Location: Forage and Livestock Production Research2008 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
More than 22 million acres of winter wheat are planted in the southern Great Plains each fall, and the majority of these acres are grazed by calves and lambs for rapid and cheap gains before entering the final phase of the beef and sheep production cycle. However, the nutrient composition of wheat forage is unique and requires a period of adjustment before positive body weight gains can be realized when animals are first placed on wheat pasture. Research at the Grazinglands Research Laboratory was conducted to determine the impact of length of exposure of lambs and steers to wheat forage on body weight gain and diet intake and digestibility. Lambs and steers grazing wheat forage for the first time gained body weight at a lesser rate during the first 14 days on pasture than lambs and steers that had previously grazed wheat forage. Long-term grazers were considered to be adapted to the high concentrations of soluble carbohydrates, digestible protein, and water found in wheat forage. Digestibility of wheat forage dry matter, fiber, and nitrogen components were no different between animals that had grazed wheat forage for long or short periods. Therefore, lower wheat forage intake was probably the major factor in lessening body weight early in the grazing season. To fully utilize wheat forage, transition diets could be developed to facilitate metabolic and ruminal adjustments that steers and lambs must make during the first 14 days of grazing wheat forage. (NP 101, Component 2) Knowledge of the relationship of maternal performance during the preweaning period to calf postweaning growth is important in the development of integrated cow-calf and stocker production systems. Research at the Grazinglands Research Laboratory was conducted to determine the relationship of cow milk production and calf postweaning performance and how that relationship might be affected by the sire breed of the calf and postweaning management system (drylot on mixed grain rations vs. wheat pasture grazing). Milk production of the cow during the preweaning period was an important determinant of postweaning performance, but the effect of milk on postweaning growth of the calf depended on calf sire breed and postweaning management. Generally, calf sire breed was a more important influence on the effect of milk on postweaning growth of the calf when calves were managed in drylot on mixed rations compared to wheat pasture. In drylot management, some sire breeds, such as Gelbvieh and Bonsmara, were not well-suited for use with high-milking cows, assuming the objective was to maximize calf postweaning average daily gain. Negative effects of cow milk yield on calf postweaning average daily gain were less evident on wheat pasture, although there was a trend for Romosinuano-sired calves to be penalized by higher levels of milk in their dams. To design systems to maximize postweaning productivity, careful consideration should be given to matching preweaning maternal environment to both sire breed of calf and intended postweaning management system. (NP 101, Component 2)
1. Winter feeding strategies to maximize stocker calf economic return: In the fall when beef calves are readily available, producers in the Southern Great Plains Region may purchase not only those needed for fall and winter grazing, but also extra calves to be used in the spring when more forage is available. Extra calves are usually fed hay or graze dormant warm-season grasses with supplemental protein provided. Scientists in the Forage and Livestock Production Research Unit in El Reno, OK, measured stocker calf performance and economic returns under two different winter supplementation strategies. Providing supplemental protein to calves wintered on dormant bermudagrass pastures as a self-fed liquid or limit-fed dry supplement supplements did not affect rate of gain, but the liquid supplement system used less labor. It was more economical to purchase the calves needed for spring grazing the previous fall and feed them through the winter than to wait and purchase them in spring. (NP101, Component 2)
2. Design of integrated beef production systems: Calves spend the majority of their lives in the cow-calf and stocker phases before moving into the feedlot. Cow-calf operators prefer calves that are heavier at weaning because of obvious relationships of calf weight to net income. Because of the positive relationship of cow milk yield to calf weaning weight, cow-calf operators also tend to emphasize genetic potential for milk yield in their cows. However, there is some indirect evidence that greater maternal potential in cows has detrimental effects on the postweaning growth of their calves. Balancing the milk yield of beef cows with calf performance during the postweaning period is therefore a necessary ingredient in development of efficient integrated cow-calf production and stocker production. Scientists in the Forage and Livestock Production Research Unit in El Reno, OK, measured cow milk yield and performance of calves of six sire breeds managed on two postweaning management systems. If the intended postweaning management for calves is drylot on mixed rations, Gelbvieh and Bonsmara sires should be used on cows with moderate to low milk yields while Brangus sires should be used on higher milk producing cows to maximize calf postweaning ADG. On wheat pasture postweaning management, Gelbvieh sires should be used on cows with higher milk yields and Romosinuano sires should be used on cows with low to moderate milk yields to maximize calf postweaning ADG. Calves from Hereford sires performed uniformly in postweaning ADG, independent of the milk yield of their dam or postweaning management system. It is evident that efficient integrated beef production systems will require reasonably accurate knowledge of cow herd milk production to appropriate match preweaning maternal environment, sire breed of calf and postweaning management system. (NP101, Component 2)
5. Significant Activities that Support Special Target Populations
Employees of NRCS attended a training session at GRL on June 23, 2008. Twenty three employees were from 12 states (Arizona, Georgia, Indiana, Kansas, Mississippi, Montana, New Mexico, North Dakota, South Carolina, Vermont, and Washington). By using PowerPoint presentations, oral presentations and field demonstrations, the employees learned how sustainable, environmentally friendly beef production systems developed at this location can be employed by their customer base to reduce economic risk, to increase enterprise diversity, and to add rural community economic development.
Phillips, W.A., Starks, P.J., Glasgow, S., Coleman, S.W. 2007. Different methods of estimating crude protein concentration of bermudagrass pastures for stocker calf production. Professional Animal Scientist. 23:696-701.