Location: Rangeland Resources & Systems Research
Project Number: 3012-21500-001-019-I
Project Type: Interagency Reimbursable Agreement
Start Date: Apr 15, 2024
End Date: Aug 31, 2031
Objective:
Objective 1: Evaluate the role of grazing strategies and their influence on forage quality to affect livestock enteric methane emissions in a grazing setting in both shortgrass steppe and northern mixed-grass prairie (RRSRU).
Objective 2: Evaluate the role of livestock genetics on livestock enteric methane emissions in a grazing setting in both shortgrass steppe and northern mixed-grass prairie (RRSRU).
Approach:
The RRSRU has available cattle from private producers to conduct grazing experiments during the grazing season (May – October). Cattle provided at both research sites either already have been DNA tested or can be for genetics. Animal handling facilities are available for individual animal weight gains. At the Central Plains Experimental Range, yearling cattle can graze on invaded (cheatgrass-dominated) paddocks, shortgrass (blue grama-dominated on loamy soils), taller C3 mixed grass (needleandthread-dominated on sandy soils), shrub (saltbush), and saline vegetation communities (dominated by inland saltgrass). At the High Plains Grasslands Research Station, replacement heifers and/or 2- and 3-year old cows can graze on invaded (cheatgrass-dominated) paddocks, shortgrass (blue grama-dominated on loamy soils), taller C3 mixed grass (needleandthread-dominated on sandy soils), improved forages (mostly bromegrass and crested wheatgrass), and subirrigated vegetation communities (dominated by timothy and other introduced hay-type grasses). In Objective 1 and 2, and the tasks within, enteric CH4 and CO2 emissions and O2 consumption will be measured using the GreenFeed enteric methane systems (GEMS). When the animal visits the GEMS and a visit is allowed, the GEMS dispenses a pelleted bait supplement at intervals set by the researcher. The sensors will be calibrated weekly using the calibration gases provided by C-Lock inc. Weekly fecal samples from grazing animals will be collected from grazing animals and sent to the Grazingland Animal Nutrition laboratory (GANlab) for crude protein and digestible organic matter.
In all experiments, individual animals will be the experimental unit. All statistical analysis will be conducted using the R software (R Core Team, 2021). The models will be generated using the ‘lmer’ function of the ‘lme4’ package. The GEMS unit that the animals are using will be included in the model as a random effect and the dietary treatment will be included as fixed effects. Statistical significance will be considered at P = 0.05 and tendencies will be considered at 0.05 < P = 0.10.
