Location: Forage and Livestock Production Research2011 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
The project evaluating combinations of beef cattle genotypes and forage-based productions systems was continued in FY11 with six cow breed groups managed under two preweaning management systems and two postweaning management systems. Cows were bred to eight Angus sires to produce the 2011 calf crop, and breeding was completed for the 2012 calf crop. Postweaning and carcass data was collected on the 2009 calf crop, and preweaning and postweaning data was collected on the 2010 calf crop. The project evaluating the impact of maternal influence on postweaning performance was continued, with milk production and quality measurements taken in 2011 as well as evaluation of mastitis and milk fatty acid composition in the six cow breeds to provide more basic information in interpretation of milk yield and quality on postweaning performance. Three years of forage intake data in a diallel experiment with Katahdin, Suffolk, and reciprocal-cross lambs was analyzed and a manuscript was prepared. A fourth year of forage intake data in this diallel was also done to provide more precision.
1. Efficiency of forage utilization in hair and wool lambs. Knowledge of both forage quality and intake is critical in the determination of the need for supplementation of animals on forage. Forage intake has been particularly difficult to estimate, and little is known about genetics of forage intake. ARS scientists at El Reno, OK, conducted a study to evaluate genetic effects of and predict forage intake in Katahdin, Katahdin x Suffolk, Suffolk x Katahdin, and Suffolk lambs. Intake was highest in the Suffolk x Katahdin and Katahdin ewe lambs compared to Katahdin x Suffolk and Suffolk lambs. There was evidence for genetic effects in favor of lambs from Katahdin ewes. Efficiency of forage utilization was better in lambs from Katahdin ewes. These results provide information to facilitate the use of genetic effects in the development of efficient grazing systems and precision supplementation.
2. Improving profitability in feedlot cattle. Profitability in the postweaning phase of most livestock operations is largely dependent on the efficiency of feed utilization into suitable consumable products such as meat. There is a need to improve production efficiency by matching animal needs for production (genetic potential) with resource availability and allocation (feed quantity and quality), and through adequate choices of feed ingredients for least-cost programs. ARS scientists at El Reno, OK, in collaboration with Gansu Agricultural University in China, conducted a simulation study to evaluate efficiencies of medium-frame and large-frame feedlot cattle fed with rations balanced by least-cost programming. When feed resources were limiting, medium-frame cattle were more efficient than large-frame steers but large-frame steers were more efficient when feed resources were abundant. When the choices of ration ingredients for protein, energy, and roughages were reduced to a smaller number to reflect choices that might be more locally available (corn grain was included in both sets of ingredients), net returns were substantially reduced compared to where a larger set of ingredients were available. The results allow more appropriate matches of animal genetics to feed environment to increase efficiencies in the production of finished cattle.
Wan, H.L., Zhang, L.P., Brown, M.A., Wu, X.J., Wang, J.H., Wu, J.P. 2011. Influence of aging days and age at harvest on the meat quality characteristics of Gannan black yak. Journal of Animal and Veterinary Advances. 10(9):1089-1096.