein and lactose concentrations, whereas H2 production and milk urea concentration were increased. As production level of cows increased, DMI, ECM, and daily milk fat and protein yield increased. Reduction effect of NPN addition on DMI, ECM, and daily CH4 and CO2 production was greater on multiparous cows than primiparous cows. No interactions were observed between production level and NPN source and between CP level and NPN source on methane emission. In conclusion, dietary CP level had no effect on methane emission in dairy cows, nitrate addition reduced DMI, ECM, and CH4 and CO2 production and increased H2 production. However, there was no interaction between NPN source, dietary protein level, and production level on methane emission.
Original languageEnglish
Title of host publicationProceedings of the 8th International Greenhouse Gas & Animal Agriculture Conference (GGAA)
Number of pages1
Publication yearJun 2022
Pages244
Publication statusPublished - Jun 2022
Event8th International Greenhouse Gas & Animal Agriculture Conference - Orlando, United States
Duration: 5 Jun 20229 Jun 2022
https://conference.ifas.ufl.edu/ggaa/index.html

Conference

Conference8th International Greenhouse Gas & Animal Agriculture Conference
LandUnited States
ByOrlando
Periode05/06/202209/06/2022
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