Location: Forage and Livestock Production Research2009 Annual Report
1a. Objectives (from AD-416)
The long-term objective of this project is to determine the feasibility of producing grass-fed beef in the Southern Great Plains and resolve the major constraints to finishing cattle on forages. If it is not possible to produce beef with 100% forage inputs, then we will develop systems that utilize more forage inputs to lessen our dependence on feed grains, increase revenues to local rural communities and small farmers, and produce more beef under free range conditions that appeal to the socially conscious consumer. In some cases, we will use sheep as a ruminant model to rank forages based on nutritional qualities, determine the impact of dietary supplementations on forage digestibility and protein metabolism, and the effect of genetics on forage intake and utilization. Over the next 5 years we will focus on the following specific objectives: Objective 1: Design, install, and evaluate, year-long forage-based livestock production systems that include multiple forage species to fill the forage deficit gaps in the spring and fall. Sub-objective 1.A. Develop year-long forage-based livestock production systems utilizing perennial cool-season forages and annual and perennial warm-season forages. Sub-objective 1.B. Determine the most efficient combination of beef cattle genotypes and forage-based production systems. Sub-objective 1.C. Determine the impact of maternal influence on postweaning performance of cross-bred calves from two-breed cross cows where calves are managed under two postweaning systems to enhance the efficiency of finishing cattle on pasture. Objective 2: Define and develop management strategies to mitigate nutrient imbalances that limit the production of grass-fed beef by year-round grazing systems developed for the southern Great Plains. Sub-objective 2.A. Compare the digestibility and N utilization of perennial cool-season grass species that may be used to fill-in the forage deficit gaps in a multiple forage species production system used to produce grass-fed beef. Sub-objective 2.B. Determine if energy or protein limits average daily gain (ADG) of calves grazing warm- and cool-season grasses under short-duration intensive-stocking management as part of a system to produce grass-fed beef. Sub-objective 2.C. Determine low-cost supplementation for stockers grazing cool-season and warm-season forages to approach genetic potential for postweaning stocker gains in purebred and crossbred stocker lambs. Sub-objective 2.D. Develop methodology to determine forage intake using forage canopy spectral reflectance and evaluate genetic effects for forage intake and efficiency of forage utilization.
1b. Approach (from AD-416)
Stocker calves of different breed types will be used to determine the interaction between breed type and intensity of livestock management on the rate and efficiency of body weight gain. Combinations of warm- and cool-season forage resources will be evaluated as components of a year-round grazing system. Nutrient imbalances that limit efficiency of beef production on pasture will be identified and management practices to mitigate these imbalances will be developed. New methodology to determine nutrient intake of grazing animals will be developed to give pasture managers a new tool to aid in their decision making process.
3. Progress Report
Knowledge of maternal performance during the preweaning period is important in the development of integrated cow-calf and stocker production systems. Research at the Grazinglands Research Laboratory was conducted to determine milk production and milk quality for different tropically adapted and temperate sire breeds mated to Brangus cows. Milk yield, milk fat, and somatic cell count were evaluated for 4 calf crops in Bonsmara-, Brangus-, Charolais-, Gelbvieh-, Hereford-, and Romosinuano-sired cows from Brangus dams. Differences in milk yield were negligible among cows sired by Bonsmara, Charolais, Gelbvieh, Brangus, and Hereford bulls while cows sired by Romosinuano bulls gave substantially less milk than the other breed groups of cows. Milk fat concentration for Romosinuano-sired cows was greater than milk fat concentration from other breed groups, except Bonsmara- and Hereford-sired cows. Somatic cell count, an indicator of mastitis, a disease that decreases milk production, was less in Romosinuano-sired cows. The lack of differences in milk yield among five of the breed groups may be indicative of nutritional limitations of the pasture grazed by these cows, while the lower milk yield and somatic cell count in the Romosinuano-sired cows suggests possible lower maintenance requirements and disease resistance in this breed group. Excess perennial cool-season grass production can be harvested as hay for feeding later. A series of experiments were conducted to estimate dry matter intake (DMI) and digestibility of hay from perennial cool-season grass pastures relative to hay made from an annual cool-season grass pasture. In experiment 1, wheat (Triticulm aestivum Var. Pioneer 2174), tall wheatgrass (Elytrigia ponticum Var. Jose), smooth brome (Bromus inermis Var. Lincoln), and intermediate wheatgrass (Thinopyrum intermedium Var. Manska) were harvested in the spring as high moisture hay and fed to lambs. Apparent digestibility of the dry matter and fiber fractions and DMI were not different (P > 0.10) among the hays used in this experiment. In experiment 2, grasses were harvested as field dried hay from established stands of Jesup Max Q (Festuca arundianaceace) and Nanyro (Festuca arundianaceace) tall fescues, Harusakae meadow fescue (Festuca pratensis), and wheat (Var. Pioneer 2174). Lambs fed wheat hay had greater (P < 0.05) DMI (69.3 g/kg BW0.75, respectively) compared to lambs fed Jessup or Nanyro (35.0 and 33.8 g/BW 0.75), while lambs fed Harusakae hay had intermediate DMI (50.2 g/BW 0.75). Digestibility of Jesup hay was greater (P < 0.05) than the other three hays. Excess cool-season grasses can be harvested as high moisture or field-dried hay, but harvested hays had greater concentrations of ADF and NDF and a lesser concentration of N than pre-harvest standing forage.
1. High levels of milk production potential in beef cows not sustainable on native tall grass pasture: Beef cow-calf producers strive for heavier calf weaning weights to increase gross income from each cow. Because greater milk production by the cow results in heavier weaning weight, producers make genetic selections to increase cow milk production. A scientist in the Forage and Livestock Production Research Unit in El Reno, OK, measured milk production in beef cows of different ages and breed types that varied in genetic potential for milk production. Studies indicate that native grasses used to supply the nutrients for milk production are not adequate enough to support genetic potential for high milk yields and that to be efficient producers must match the cow's genetic potential for milk production with available nutrient supply. These findings led him to evaluate the utility of a new breed from South American, Romosinuano, for beef cattle production in the U.S. This breed was found to have the correct balance of nutrient requirements, milk production and udder health to fit with the production environment of the southern Great Plains.
2. Keeping grass-fed beef gaining when forage production is limited: Harvesting available forage that is excess to the needs of grazing-livestock and storing it for feeding later to fill gaps between forage production cycles is used routinely by producers. This practice is essential in production systems that are designed to produce grass-fed beef. Within a grass-fed beef production enterprise, producers can substitute perennial cool-season grasses for annual cool-season grass to reduce annual crop establishment cost and still have high quality forage for grazing livestock. Scientists in the Forage and Livestock Production Research Unit in El Reno, OK, determined the nutritional value of excess perennial cool-season perennial forages harvested as field dried or high moisture hay. Their studies indicate that perennial cool-season grasses recommended for inclusion in a diverse forage-livestock production system can be harvested as high moisture hay and as dry hay, and that the hay has good nutritional value. Producers of grass-fed beef can use these hays during periods of drought or during the winter when grazing on pasture is not practical.
5. Significant Activities that Support Special Target Populations
Research under this project is conducted in close collaboration with the staff of Langston University, a 1890s university located at Langston, OK, and the scientists of the Grazinglands Research Laboratory who are permanently stationed at Langston University (project 6218-12210-003-00D). That research project addresses the unique problems encountered by small, minority, and socially disadvantaged/limited resource forage and livestock producers. During the fiscal year, scientists stationed at El Reno worked closely with faculty and students at Langston University to provide training, grant-writing assistance, and research experiences. A field tour for the Farming with Grass Conference Participants and other stakeholders highlighted key technologies developed at the Grazinglands Research Laboratory that enhance efficiency, reduce environmental and economic risks, and promote sustainability of mixed crop-forage-livestock agricultural systems. About 200 persons, including numerous small to medium size producers, extensionists, and conservationists, participated from over 30 states participated in the tour.