Location: Forage and Livestock Production Research
2022 Annual Report
Objectives
The long-term objective is to improve understanding of forage-based production systems and genetics that allow ruminant livestock to efficiently consume and convert feedstuffs, primarily forages. Specifically, during the next five years we will focus on the following objectives.
Objective 1: Evaluate nutrient-use and production efficiency in reproductive and terminal beef cattle within conventional and unconventional production systems in the Southern Great Plains (SGP).
• Sub-objective 1A: Determine the relationship between frame score and calf growth rate, carcass quality, and economic returns under different finishing systems.
• Sub-objective 1B: Evaluate traditional and novel annual grain crops for their efficacy as forages within beef production systems used in the SGP.
• Sub-objective 1C: Determine the relationship between Residual Feed Intake (RFI) evaluations conducted in growing heifers and those conducted again in the same animals as mature cows within the SGP.
• Sub-objective 1D: Characterize rumen metagenome and metabolome in relation to animal nutrient-use/production efficiency in beef cattle consuming forage and forage-grain diets.
Objective 2: Determine the impact of management and animal genetics on health and stress related indices, and beef quality.
• Sub-objective 2A: Determine the impact of finishing system (pasture versus confinement) on animal stress level indicators, and end product.
• Sub-objective 2B: Evaluate the impact of cow management system on temperament and productivity in range cows and their offspring.
Objective 3: Determine relationships between genetic/genomic characterizations in beef cattle and: a) the environmental and managerial responses, and b) the production phases.
• Sub-objective 3A: Characterize environmental, managerial, and sire impacts on production responses within contemporary groups of cattle.
• Sub-objective 3B: Evaluate the relationships between genetic markers of the rumen biome and key responses during the production phases.
Approach
Over the last 50 years, annual U.S. beef production has increased with fewer cows in the national herd by harvesting larger animals. This is due in part to availability and use of low-priced, abundant feed grains. While feed costs represent the single largest expense in beef production, less than 20% of the post-weaning feed energy consumed is converted to edible product. As competition and the price of feed grains increases due to growing global human population, use of grains for energy production, and other uses, beef production enterprises may need to transition from greater grain dependency to greater reliance on forage resources (pasture and rangeland) produced on lands not suitable for more intensive crop production. We propose to improve the efficiencies and sustainability of conventional forage-based components of beef production systems by development of more efficient management systems. In addition, identification of animal genetics best adapted to forage-based production systems in the Southern Great Plains (SGP) will aid in understanding how to reduce animal stress in management systems. The end result will be improved efficiencies of beef production with less grain and fossil fuel inputs, less need for capital through increased use of on-farm products, and increased competitiveness and profitability for producers. To accomplish this goal, the interactions of animal genetics, nutrient-use, health, and the beef system components must be understood to best match the animal resource with the forage resource. There is also a need to understand some of the ecological benefits and impacts of forage-based components of forage-based beef production systems.
Progress Report
Across all finishing treatments, smaller framed cattle had average daily gains (ADG) of 2.3 pounds per day while larger framed cattle had 2.5 ADG. Larger frame cattle also had heavier carcasses, equating to more salable product per head. Frame size and finishing diet did not impact beef tenderness (Objective 1, Sub-objective 1A). ARS researchers at El Reno, Oklahoma, and university collaborators began investigating the capacity of a range of underutilized grain crops from India, the Middle East, Africa, Central and South America for their capacity to grow in the southern Great Plains and provide high quality forage (Objective 1, Sub-objective 1B). The final group of heifers for evaluation of residual feed intake was completed (Objective 1, Sub-objective 1C). Feed intake, rumination time, and weight gain were measured in beef heifers differing in frame size to better understand feed- and nutrient-use efficiency for identifying and selecting the type of beef animal more adapted to the production environment of the Southern Great Plains. Heifer frame size did not appear to influence feed efficiency on a forage diet. Observations and measurements related to stress level indicators (Objective 2, Sub-objective 2A) in confinement- and pasture-finished beef cattle, and beef animal temperament (Objective 2, Sub-objective 2B) in pasture studies were initiated. A new collaborative research project plan with ARS research at Clay Center, Nebraska, and Miles City, Montana, was initiated in the fall 2018 and continued for 4 years (Objective 3). This project integrates novel genomic approaches to enhance knowledge of the bovine genome, improve genetic merit of purebred and crossbred beef cattle, and improve beef cow energetic efficiency to account for genetics x management x production environment interactions. ARS researchers in El Reno, Oklahoma, and university collaborators investigated the capacity of a range of underutilized grain crops from India, the Middle East, Africa, Central and South America for their capacity to grow in the southern Great Plains and provide high quality forage (Objective 1, Sub-objective 1B). ARS researchers at El Reno, Oklahoma, in collaboration with researchers at Oklahoma State University, continued a 4-stage experiment to test the capacity of cultivars of novel (to the United States) grain legumes and cereal grasses to produce forage, and their forage value to cattle. The first stage of the Sub-objective 1B was completed (fiscal year (FY) 2018), and stage 2 (FY2019) in the second of three years. Preliminary results noted a number of grain legume and grass cultivars from regions in Africa, India, Arabian Peninsula, Pakistan, and Afghanistan with large capacities to produce high quality forage in Oklahoma during late summer. Under a Standard Cooperative Agreement with researchers at Texas A&M AgriLife Research at Vernon, Texas, a Post-Doctoral Research Associate was hired to begin rumen microbiome research efforts related to cow size nutrient-use efficiency (Objective 1, Sub-objective 1D). Research continued to evaluate the impact of cow management systems on temperament and productivity in range cows and their offspring (Objective 2, Sub-objective 2B) with second year data collection occurring on schedule. In FY20 (Objective 1, Sub-objective 1A) the valuation of finishing system using forages continued. For Objective 1, Sub-objective 1B, there were no milestones to be reported in FY20; however, several of the projects in this Sub-Objective 1B were ahead of schedule. The goal was to search for functional annual forages for the Southern Great Plains among novel annual legumes and grasses that are traditionally grown for grain in order to identify species or cultivars that can provide high quality forage for improved animal performance during the summer grazing season. ARS researchers at El Reno, Oklahoma, with collaborators at Oklahoma State University, continued to test the capacity of cultivars of novel (to the United States) grain legumes and cereal grasses to produce forage, and assess their forage value to cattle. The second stage of the Sub-objective (1B.2) was completed (FY2020), and samples were prepared to examine the function of these novel forages in the rumen of cattle, as part of Stage 3 (1B.3). Scientific papers compared the capacity of the novel legumes guar and tepary bean to serve as high quality forage during late summer. Other research reported on combining near infrared reflectance spectroscopy and machine learning techniques to improve the definition of different attributes of forage quality in four legumes. Under (Objective 1, Sub-objective 1 D), an agreement with researchers at Texas A&M AgriLife Research at Vernon, Texas, a Post-Doctoral Research Associate continued rumen microbiome research efforts related to cow size and nutrient-use efficiency. A grazing project was initiated to monitor changes in rumen microbiome ecology during the growing season as steers graze a native warm-season grass pasture that was controlled burned in the spring. For (Objective 2, Sub-objective 2A), research continued to evaluate confinement- and pasture-finishing impacts on animal stress (cortisol) during the finishing period while for (Objective 2, Sub-objective 2B) research continued to evaluate the impact of cow management systems on temperament and productivity in range cows and their offspring. For (Objective 1, Sub-objective 1A), evaluation of finishing system using forages continued, although all animals were finished on pasture; the feedlot component was not conducted due to the extremely high corn and commodity prices for the rations needed and the uncertainty of packer availability to collect carcass data for FY21 due to COVID-19 concerns. Under Objective 1, Sub-objective 1B, ancillary research focusing on different remote sensing techniques for nitrogen (and crude protein) in novel forages, and another on modelling to identify management for optimal production of forage soybean and winter wheat in intensive, double-cropped rotations under the sub-objectives were conducted ahead of schedule. For (Objective 1, Sub-objective 1C), a third year evaluating cow residual feed intake (RFI) was initiated, but not completed due to ration adaptation issues. And subsequently (Objective 1, Sub-objective 1 D) a third year evaluating the rumen microbiome of the RFI cows was not completed as a result of animals not adapting to the diet as planned. Under an agreement with researchers at Texas A&M AgriLife Research at Vernon, Texas, a grazing project was completed to monitor changes in rumen microbiome ecology during the growing season as steers grazed a native warm-season grass pasture that was controlled burned in the spring. Samples were sent for analyses at Texas A&M University. For (Objective 2, Sub-objective 2A), research continued to monitor beef animal stress (cortisol) during growing and finishing phases and for (Objective 2, Sub-objective 2B), the cow management on temperament and productivity project has been completed.
Accomplishments
1. Quantifying fluxes of carbon, energy, and water of winter wheat managed as pasture. An understanding of the movement of carbon, water, and energy among the different components of the soil-plant-animal-atmosphere interface is important to describing the function of these agroecosystems. ARS researchers at El Reno, Oklahoma, undertook a study from data generated by 8 eddy covariance systems applied to pastures of winter wheat managed for different harvestable crops. Continuous year-round data were collected from replicate pastures of winter wheat managed under grain only (control), winter grazed and summer grain harvest, and graze-out by yearling stocker cattle. High levels of variability occurred within and among seasons in the magnitudes of carbon dioxide fluxes, net energy exchange, and evapotranspiration of soil water, in all wheat fields regardless of form of management. Carbon, energy, and water budgets were generally larger under grain only production (control), followed by graze-grain and graze-out wheat. However, pastures of winter wheat were large sinks of carbon dioxide during growing seasons across all forms of pasture management. Information developed from this research will provide tools land managers can apply to improve forage production by wheat pasture.
