Location: Forage and Livestock Production Research2015 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 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. Initial soil nutrient flux using plant root simulator probes has been completed in native prairie pastures managed with continuous and rotational stocking of beef cows. Additional soil nutrient flux measurements are planned for native prairie pastures (one acre and one-half acre) using mob grazing (high density cow stocking) for only 24-h periods. Additional soil nutrient fluxes will be collected in a newly initiated project utilizing native prairie pastures managed with spring prescribed burning followed by various intensities of grazing by beef cattle to evaluate long-term effects on pasture ecological parameters. Establishment/increase of cow herd numbers continues. The 2014 calves are on finishing treatments and carcass data will be collected later this year. Enteric methane production is being measured throughout the year from individual cows (small and large frame) in a herd grazing native prairie pasture. A second Long-Term Agroecosystem Research (LTAR) flux tower was deployed into a no-till wheat field which is part of the new long-term research crop and livestock production systems farm. Wheat and canola pasture treatments will be established in Fall 2015. Three research beef cattle finishing barns were destroyed in May 2011 by a tornado. One barn has been restored and the Calan gate system retrofitted; there is still a reoccurring problem with the gutter flush and waste pump for the lagoon. A group of heifers was evaluated for intake and nutrient-use efficiency using the Calan gate system in the spring 2015 (data is being analyzed). A study to evaluate intake and nutrient-use efficiency in steers differing in frame score/size and finished on high grain diets has been initiated (June 2015). A second group of steers differing in frame score/size finished on an alfalfa-hay diet will be initiated in the fall 2015 do determine intake and nutrient-use efficiency. All steers will have carcass data and meat quality data evaluated. A second barn has been erected and currently being retrofitted with pens and a GrowSafe feeding system for cattle; this system will be used to also determine nutrient-use efficiency in beef cattle.
1. Cow breeding programs for resilience to variable climate. The relationships of calf preweaning gains to dam milk yield and quality may not be the same for all breeds of beef cattle. Scientists at El Reno, OK and collaborators at the University of Arkansas, Fayetteville, AR, and Gansu Agricultural University, China determined calf preweaning gains based on milk yield and quality in cows sired by Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano breed groups, all from Brangus dams. Increases in milk traits beyond a maximum effective level in European breed types, such as Charolais and Gelbvieh, do not always result in improvements in calf performance. Increasing milk traits in Herefords and tropically-adapted breed types has the potential to increase calf preweaning performance, within the range of the data of this study. Information can be useful in refining beef cattle breeding and production programs for better resilience to variable climate.
2. Pasture-finished meat-goat kids and lambs fit niche markets in the USA. Increased ethnic diversity in the USA has increased the demand for goat meat. There is also an increasing demand for low-fat, red meats across the broad spectrum of the USA population. Scientists at ARS, El Reno, OK along with colleagues at Michigan State University, East Lansing, MI and The Ohio State University, Columbus, OH finished meat goats on alfalfa, red clover, orchardgrass, chicory, or birdsfoot trefoil pastures. Overall, pasture-finished goats produced desirable live weights and carcass weights for most niche markets in the USA. Fat content and desirable fatty acids in these meats fit the guidelines for lowering fat and improving nutrition in human diets and health.
Turner, K.E., Cassida, K.A., Zerby, H.N., Brown, M.A. 2015. Carcass parameters and meat quality in meat-goat kids finished on chicory, birdsfoot trefoil, or red clover pastures. Meat Science. 105:68-74.
Neel, J.P., Felton, E.E., Singh, S., Sexstone, A.J., Belesky, D.P. 2015. Open pasture, silvopasture, and sward herbage maturity effects on nutritive value and fermentation characteristics of cool-season pasture. Grass and Forage Science. doi: 10.1111/gfs.12172.
Duckett, S.K., C., F., G, V., M., M.C., Neel, J.P., Ron, L.M., William, S.S., Fontenot, J.P. 2014. Effect of frame size and time-on-pasture on steer performance, longissimus muscle fatty acid composition and tenderness in a forage-finishing system. Journal of Animal Science. 92:4767-4774.
Turner, K.E., Cassida, K.A., Zerby, H.N. 2014. Meat goat kids finished on alfalfa, red clover, or orchardgrass pastures: Carcass merit and meat quality. Meat Science. 98:629-636.