Nitrogen utilisation, energy utilisation and methane emissions of sheep grazing in two types of pasture

Livestock grazing plays a significant role in maintaining grasslands and promoting animal production globally. To understand the livestock performance in sown pasture (SP) vs native pasture (NP) is impor-tant to ensure more effective grassland-livestock interactions with minimal environmental impact. A 2 (treatment) * 2 (period) Latin Square design experiment was conducted with 10 growing Hu sheep # x thin-tailed Han sheep $ rams grazed perennially SP vs NP in an inland arid region of China. The objec-tives were to evaluate the effects of grazing management on nutrient digestibility, nitrogen (N) and energy utilisation and methane (CH4) emission. The N intake, N retained and energy intake (gross energy (GE), and digestible and metabolisable energy) of sheep grazing in SP were significantly increased com-pared with those grazing in NP. There were significant linear relationships between DM intake (DMI) (g/ kg BW or g/kg BW0.75) or CH4 (g/kg BW or g/kg BW0.75) emissions and forage nutrient and GE concentra-tions within each grassland type. The linear regression analysis indicated that forage CP or ether extract concentration was a good predictor for DMI (g/kg BW or g/kg BW0.75) (R2 = 0.756 or 0.752), and CH4 emis-sion could be predicted using forage nutrient and GE concentrations (R2 = 0.381-0.503). These results suggest that DMI and CH4 emissions per unit metabolic BW were accurately predicted by multiple-factor combinations of forage nutrients, including ether extract and CP paired with GE. The present out-put could provide useful information for the development of sustainable sheep grazing systems in the inland arid regions of the world.(c) 2023 The Author(s). Published by Elsevier B.V. on behalf of The Animal Consortium. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Livestock grazing is crucial for grassland maintenance and animal production worldwide. Understanding the effects of grazing on nutrient digestibility, energy utilization, and methane emissions in sown pasture vs native pasture is important for sustainable grassland-livestock interactions.