Location: Forage and Livestock Production Research
2018 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
A barn housing the GrowSafe Cattle Feeding System which uses advanced technology to collect research data related to feed intake and feed efficiency is functional. Pasture-based grazing using various forages for backgrounding and finishing beef cattle were completed (Objective 1). Weight gain, carcass parameters, and meat quality when beef cattle were finished on pasture was compared to beef cattle contemporary groups finished on high concentrate (corn diets) (Objective 1, Sub-objective 1A). During the finishing period, cattle on concentrate averaged 3.0 pounds per day gain while those finished on alfalfa pasture averaged 2.25 pounds per day gain. 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. ARS researchers at Grazinglands Research Laboratory in 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. Rumination time does not appear to be related to feed efficiency, but may be related to genetics. A new standard cooperative agreement was established with researchers at Texas A&M AgriLife Research at Vernon, Texas to expand rumen microbiome research efforts related to cow size nutrient-use efficiency (Objective 1, Sub-objective 1C). 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 the Genetics, Breeding, and Animal Health Research Unit at Clay Center, Nebraska and the Range and Livestock Unit at Miles City, Montana will be initiated in the fall 2018 (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, especially related to grazing and high forage based diets in order to evaluate genetics x management x production environment interactions.
Accomplishments
1. Effect of frame size on enteric methane and carbon dioxide production in lactating angus cows grazing native tall-grass prairie in central Oklahoma: Summer season. Methane gas has been suggested to be one of the major greenhouse gases, thus being a major contributor to global warming. In ruminants, enteric methane is a necessary byproduct of fermentation within the symbiotic relationship between rumen microbes and the ruminant host. The most efficient cow size for use in grazing systems has long been debated. Large-frame cows weighed 128 kg more and weaned a calf that was 39 kg heavier than medium-framed cows. There was no difference in amount of cow methane or carbon dioxide produced during the summer per kg of calf weaned. This finding suggests that both cow types are equally efficient at producing calves relative to enteric greenhouse gas production. Further research is needed to evaluate the impact of cow frame type on enteric gas production during other seasons of the year. Information will benefit cattle producers and researchers selecting and breeding cattle to be more economically efficient for reproductive performance.
