Location: Forage and Livestock Production Research2014 Annual Report
1a. Objectives (from AD-416):
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, in profitable production systems while mitigating negative impacts on the environment. Specifically, during the next five years we will focus on the following objectives. Objective 1: Determine how forage livestock production systems interact with plants, soils, and climate with respect to carbon and nitrogen cycling under forage and grazing systems typical for the southern plains. Sub-objective 1A: Evaluate continuous and management intensive rotational grazing systems on native prairie pastures and quantify cow-calf production traits, animal and plant productivity, input requirements, and carbon (C) and nitrogen (N) dynamics in the soil-plant-animal-atmosphere continuum. Sub-objective 1B: Determine greenhouse gas (GHG) emissions from soil, plant, and animal components of diverse grazing systems. Objective 2: Determine the most efficient ruminant genetic types for forage-based production systems to optimize forage use efficiency. Sub-objective 2A: Determine how frame score affects calf growth rate, carcass quality, and economic returns under different finishing systems. Sub-objective 2B: Evaluate growing and finishing systems for impact on growth rate, carcass quality, and economic returns for sheep of different genetic types. Objective 3: Evaluate feed intake and nutrient use efficiency of beef cattle fed diets varying in proportions of forage and grain in varying environments. Sub-objective 3A: Determine the effect of frame score on intake and feed efficiency of growing cattle in different seasons. Sub-objective 3B: Determine the effect of frame score and dietary metabolizable energy density on intake and feed efficiency of mature cows. Sub-objective 3C: Determine intake, diet nutritive value, and growth rate of stocker calves grazing cool-season annual and perennial forages. Objective 4: Improve breeding and management decisions by characterizing current genetic and phenotypic variation within and between predominant beef breeds and crosses using novel genomic and genetic evaluation technologies and identify novel genomic variants to optimize forage based production efficiencies for beef cattle within and across diverse physical environments in the US Great Plains.
1b. Approach (from AD-416):
The research will focus on improving production efficiency while mitigating the environmental impact of forage-livestock systems by matching animal genetic type to the proper production and nutritional regime. For objective 1), two farm-scale replicates of two grazing systems on tallgrass prairie are used to evaluate the long-term impacts of grazing system on input costs, animal performance, rangeland health, soil ecological function, and plant diversity. Grazing systems consist of continuously and rotationally grazed under an adaptive management framework. Animal production, forage biomass and species diversity will be monitored. Angus:Brahman F1 cows bred to Charolais bulls will constitute the grazing cow herd. Greenhouse gas (GHG) emissions will be monitored on: 1) native tallgrass prairie and 2) wheat pasture. Eddy covariance flux towers will be established in each pasture type to calculate CH4, CO2, water, and energy fluxes. Cattle position will be monitored using global positioning devices. Differences in GHG production with and without cattle will be determined. Simultaneously, forage intake, diet digestibility, and methane emissions will be determined using marker systems on a select group of individual animals to assess components of efficiency at the animal scale. Under objective 2, research will be conducted to match finishing system with cattle genetics to optimize biological, economic, and ecological efficiency. Frame score, associated with rate of maturity and reproductive efficiency, will be used to characterize different genetic types. At weaning, calves from each frame score class will be assigned to one of two postweaning treatments: 1) conventional (wheat pasture followed by feedlot), and 2) extended forage followed by a short feedlot phase (30-50 days) if needed]. When finished, calves will be harvested; carcass data, Warner-Bratzler shear, sensory by a trained panel, and fatty acid profile will be determined. Under objective 3, all replacement heifers, and some companion steer herd mates, will be evaluated for feed efficiency at weaning. They will be fed forage-based diets to achieve 1 kg/d gain, and individual daily intake and weight gain will be recorded. After the heifers reach maturity they will again be evaluated as mature, non-lactating cows (5 years of age). Cows will be fed a ration based on Bermudagrass baleage at maintenance for 84 d, weighed at 14-d intervals, and after final body weights are recorded on day 84, offered ad libitum access to the same ration. Efficiency will be determined as the difference in requirements and feed consumed and related to productivity during the first four calf crops. Under objective 4, research will be coordinated with the Range and Livestock Unit at Miles City, MT, and the Genetics, Breeding, and Animal Health Research Unit at Clay Center, NE. Sample collection and analysis protocols will be developed collaboratively. Novel genomic approaches will be used 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.
3. Progress Report:
Productivity of beef cattle and pastures continues to be measured in various projects. Laboratory analyses are being conducted on samples collected from three field studies to determine intake by beef steers grazing pastures of Jose tall wheatgrass or wheat. Information will be used to determine the cause of depressed gains when cattle graze Jose tall wheatgrass compared to wheat pasture. Establishment/increase of cow herds continues. The 2013 calves are on finishing treatments and carcass data will be collected later this year. Enteric methane production was measured from individual cows in a herd grazing native pasture. The first mobile LTAR tower had been deployed to the wheat pasture. A second LTAR tower is planned once a no-till wheat field has been established this fall 2014. Three research beef cattle finishing barns were destroyed in May 2011 by a tornado. One barn has been restored, and the Calan headgates retrofitted and is now suitable for measuring individual feed intake by cattle, and will be available this fall (2014) when the calves are weaned.
1. National Research Council (NRC) model poorly predicts intake by grazing beef cattle. The current 2000 NRC model for predicting intake by grazing beef cattle was an improvement over previous models; however, refinement is needed to improve prediction capability. A broad-based database was used to develop new equations for consideration for inclusion in the new NRC model. These new equations to predict intake should help the new NRC model be more robust in its ability to account for the wide variation in cow environment, dietary characteristics, and metabolic demands. Improved modeling in beef systems allow researchers, extension personnel, and producers to refine current feeding and supplementation regimens in the USA to be more nutrient-use efficient, economical, and profitable.
2. Grazing management and forage species improves performance and resilience to gastro-intestinal parasite infection in meat goats. Meat goat performance and production efficiency are reduced with high gastrointestinal overloads, especially Haemonchus which causes anemia. ARS scientists at El Reno, Oklahoma, along with a collaborator at Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, used intensive grazing management in alfalfa, red clover, or orchardgrass pastures to produce and maintain forages with high nutritive value for finishing meat goats. Weight gain by meat goats finished on alfalfa and red clover were higher and less affected by high gastrointestinal parasite loads than goats finished on orchardgrass. Overall, meat goats pasture-finished on alfalfa, red clover, or orchardgrass had ending body weights desired by most niche livestock markets in the USA.
3. Pasture-finished meat-goat kids and lambs fit niche markets in the USA. Information is limited that support on-farm and consumer decision-making as related to finishing sheep and meat goats on pasture and meat quality. Scientists at ARS, El Reno, OK along with colleagues at West Virginia University, Morgantown; Michigan State University, East Lansing; and The Ohio State University, Columbus, reported that meat-goat kids and Katahdin lambs finished on pasture with and without supplementation produced desirable ending body weights and carcass weights for most niche markets in the USA. Heavier pasture-finished Suffolk lambs may be better suited to finishing with supplemental feeds for traditional lamb markets in the USA. The fatty acid profiles differed among meats from Suffolk lambs, Katahdin lambs, and meat-goat kids and was impacted by whole cottonseed supplementation. Overall, the Omega-6 to Omega-3 fatty acid ratio and the polyunsaturated fatty acid to saturated fatty acid ratio in lamb meat and chevon (goat meat) were within the guidelines for meats that can aid improvements to human diets and health.
Lucas, A.S., Swecker Jr., W.S., Lindsay, D.S., Scaglia, G., Neel, J.P., Elvinger, F.C., Zajac, A.M. 2014. A study of the level and dynamics of Eimeria populations in naturally infected, grazing beef cattle at various stages of production in the mid-Atlantic U.S.A. Veterinary Parasitology. 202:201-206.
Turner, C.M., Brown, H., Brown, M.A., Steelman, D., Rosenkrans, C. 2013. Associations among heat shock protein 70 genotype, forage system, and horn fly infestation of beef cattle. Professional Animal Scientist. 29(2013):237-241.
Mays, A.R., Brown, M.A., Vontungeln, D.L., Rosenkrans, C.F. 2014. Milk production traits of beef cows as affected by horn fly count and sire breed type. Journal of Animal Science. 92(3:1208-1212.
Coleman, S.W., Gunter, S.A., Sprinkle, J.E., Neel, J.P. 2014. Beef Species Symposium: Difficulties associated with predicting forage intake by grazing beef cows. Journal of Animal Science. 92:2775-2784.
Turner, K.E., Belesky, D.P., Cassida, K.A., Zerby, H.N. 2014. Carcass merit and meat quality when Suffolk lambs, Katahdin lambs, and meat-goat kids were finished on a grass-legume pasture with and without supplementation. Meat Science. 98(2014):211-219.
Carroll, J.A., Sanchez, N.C., Chaffin, R., Chase, C.C., Coleman, S.W., Spiers, D.E. 2013. Heat-tolerant versus heat-sensitive Bos taurus cattle: Influence of air temperature and breed on the acute phase response to a provocative immune challenge. Domestic Animal Endocrinology. 45:163-169.
Sanchez, N.C., Chaffin, R., Carroll, J.A., Chase, C.C., Coleman, S.W., Spiers, D.E. 2013. Heat-tolerant versus heat-sensitive Bos taurus cattle: Influence of air temperature and breed on the metabolic response to a provocative immune challenge. Domestic Animal Endocrinology. 45:180-186.