Location: Forage and Livestock Production Research2016 Annual Report
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.
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.
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 (Objective 3). Information will be used to determine the cause of depressed gains when cattle graze Jose tall wheatgrass compared to wheat pasture. Productivity of beef cattle and pastures continues to be measured in various projects. Soil nutrient flux measurements were collected from native prairie pastures (one acre and one-half acre confinement areas) using mob grazing (high density cow stocking) for only 24-h periods (Objective 1). Additional, soil nutrient fluxes were 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 native grassland ecological parameters. A second intensive field campaign was conducted to determine fecal output, forage digestibility, and methane production from small- and large-frame beef cows grazing native grassland during a period of declining forage quality in Oct and Nov 2015 (Objective 1). Establishment/increase of cow herd numbers continues. The 2015 calves are on finishing treatments and carcass data will be collected later this year (Objectives 2 and 3). Enteric methane production is being measured throughout the year from individual cows (small and large frame) in a herd grazing native prairie pasture (Objective 1). A Long-Term Agroecosystem Research (LTAR) farm using till and no-till wheat fields to research crop and livestock production systems continues; wheat and canola field treatments were established in fall 2015 and grain harvest data completed in summer 2016; the next sequence of field treatments will be established in Fall 2016 (Objective 1). Three research beef cattle finishing barns were destroyed in May 2011 by a tornado; the Calan gate barn has been restored and functional in spring 2015; a second group of heifers was evaluated for intake and nutrient-use efficiency using the Calan gate system in the spring 2016 (data is being analyzed(Objectives 2 and 3). A study to evaluate intake and nutrient-use efficiency in a second group steers differing in frame score/size and finished on high grain diets has been initiated (June 2016; Objectives 2 and 3). A second group of steers differing in frame score/size finished on an alfalfa-hay diet will be initiated in the fall 2016 do determine intake and nutrient-use efficiency. All steers will have carcass data and meat quality data evaluated (Objective 2). A second barn destroyed in the 2011 tornado 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 (Objective 2 and 3).
1. Management options for lambs and meat-goat kids on pastures in the U.S. In the U.S., lamb and meat goat production is growing rapidly to supply animals for many ethnic markets. However, internal parasite control is a significant management challenge for producers. Scientists at ARS, El Reno, Oklahoma along with colleagues at West Virginia University, Morgantown, West Virginia; Michigan State University, East Lansing, Michigan; and Virginia Tech, Blacksburg, Virginia finished lambs and meat goats on grass-clover pastures with and without whole cottonseed supplement. Supplemented lambs and meat-goat kids had improved weight gains and animals had a better tolerance to internal parasites. In addition, using an internal parasite-resistant breed of lamb (Katahdin) and a selective deworming program of individual animals resulted in the least number of dewormer doses given to animals. Overall, information can be used to develop and refine animal selection, feeding, grazing, or pasture-finishing systems with reduced reliance on dewormers for more sustainable production of lamb and meat goats for niche markets in the U.S.
Neel, J.P., Belesky, D.P. 2015. Herbage production, nutritive value, and animal productivity within hardwood silvopasture, open and mixed pasture systems in Appalachia, United States. Grass and Forage Science. doi:10.1111/gfs.12211.
Turner, K.E., Belesky, D.P., Zajac, A.M., Dowd, M.K. 2015. Performance and blood parameters when lambs and meat-goat kids were finished on pasture with and without whole cottonseed (Gossypium hirsutum) supplementation. Grass and Forage Science. 70:451-464.
Turner, K.E., Belesky, D.P., Cassida, K.A., Zajac, A.M., Brown, M.A. 2016. Selective deworming effects on performance and parameters associated with gastrointestinal parasite management in lambs and meat-goat kids finished on pasture. Sheep and Goat Research Journal. 31:17-29.
Starks, P.J., Turner, K.E., Brown, M.A., Venuto, B.C. 2015. Canopy visible and near-infrared reflectance data to estimate alfalfa nutritive attributes before harvest. Crop Science. 56:484-494.