Eddy fluxes collected during 2016 to 2019 from eight production-scale multi-purpose winter wheat fields (grain only, graze-grain, and graze-out), managed under conventional till (CT) and no-till (NT), were synthesized to determine seasonality, daily magnitudes, seasonal, and annual budgets of carbon dioxide (CO2) fluxes and evapotranspiration (ET), and to investigate spatio-temporal variability of the fluxes. Maximum daily net ecosystem CO2 exchange (NEE), gross primary production (GPP), and ecosystem respiration (ER) approximated -11, 19, and 12 g C m(-2), respectively, and daily ET approximated 7 mm. Wheat fields, including graze-out, were large sinks of CO2 (ranged from -149 +/- 8 to -564 +/- 9 g C m(-2)) during growing seasons (October-May). Wheat fields, left fallow during summer, were from near neutral to large sinks of CO2 at annual (calendar year) scales. Cumulative annual NEE was up to -242 +/- 12 g C m(-2) in a NT and -183 +/- 12 g C m(-2) in a CT field, which had grain-only wheat in spring followed by graze-grain wheat in fall. Cumulative seasonal ET ranged from 260 mm to 521 mm, and maximum annual ET approximated 800 mm. In general, ET was smaller under NT than CT. Eddy fluxes showed stronger relationships with remotely-sensed enhanced vegetation index and in-situ biometric variables in grain-only fields than grazed fields. Across-site analysis for grain-only wheat showed biomass and leaf area index alone explained >80% of variations in NEE, GPP, and ET, and similar to 70% of variations in ER. Similarly, Canopy coverage explained >80% of variations in NEE and GPP, and similar to 60% of variations in ER and ET. Strong relationships of biometric observations with the fluxes demonstrated their potential to model and explain spatio-temporal variability of CO2 fluxes and ET. Results also indicated huge implications of management practices on carbon and water budgets by altering vegetative properties.

Winter wheat (Triticum aestivum L.) is a valuable crop in the southern Great Plains that grows from fall to spring, with fields then typically fallowed through the summer. Adding grazeable cover crops to the fallow period could increase farm profitability. The objective of this study was to determine eight different cover crops' nutritive value and simulated stocker calf performance. Cover crops were established in late spring 2016 and 2017 in Chickasha and Perkins, OK. At 6 wk after planting, two simulated grazing regimes based on cutting height were used: severe (<= 2.5 cm) and recommended (7.5 cm). Legumes had the highest nutritive value in comparison to warm-season grasses and grass-legume mixtures. Legumes resulted in higher simulated daily steer gain (DSG) and total steer gain per area (TSGA) values than grasses and mixtures at Perkins. At this location, legumes had superior forage nutritive value, compensating for lower yields. At Chickasha, grasses and mixtures had higher TSGA values (246.7 +/- 6.9 kg ha(-1)) and lower DSG (0.17 +/- 0.04 kg steer(-1) d(-1)) values than legumes (131.6 +/- 25.3 kg ha(-1) and 0.48 +/- 0.02 kg steer(-1) d(-1)). This finding implied that grasses and mixtures with lower individual DSG required much higher stocking rates than legumes to achieve higher TSGA values. This increment in stocking rates could increase costs, drastically decreasing profits. Consequently, legumes might be a viable option due to their balanced forage yield and nutritive value relationship. However, consideration must be given to supplemental energy to better balance the TDN/protein ratio requirements of the stocker calf.

Objective: Our objective was to determine the effects of dietary quality and protein supplementation of a low-quality warm-season grass hay on energy metabolism and methane emissions of beef steers. Materials and Methods: Eight Angus-cross steers were used in a respiration calorimetry study with a replicated 4 x 4 Latin square design. Experimental diets were (1) a low-quality forage-based diet (7.4% CP, 66.6% NDF); (2) a low-quality forage with supplemental cottonseed meal (10.0% CP, 66.3% NDF); (3) a medium-quality forage-based diet (10.5% CP, 65.0% NDF); and 4) a highquality forage-based diet (13.0% CP, 58.4% NDF). Diets were based on bluestem (Bothriochloa ischaemum) hay cut at 2 stages of maturity. Results and Discussion: Organic matter, fiber, energy, and protein digestibility and energy retention increased (P < 0.05) as the quality of the forage-based diets increased. Total methane production was not affected by diet, but methane production per unit of digested OM or energy retention decreased (P < 0.05) with increased diet quality. Protein supplementation of the low-quality grass hay increased (P < 0.05) DM, fiber, energy, and protein digestion but did not affect methane production. Methane production per unit of energy and protein retention decreased (P < 0.05) with protein supplementation. Enteric nitrous oxide emissions were minor and not affected by diet. An automated head chamber system gave average emission results similar to respiration chambers. Implications and Applications: Results demonstrate that protein supplementation of low-quality forage or increasing the quality of forage-based diets will potentially decrease the carbon-footprint of beef production.

Fields are typically kept fallow after winter wheat (Triticum aestivum L.) grain harvest in the U.S. southern Great Plains (SGP). Introducing summer cover crops to the system could increase soil conservation and farm profitability if grazed. The objective of this research was to evaluate cover crops' forage yield, residue cover potential, weed suppression, and effect on wheat production. Monocultures and grass-legume mixtures of cover crops were established in mid-June of 2016 and 2017 near Chickasha and Perkins, OK. At 6 weeks after planting (WAP), three cutting regimes based on stubble height were used: severe (2.5 cm), recommended (legumes: 7.5 cm, grasses and mixtures: 15 cm), and no cutting. Cover crops regrowth was chemically terminated at 14 WAP; winter wheat was no-till seeded in mid-October; then harvested in early-June 2017 and 2018. Cultivar Triple Treat sorghum-sudangrass [Sorghum bicolor (L.) Moench x S. bicolor var. sudanese] and grass-legume mixtures showed the greatest available forage dry matter. Grasses and grass-legume mixtures had greater forage dry matter residue and weed suppression than legumes. Results indicated that exceeding 6.4 +/- 1.2 Mg ha(-1) of total dry matter (TDM) produced during the summer, a wheat grain yield penalty of -50.1 +/- 15.8 kg ha(-1) resulted for each increment of 1.0 Mg ha(-1) of TDM produced. Also, a wheat protein content penalty of -1.9 +/- 0.5 kg ha(-1) resulted in each increment of 1.0 Mg ha(-1) of TDM produced when exceeding to 5.7 +/- 1.0 Mg ha(-1) TDM threshold. Findings suggest N uptake by high-biomass grasses and mixtures might result in deficient water and N availability for wheat production.

Abstract The Agricultural Research Service (ARS) Beef Grand Challenge is a cooperative, multidisciplinary effort evaluating differences in performance of genetic lines across production environments representative of different geographical regions. Weaned spring-born calves (n = 120 per location), representing natural service matings to Angus, Hereford, Simmental, Charolais, or indicus-composite (Beefmaster or Brangus) bulls from the U.S. Meat Animal Research Center Germplasm Evaluation program in south central Nebraska, are sent to wheat pasture (central Oklahoma) and winter range (eastern Montana), and weaned fall-born calves (n=40 per location) are sent to summer grazing on shortgrass prairie (northeastern Colorado) and southern mixed-grass rangeland (western Oklahoma). All cattle are fed a finishing ration representative of the region that approximately matches energy content across locations. Each calving season has a matching counterpart of calves that remain in Nebraska on a calf-fed drylot program (receiving ration followed by longer finishing ration). Breeds and sires are represented equally, to the extent possible, at each location. To detect differences in breed effects at each location and average over yearly variation, the study is being replicated for 4 years. Weights, stress measures, carcass composition (marbling, yield grade, quality grade, etc.), steak tenderness and steak fatty acid composition are collected from each location. Additionally, rumen metagenomic composition, metagenomic samples, preharvest food safety samples, and feed intake measures are collected at some locations. Grazing impacts and supplemental range feeding are also being evaluated. One year of sampling has been completed, with numeric differences observed for marbling and tenderness as well as growth performance among locations. Statistical differences will be evaluated when replicate years are collected. The USDA is an equal opportunity provider and employer.

This research aided in determining the impacts on rumen microbial ecology when supplemental forages and feedstuffs were added for 48 h after an initial 24-h in vitro rumen fermentation of orchardgrass (Dactylis glomerata L.) hay. Short-term shifts in bovine rumen community structure (bacteria, archea, protozoa, and fungi) resulting from each separate forage and feedstuff addition were measured using unique operational taxonomic units (OTU)s contained in terminal-restriction fragment length polymorphism (T-RFLP) profiles. The Tukey Vacuum Cleaner Analysis (TVCA) model of bacteria accounted for 66.3% of the treatment variance and OTUs clustered into 3 distinct groupings. The model developed for TVCA analysis of archaea accounted for 76.6% of the treatment variance and OTUs clustered into 2 distinct groupings. The TVCA treatment variance of protozoa accounted for 75.8% and OTUs clustered into 3 distinct groupings. Additions of various forages and feedstuffs did not result in shifts in fungal community structure in the short-term experiment. Our results demonstrate that the rumen ecology using initial T-RFLP profiles in vitro of bacteria, archaea, and protozoa and a TVCA analysis can identify pattern groupings of forages and feedstuffs. Groupings of forages and feedstuffs can help refine supplementation for improved nutritional management of ruminants.

Macronutrient (N, P, S, K, Ca, and Mg) availability and distribution in soils of grassland ecosystems are affected by diverse factors, including landscape position, climate, and forms of management. This study examined flux in plant-available macronutrients in production-scale (60 to 80 ha) paddocks of southern tallgrass prairie of central Oklahoma, United States, managed (2009–15) under two contrasting stocking methods (continuous yearlong; rotational stocking among 10 sub-paddocks). Macronutrient availability within the 0–7.5 cm and 7.5–15 cm soil depths were determined with sets of anion-cation exchange membrane probes at 16 locations within paddocks, oriented along transects from water sources to far corners. No clear overall effect related to stocking method was recorded for all macronutrient distributions. The only significant stocking method × location interaction occurred for K (p = 0.01). All other macronutrients displayed significant (p < 0.08) location effects that were common across stocking methods. Effects relatable to stocking method occurred in interactions with soil depth or time of year (p < 0.10), but responses of macronutrient flux to stocking method in these interactions varied. Higher flux occurred in available S, Ca, and Mg in proximity (<24 m) to water sources, which may be related to grazing, but local features of the landscape may also have been involved. More attention to landscape features included within paddocks, and standardized organization of water and other features within paddocks, would improve the potential to define grazing effects on macronutrient distribution.

Broad ranges of factors (parent materials, climate, plant community, landscape position, management) can influence macronutrient availability in rangeland soils. Two important factors in production-scale paddocks are the influences of location in space and land management. This study examined plant-available macronutrients (total mineral and nitrate-N, P, S, K, Ca, and Mg) in soils, with paired sets of probes (anion and cation exchange membranes) that simulate uptake by plant roots. Data were collected from sets of paddocks of southern tallgrass prairie in central Oklahoma, managed by four stocking methods during the 2015 growing season (mid-March, growth initiation by native grasses, and early-August, time of peak living plant biomass). Macronutrient availability in the 0–7.5 cm and 7.5–15 cm depths were determined at locations in close proximity to water (water tanks and 25% of the distance between tanks and paddock mid-points (PMP)), and distances near the mid-points of paddocks (70% of the distance between water and mid-points (0.7 PMP), and PMP). All of the tested stocking methods affected levels of availability of macronutrients at different times of the growing season, and among different locations within paddocks. Such responses indicated stocking methods may not result in uniform distributions of flux in plant-available macronutrients. The overall exposure of landscapes and arrangement of features within paddocks also appeared to influence macronutrient distributions.

Early warning of detrimental weather and climate (particularly drought) on forage production would allow for tactical decision-making for the management of pastures, supplemental feed/forage resources, and livestock. The standardized precipitation and evaporation index (SPEI) has been shown to be correlated with production of various cereal and vegetable crops, and with above-ground tree mass. Its correlation with above-ground grassland or forage mass (AGFM) is less clear. To investigate the utility of SPEI for assessing future biomass status, we used biomass data from a site on the Konza Prairie (KP; for years 1984–1991) and from a site at the United States Department of Agriculture-Agricultural Research Service’s (USDA-ARS) Grazinglands Research Laboratory (GRL; for years 2009–2015), and a publicly-available SPEI product. Using discriminant analysis and artificial neural networks (ANN), we analyzed the monthly timescale SPEI to categorize AGFM into above average, average, and below average conditions for selected months in the grazing season. Assessment of the confusion matrices from the analyses suggested that the ANN better predicted class membership from the SPEI than did the discriminant analysis. Within-site cross validation of the ANNs revealed classification errors ranging from 0 to 50%, depending upon month of class prediction and study site. Across-site ANN validation indicated that the GRL ANN algorithm better predicted KP AGFM class membership than did the KP ANN prediction of GRL AGFM class membership; however, misclassification rates were ≥25% in all months. The ANN developed from the combined datasets exhibited cross-validation misclassification rates of ≤20% for three of the five months being predicted, with the remaining two months having misclassification rates of 33%. Redefinition of the AGFM classes to identify truly adequate AGFM (i.e., average to above average forage availability) improved prediction accuracy. In this regard, results suggest that the SPEI has potential for use as a predictive tool for classifying AGFM, and, thus, for grassland and livestock management. However, a more comprehensive investigation that includes a larger dataset, or combinations of datasets representing other areas, and inclusion of a bi-weekly SPEI may provide additional insights into the usefulness of the SPEI as an indicator for biomass production.

The Great Plains of the USA is one of largest expanses of prairie ecosystems in the world. Prairies have been extensively converted to other land uses. The remaining prairie ecosystems are important for livestock grazing and provide benefits including habitat for avian, terrestrial, and aquatic species, carbon regulation, and hydrologic function. While producers, land management agencies, and some researchers have promoted livestock management using rotational stocking for increased production efficiency and enhanced ecosystem function, scientific literature has not provided a consensus on whether rotational stocking results in increased plant biomass or animal productivity. To address this research need, we established long-term grazing research using an adaptive management framework to encompass a wide range of production and ecological interactions on native grassland pastures. This paper describes objectives, design, and implementation of the long-term study to evaluate productivity and ecological effects of beef cow–calf management and production under continuous system (CS) or rotational system (RS) on native tallgrass prairie. Findings from 2009 to 2015 indicate that plant biomass and animal productivity were similar in the two grazing management systems. There were some indicators that forage nutritive value of standing biomass and soil nutrient content were enhanced in the RS system compared with the CS, yet individual calf body weight (BW) at weaning was greater in the CS. This prepares us to engage with producers to help determine the focus for the next phase of the research.

HighlightsEnteric methane (CH4) from beef cows on pasture was measured over three seasons using three methods.Methods yielded similar results during the summer grazing season but diverged in autumn and winter seasons.Emission averaged 0.34, 0.27, and 0.29 kg CH4 cow-1 during lactation, mid-gestation, and late gestation, respectively.Annualized enteric methane emission rate for a beef cow herd grazing tallgrass prairie was 0.32 kg d-1 cow-1.Abstract. Methane (CH4) is an important greenhouse gas, and about 20% of the carbon dioxide equivalent (CO2e) greenhouse gases emitted by U.S. agriculture are attributed to enteric CH4 produced by grazing beef cattle. Grazing cattle are mobile point sources of methane and present challenges to quantifying the enteric methane emission rate (MER). In this study, we applied three methods to measure herd-scale and individual-animal MER for a herd of beef cows grazing a native tallgrass prairie: a point source method that used forward-mode dispersion analysis and open-path lasers and cow locations, an open chamber breath analysis system (GreenFeed), and an eddy covariance ratio method that used the ratio of CH4 and CO2 mass fluxes. Three campaigns were conducted during the early season (July), late season (October), and dormant season (February). The point source and GreenFeed methods yielded similar MER (±SD) values during the early season campaign: 0.38 ±0.04 and 0.34 ±0.05 kg d-1 cow-1, respectively. However, the MER values from the two methods diverged in subsequent seasons. The GreenFeed MER decreased through the late and dormant seasons to 0.23 ±0.03 and 0.19 ±0.03 kg d-1 cow-1, respectively. In contrast, the point source MER stayed the same during the late season and increased during the dormant season to 0.41 ±0.07 kg d-1 cow-1. The CH4:CO2 ratio method, which was used only during the dormant season, yielded a MER of 0.29 ±0.05 kg d-1 cow-1. The point source and GreenFeed methods measured different MER (integrated herd-scale versus a subset of individual animals) and likely sampled methane emissions at different times during the day. We conclude that the point source method tended to overestimate emissions, and the GreenFeed method tended to underestimate emissions. Enteric methane emissions from beef cows over the three grazing seasons averaged 0.39 and 0.25 kg d-1 cow-1 as measured by the point source and GreenFeed methods, respectively. An annualized enteric MER for a beef cow herd grazing tallgrass prairie was 0.32 kg d-1 cow-1. Quantifying enteric methane emissions from grazing beef cows remains a challenge because of the mobile, often dispersed behavior of grazing cattle and the dynamic interactions of forage quality, dry matter intake, and changing physiological state of cows during the year. Keywords: Beef cows, Enteric methane, Forage quality, Grazing, Tallgrass prairie.

Low nutritive value of available warm-season grasses during July through September limits the production of yearling stocker cattle in the southern Great Plains (SGP). There has been a continual exploration of species with the capacity to provide high quality forage during summer. Mothbean (Vigna aconitifolia [Jacq.] Marechal), a short-duration, drought tolerant crop is a promising choice for the SGP. This preliminary study evaluated the potential of mothbean as a summer crop for forage, grain or green manure. Results of this study with 10 mothbean lines from a range of geographic locations suggested that crop could be harvested 100 days after planting with dry biomass yield range of 7.3 - 18.1 Mg·ha-1. Mothbean forage contained 10.8% - 14.6% crude protein (CP), 32.0% - 41.7% neutral detergent fiber (NDF), 20.7% - 29.6% acid detergent fiber (ADF), and 73% - 84% in vitro true digestibility (IVTD) at maturity. Grain yield of the 10 mothbean lines varied from 91 to 1040 kg·ha-1. The 10 tested lines generated a high amount of nitrogen (N) rich biomass at maturity with total accumulated N of 163 - 316 kg·ha-1 and a C:N ratio of 16:1 to 22:1. Overall, performance indicators suggested that mothbean has considerable potential as an alternative crop for production of forage, grain, or green manure when grown as summer crop in rotation with winter wheat. Future research should focus on evaluating mothbean within different crop settings to define its capacity as green manure or summer forage to support production of stocker cattle in the SGP.

Low forage quality of available perennial warm-season grasses during mid-summer through late summer affects the production of stocker cattle in the U.S. Southern Great Plains (SGP). Finger millet (Eleusine coracana Gaertn L.), which is a drought tolerant annual grass, could be a promising forage for the SGP. This field study assessed the adaptability and forage characteristics of 11 finger millet accessions originally sourced (1964–1981) from different parts of the world. Results of this study suggested that finger millet can generate forage yields ranging from 5.0 to 12.3 Mg ha−1 165 days after planting. Finger millet forage contained 105 to 156 g kg−1 crude protein, 598 to 734 g kg−1 neutral detergent fiber, 268 to 382 g kg−1 acid detergent fiber, 597 to 730 g kg−1 in vitro true digestibility, and 387 to 552 g kg−1 neutral detergent fiber digestibility. Ten of the 11 accessions flowered and produced grains with yields varying from 60 to 1636 kg ha−1. Overall, finger millet has the potential to serve as an alternative crop for the production of forage and possibly grain in the SGP. Further research needs to be focused on developing strategies for agronomic management and evaluating the capacity of finger millet under different grazing and hay production settings in the SGP.

Carbon dioxide (CO2) fluxes from six winter wheat (Triticum aestivum L.) paddocks (grain only, graze-grain, and graze-out) managed under conventional till (CT) and no-till (NT) systems were synthesized for the 2016-2017 growing season to compare the magnitudes and seasonal dynamics of CO2 fluxes and to investigate among-site variability of CO2 fluxes. Large variations in CO2 fluxes were observed among paddocks. Maximum daily (7-day averages) net ecosystem CO2 exchange (NEE) ranged from - 3.39 to - 8.68 g C m(-2), gross primary production (GPP) ranged from 7.33 to 16.92 g C m(-2), and ecosystem respiration (ER) ranged from 5.85 to 9.98 g C m(-2). Seasonal sums of NEE ranged from -137 to -542 g C m(-2). Optimum photosynthetically active radiation (PAR), air temperature (T-a), and vapor pressure deficit (VPD) for NEE were approximately 1700 mu mol m(-2) s(-1), 22 degrees C, and 1.25 kPa, respectively. Across-site analysis showed percent of canopy cover (Canopy%) was strongly correlated with NEE (R-2 = 0.76) and ecosystem light use efficiency (ELUE, R-2 = 0.76). Integration of PAR with leaf area index (LAI) and integration of T-a with dry biomass weight (DW) explained 81% and 74% of variations in GPP and ER, respectively. Remotely-sensed enhanced vegetation index (EVI) explained 66% and normalized difference vegetation index (NDVI) explained 69% of the variations in NEE. Integration of PAR with NDVI or EVI explained similar to 80% of variations in GPP, while NDVI x T-a explained 58% of variations in ER. Results illustrated that differences in wheat canopies related to paddock management, as indicated by differences in DW, LAI, Canopy%, NDVI, and EVI, must be accounted for explaining among-site variability of CO2 fluxes. Long-term measurements from our clustered and paired eddy covariance towers will provide insights into the effects of tillage and different grazing practices on CO2 dynamics in winter wheat.

In most pasture-based, meat-goat production systems, a major management challenge is control of gastrointestinal nematodes (GIN). Use of legumes and forbs that contain plant secondary compounds may reduce fecal egg count (FEC) expressed as eggs per g of fresh feces (epg) and/or improve overall protein nutrition to help animals better tolerate effects of GIN parasitism. This research monitored performance, FEC, FAMACHA© scores, and number of doses of dewormer administered to meatgoat kids grazing chicory (Cichorium intybus L.; CHIC), birdsfoot trefoil (Lotus corniculatus L.; BFT), or red clover (Trifolium pretense L.; RCL) pastures. Goat kids grazing RCL (68.9 g/d ± 5 g/d) had greater (P < 0.03) overall average daily gain compared to those grazing CHIC (35 g/d ± 5 g/d); BFT (53.2 g/d ± 5 g/d) was intermediate. When averaged over the season, there was a weak trend (P = 0.19) for goat kids grazing CHIC (2,034 epg) to have greater FEC compared to RCL (1,194 epg); BFT (1,718 epg) was intermediate. Typically goat kids grazing CHIC had greater (P < 0.001) monthly FAMACHA© scores than those grazing RCL with scores for goats grazing BFT similar to RCL. There was a weak trend for number of dewormer doses administered based on FAMACHA© scores to be less (P = 0.13) when goats grazed RCL (5.5 doses) compared to CHIC (6.3 doses); BFT (6.1 doses) was intermediate. Grazing red clover pasture, and to some extent birdsfoot trefoil, appeared to have a beneficial effect on meat-goat kid performance and on GIN-parasite infection (low FEC) in comparison to chicory pastures.

A reduction in enteric CH4 production in ruminants is associated with improved production efficiency. Enteric CH4 and CO2 production associated with the livestock industry is of interest due to the impact these emissions might have on global climate change. Our objective was to evaluate the effect of cow frame size (FS) and season on enteric CH4 and CO2 production in cattle grazing during summer and fall. Twenty-eight Angus cows (545 ± 49 kg BW) of either medium (n = 14) or large FS (n = 14) and grazing simultaneously within a native tallgrass prairie pasture in central Oklahoma were used to estimate individual animal enteric CH4 and CO2 production daily (via a commercially available breath analyzer) over the summer and fall seasons. Cow FS was categorized based on frame scores generated from individual hip heights. Summer and fall season designations were based on summer and winter solstices and the fall equinox. Statistical analyses were conducted using GLM of SAS. The model included class effects of FS and season and their interaction. As measured at the beginning of the experiment, large-FS cows were heavier (P < 0.001) and had a greater frame score (P < 0.001) compared with medium-FS cows (609 vs. 480 kg and 6.8 vs. 4.6, respectively). As measured during the experimental period, large-FS cows produced calves with heavier (P < 0.01) 205-d adjusted weaning weights (261 vs. 222 kg). There were no frame size × grazing season interactions with regard to enteric gas production. Large-FS cows produced greater (P < 0.001) enteric CH4 (280 vs. 248 g/d) and CO2 (9,065 vs. 8,021 g/d) than medium-FS cows. Cows produced higher (P < 0.001) amounts of enteric CH4 and CO2 in summer than in fall (292 vs. 236 g/d and 9,065 vs. 8,021 g/d, respectively). When expressed as total production (over the entire summer and fall seasons) of CH4 or CO2 per weight unit of weaned calf, enteric gas production did not differ between large- and medium-FS cows (0.20 vs. 0.21 kg/kg and 6.4 vs. 6.6 kg/kg, respectively). Further research is needed to relate enteric gas production to herbage nutritive value and animal DMI.

This study evaluated performance and health parameters associated with gastrointestinal parasite control when lambs and meat-goat kids were finished on a mixed sward of orchardgrass (Dactylis glomerata L.), red clover (Trifolium pratense L.), and white clover (Trifolium repens L.) with and without supplemental whole cottonseed (Gossypium hirsutum; WCS). Overall average daily gain (ADG) for this 90-d period was increased by supplementation with WCS in Suffolk lambs (P < 0.003), Katahdin lambs (P < 0.17) and goat kids (P < 0.10). Fecal egg count (FEC) was variable over the grazing season each year, but was not impacted by supplementation of WCS at 0.5 percent body weight (BW). Katahdin lambs had lower FEC than Suffolk lambs and typically goat kids. Goat kids and Suffolk lambs had lower (P < 0.001) blood albumin and higher (P < 0.001) globulin concentrations than Katahdin lambs. Supplementation with WCS did not improve FAMACHA© scores, but Katahdin lambs consistently had lower (P < 0.001) FAMACHA© scores than Suffolk lambs and goat kids. Goat kids had the highest FAMACHA© scores. Using FAMACHA© as a means to identify Haemonchus contortus-induced anemia resulted in a mean 56-percent reduction in doses of dewormer administered compared to a theoretical monthly dosing of each animal. After the initial administration of dewormer, days to next dosing of dewormer were fewest for goat kids (33 d), followed by Suffolk lambs (67 d), and greatest for Katahdin lambs (77 d). By considering the use of breed groups resistant to or having high resilience to internal parasites and coupling with the use of the FAMACHA© system to determine the need to deworm individual animals, producers can improve livestock performance and reduce overall cost of production.

ABSTRACTCanopy reflectance (i.e., remotely sensed) data may allow rapid assessment of nutritive values, such as total N, neutral detergent fiber (NDF), and acid detergent fiber (ADF), as well as nutritive quality indicators such as relative feed value (RFV) and a forage energy/protein ratio of alfalfa (Medicago sativa L.). Remotely sensed data were acquired over seven alfalfa cultivars in the 2005 to 2008 growing seasons (n = 580) to develop and test calibration equations to predict concentrations of total N, NDF, and ADF. About 31% of the canopy reflectance dataset and corresponding measured values of total N, NDF, and ADF were used in calibration equation development while the remaining samples (69%) were used to validate the calibration equations. The remote sensing based values of NDF, ADF, and crude protein (CP = total N × 6.25) were used to calculate RFV and the total digestible nutrients/crude protein (TDN/CP) ratio. Measured total N, NDF, ADF, RFV, and the TDN/CP ratio were used to assess the accuracy of the corresponding predicted values from the remotely sensed canopy reflectance data. The remotely sensed based prediction equations explained from 78 to 83% of the variation in measured total N, NDF, and ADF, correctly predicted about 80% of the RFV‐based hay grade classifications, and about 78% of the measured TDN/CP ratios. This technology could help improve profit margins by timing the cutting or harvesting of alfalfa, in rapid assessment of nutritive values over large areas devoted to growing alfalfa, and assessing nutritive quality in real time.