Bluestem Hay Research Articles

Switchgrass and Big Bluestem Hay, Biomass, and Seed Yield Response to Fire and Glyphosate Treatment

Timing of spring fire and glyphosate [N‐(phosphonomethyl)glycine] treatments is critical to control weeds without compromising production of warm‐season grasses. To determine the forage and seed yield response we burned or applied glyphosate to switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) in mid‐April, early May, and late May in 1998 and 1999 at Rock Springs, PA. Compared with fire in mid‐April or early May, a late May burn in 1998 reduced July dry matter yields (simulating a hay harvest) by 40 to 48% but did not affect dry matter yields in September (simulating a biomass feedstock harvest) of either grass. In switchgrass, glyphosate applied in late May reduced July yields by 70% and September yields by 30%. In bluestem, late May application of glyphosate reduced July yields by 90% and September yields by 40%. In both grasses, fire in late May reduced yields less than a late May application of glyphosate. Late May glyphosate treatments reduced seed yield compared with the mid‐April date. We conclude that in central Pennsylvania switchgrass or bluestem can be burned through the first week of May (10–15 cm growth) with little effect on hay or biomass yield. Glyphosate should be applied (i) before mid‐ to late April (just before green‐up) if switchgrass or big bluestem is to be harvested as hay in July or for seed in September, or (ii) by the first week of May if the cumulative growth is to be harvested once in autumn.

Plant and Soil Responses to Source, Rate, and Timing of Applied N for Plains Bluestem Production

In western Oklahoma, one of the most popular grass species being used for pastureland is Plains bluestem (Bothriochloa ischaemum L.). Despite the current importance of this species, N fertilizer sources, rates, and timing of application have not been thoroughly evaluated for this species. The objective of this 3-yr study was to evaluate the effect of source, rate, and timing of applied N on Plains bluestem forage production. Two established stands of Plains bluestem in Stillwater and Bessie, OK, were selected as experimental sites. A randomized complete block design with three replications was employed at each location. Urea and ammonium nitrate were evaluated at rates of 50, 100, 200, and 400 lb N/acre. Time of fertilizer application was evaluated using late April and early May applications. Dry matter yield, crude protein (CP), and N uptake increased with applied N up to 200 lb N/acre for both sources. The maximum average (3-yr) yields were 4112 and 3370 lb dry matter/acre at Stillwater and Bessie, respectively. No effect on production was found to exist due to N source. Applying 50 and 100 lb N/acre in early May increased yields at Stillwater 25 and 14%, respectively, compared with the same rates applied in late April. This study indicated that Plains bluestem forage yield, N uptake, and CP content increased significantly when up to 200 lb Nlacre was applied in the spring. Dry matter production was further increased when N was applied in early May compared with late April.

Assessing nutrient composition and digestibility of tallgrass-prairie hay (1996)

Thirteen steers were used in a 4 13 incomplete Latin square to determine chemical composition and digestibility for 13 samples of tallgrass prairie hay. Hays were collected from a variety of locations in east-central Kansas and represented a wide array of harvest dates and storage conditions. Steers were fed prairie hay and soybean meal at 1.5% and .2% of body weight, respectively, to equalize intakes relative to body weight and prevent degradable intake protein (DIP) from limiting extent of digestion. Prairie hay samples were analyze d for N, ADIN, ADF, NDF, ADIA, monosaccharides (sugars), and alkali-labile phenolic acids (lignin components). The relationships of various forage chemical components to diet organic matter digestibility (OMD) were examined using simple, linear regression. There was a close relationship between OMD and ADF (r 2 = .62; OMD = .822 [ADF] + 96.47). In addition, the ratio of xylose:glucose (r2 = .62; OMD = 41.93[X:G] + 94.14) explained significant amounts of the variation in OMD. Defining the chemical composition of bluestem hay may be of value in predicting organic matter digestibility and, ultimately, energetic value.

Application of 13CO2 measurements to the estimation of energy expenditure in goats

The use and limitations of 13C stable isotopes as tracers in animal experimentation was investigated using 13C-labeled bicarbonate to estimate CO2 production and energetic requirement of free-ranging goats. Goats were fed wheat hay (Triticum aestivum; C3) or Old World Bluestem hay (Bothriochloa caucasica; C4; OWBS) ad libitum for 21 d. Parotid salivary ducts were cannulated for saliva collection. Isotopic bicarbonate (13C) was infused at a constant rate into the peritoneal cavity. In exp. 1, saliva samples were obtained at successive 2-h periods for 20 h to establish the time to achieve equilibrium. The half-life of bicarbonate was 2.9 h for animals consuming the wheat diet and 4.1 h (P < 0.06) for animals consuming OWBS diet. The time required to reach equilibrium was 12 h for animals on the wheat diet and 16 h for animals on OWBS diet. The error in the technique arising from animals consuming C3 vs. C4 species (which have different endogenous 13C contents) was studied in exp. 2. If species composition (C3 vs. C4) of the diet remains constant within 10%, the error is negligible. In exp. 3, estimation of CO2 production from continuous saliva samples had a lower coefficient of variation (6.3 vs. 10.0%) than measurements based on spot serum samples. Energy expenditure of goats in stalls consuming hay ad libitum was similar to that of ad-libitum-fed sheep at similar body weights. The 13C methodology appears to be a promising method for measuring energy expenditure of grazing animals. Key words: Energy requirement, stable isotopes, carbon dioxide, sodium bicarbonate

Estimating Salivary Flow and Ruminal Water Balance of Intake, Diet, Feeding Pattern, and Slaframine

Three experiments with ruminally fistulated cattle fed 12 times daily were conducted to study the role of saliva secretion in ruminal water balance when intake, diet, and feeding pattern were altered. Water balance data were determined from continuously infused Co-EDTA and pulse-dosed Cr-EDTA with saliva flow estimated by difference between water intake and ruminal outflow. Any net transruminal water flux would be included in the estimate of salivary flow. When the concentration of bluestem hay in the diet was increased from 50 to 90%, ruminal fluid volume, saliva secretion, water intake, dilution rate, and total ruminal outflow increased. At equal intake, the higher forage diet increased ruminal liquid volume, outflow, and saliva secretion but had no effect on dilution rate. Intake, but not forage concentration, affected ruminal pH when 50 and 90% hay diets were fed. Increasing feeding frequency of forage in a 65% bluestem hay diet from 4 to 12 times daily (the grain portion was fed 12 times daily) increased dilution and ruminal outflow; however, the latter was only significant with data from Cr-EDTA. Ruminal volatile fatty acids were not altered by feeding frequency of forage. Nycterohemeral patterns were seen in water intake, ruminal dilution rate, outflow, and salivary flow in both studies. Slaframine increased saliva flow by 29% and was accompanied by increased ruminal liquid volume, dilution rate, and outflow.

Evaluation of mixed lucerne and caucasian bluestem hay diets fed to sheep

Several in vitro experiments, a digestion trial and a growth trial were performed to determine dry matter (DM) and fiber digestibilities, rate and extent of in vitro DM disappearance, ammonia-nitrogen (NH3-N) release, N metabolism variables, intake and average daily gain in sheep fed various combinations of lucerne and caucasian bluestem hay. Dietary treatments were prepared with lucerne replacing bluestem at 0, 25, 50, 75 and 100% of dietary DM. Associative effects between forages were evaluated. In vitro NH3-N accumulation exhibited a cubic response (P < 0.01) to percentage of lucerne at 6 h of incubation. A positive associative effect on NH3-N accumulation was evident at 6 h, with the 25% lucerne substrate having greater NH3-N accumulation compared with the 0 and 100% lucerne substrates. The extent of DM, acid detergent fiber (ADF) and cellulose disappearance, and the rate of DM and neutral detergent fiber (NDF) disappearance, decreased (P < 0.05) linearly as the percentage of lucerne increased. However, the addition of lucerne resulted in a linear increase (P < 0.01) in the rate of in vitro DM digestion early in fermentation (0–24 h).In the digestion trial, DM, NDF, ADF and cellulose digestibilities decreased linearly (P < 0.001) as dietary lucerne level was increased. Nitrogen intake, apparent N digestibility and N balance were found to increase linearly (P < 0.001) with increasing lucerne percentage. Quadratic responses (P < 0.05), indicating that positive associative effects occurred between lucerne and caucasian bluestem, were found for hemicellulose digestibility, apparent N digestibility and percent N retained. Metabolic fecal N was determined to be 5.78 g N kg−1 DM intake and no effect (P > 0.90) was observed on true N digestibility due to increasing lucerne in the diet. Diets varying in lucerne were fed ad libitum to 2 pens of lambs (6 lambs per pen; average initial weight, 20 kg) in a 56-day growth trial. Dry-matter intake increased linearly (P < 0.05) as the percentage of lucerne in the diet increased. Quadratic (P < 0.05) responses to an increasing percentage of lucerne were observed for average daily gain (ADG) and feed to gain ratio.Addition of lucerne to caucasian bluestem hay increased the amount of N and cell solubles available for microbial growth and fiber digestion, resulting in increased intake and animal performance despite decreased digestibility.

Nitrogen utilization, ruminal fermentation and abomasal nitrogen flow in sheep fed caucasian bluestem hay supplemented with lucerne or urea

Four crossbred wether lambs with ruminal and abomasal cannulae were used in a Latin square design to measure nitrogen (N) utilization, ruminal fermentation parameters and abomasal N flows for diets of caucasian bluestem hay alone (BLUESTEM) and supplemented with 50% lucerne (BLUE + LCRN), 9.6 g urea once daily (DOSED UREA) or 9.6 g day−1 urea continuously infused (INFUSED UREA). Lambs consuming BLUE + LCRN had lower (P < 0.05) intakes of neutral detergent fiber (NDF), hemicellulose and cellulose, and lower (P < 0.05) digestibility of acid detergent fiber (ADF) compared with those fed BLUESTEM, DOSED UREA or INFUSED UREA. Supplementation increased (P < 0.05) N intake and apparent digestibility regardless of the source. At 4 h post-feeding, ruminal ammonia (NH3-N) was increased (P < 0.05) by N supplementation over the BLUESTEM diet. The BLUE + LCRN diet resulted in lower (P < 0.05) ruminal pH from 2 to 8 h post-feeding compared with BLUESTEM, DOSED UREA or INFUSED UREA. Total concentration of ruminal volatile fatty acids (VFA) at 2 h post-feeding was greater (P < 0.05) for BLUE + LCRN compared with BLUESTEM, DOSED UREA or INFUSED UREA. Proportions of acetate, butyrate, iso-butyrate and iso-valerate were unaffected (P > 0.10) by supplementation. Propionate was increased (P < 0.05) on the BLUE + LCRN diet. No differences (P > 0.10) in abomasal flow of particulate dry matter (DM), non-NH3-N (NAN) and microbial N were evident. More (P < 0.05) NH3-N reached the abomasum in lambs receiving supplemental N. Ruminal escape of feed N was greater (P < 0.05) for the BLUESTEM diet compared with BLUE + LCRN and INFUSED UREA. Microbial N, as a percentage of total abomasal N, did not differ (P > 0.05) between diets. Results of this study indicate that low levels of ruminal NH3-N found on the BLUESTEM diet were not limiting microbial protein synthesis. Supplementation with lucerne appeared to stimulate the rate of early ruminal fermentation as evidenced by lower ruminal pH and greater concentration of total ruminal VFA 2 h post-feeding. This may help to explain the improved performance observed with the addition of a legume to a warm-season grass diet.

Increased Utilization of Bluestem Hay with the Addition of Water or Certain Protein Sources

A two phase experiment was conducted with 28 lambs to test ways of increasing the intake and nutritive value of a low protein mixed grass forage (Primarily Andropogon spp). During phase one lambs were fed hay ad libitum for 30 days. Treatments were control and two levels of water sprayed over the hay prior to each feeding. Added water resulted in a significant increase in digestibility of fibrous components and in digestible and metabolizable energy per gram of dry matter (DM). Voluntary water intake decreased with increasing amounts of water sprayed over the hay. In phase two, four different milo-based protein supplements were fed with the hay Rations containing dehydrated alfalfa meal and corn gluten meal had increased digestibility coefficients and total digestible nutrients (TDN) compared with rations containing soybean meal or brewer's dried grains. No differences in intake parameters were noted among the four treatments. Average daily gain (ADG) and average daily potassium gain were significantly affected by the source of supplemental protein. Carcass grades and specific gravity of lambs supplemented with brewer's dried grains or dehydrated alfalfa were higher than in the other two groups. The data indicate that rations containing 60% grass hay can, when properly supplemented, support excellent performance in lambs.