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© 2007 Plant Management Network.
Accepted for publication 6 June 2007. Published 26 September 2007.

Quality of Stockpiled Pasture and Hay Forages

Andrew P. Robinson, Department of Agronomy, Purdue University, West Lafayette, IN 47907 (formerly, Brigham Young University, Plant and Animal Sciences Department, Provo, UT 84602); R. D. Horrocks, Brigham Young University, Plant and Animal Sciences Department, Provo, UT 84602; David D. Parker, Intermountain Farmers Association, 240 West First North, Price, UT 84501 (formerly, Brigham Young University, Plant and Animal Sciences Department, Provo, UT 84602); and Darrin F. Robert, Department of Agronomy, University of Nebraska, Lincoln 68583 (formerly, Brigham Young University, Plant and Animal Sciences Department, Provo, UT 84602)

Corresponding author: R. D. Horrocks. dwain@horrocks.net

Robinson, A. P., Horrocks, R. D., Parker, D. D., and Robert, D. F. 2007. Quality of stockpiled pasture and hay forages. Online. Forage and Grazinglands doi:10.1094/FG-2007-0926-01-RS.

Abstract

Stockpiling characteristics of tall fescue and orchardgrass have been widely reported, but potential of other forages in the Intermountain West is less well known. Therefore, research was conducted 2002 through 2004 to evaluate nutritive value and DM yield of thirteen grasses and legumes. Stockpiled DM yield at the beginning of the deferred-grazing period (1 October) was recorded and forages were sampled at intervals of 9 to 22 days during the deferred-grazing period and crude protein (CP) and relative feed value (RFV) were determined. During the deferred-grazing period DM yield was measured in 2003 and 2004. Best suited for stockpiling, based on average available DM yield on 1 October and ability to maintain forage quality, were tall fescue (3.96 Mg/ha), orchardgrass (3.64 Mg/ha), and meadow bromegrass (3.60 Mg/ha). Meadow foxtail was also suitable for stockpiling, although it accumulated less dry matter (2.72 Mg/ha). Smooth bromegrass was not suited for stockpiling because stockpiled DM yield (2.78 Mg/ha) declined rapidly with the onset of inclement weather. Reed canarygrass required a double application of N (348 kg/ha) to prevent extreme chlorosis and thus was economically unsuited for stockpiling. Among the legumes evaluated only birdsfoot trefoil (3.11 Mg/ha) was suitable as stockpiled forage.

Stockpiling Forage for Late Season Grazing

Research has shown stockpiling forage to be economically beneficial to the producer (18,20) while maintaining adequate yield (8,15) and nutrition levels for various classes of livestock (3,6,17). The cost of producing and storing forage for the winter months is often the largest expense incurred and is usually the most labor-intensive practice used by graziers. Stockpiling forage can lengthen the grazing season and reduce the labor needed to winter beef cows by as much as 25% (18). Grazing stockpiled forages during late autumn and early winter has been shown to reduce costs by approximately $47 per cow (20). Some forage loss may occur with stockpile mismanagement, but if governed properly loss can be kept to a minimum.

Application of N in late summer (approximately 1 August) to grasses intended for stockpiling will decrease dead material (5,17), increase stockpiled dry matter (DM) yield (5,15,21), provide economic benefits by saving money otherwise spent on winter feed hay (15), reduce concentrations of neutral detergent fiber (NDF) (5), and increase concentrations of crude protein (CP) (5,21). However, increases in the cost of N fertilizers may result in less advantageous economics for this system.

The quality of stockpiled forages is determined by multiple factors, including plant species, climate, accumulation period, and fertilization timing and rate. Appropriate species selection can allow producers to claim the highest level of nutrients available and thus maximize livestock production. Among the species used for stockpiled forage, tall fescue has been found to be an excellent forage because of its ability to maintain yield and quality better than many other grasses throughout late autumn and early winter (2,3,13). In the spring following stockpiling, fescue continues to yield well (13). Less is known about the quality of other stockpiled grasses and legumes (8).

The objective of this study was to evaluate the nutritive quality and DM yield of 13 different stockpiled forages during the period from approximately 1 October to early December under arid-irrigated conditions of the Intermountain West.

Evaluating Nutritive Value and DM Yield of Grasses & Legumes

The experiment was conducted over a three-year period, 2002 through 2004, on a calcic argixerolls, fine loamy, mixed mesic soil (Timpanogos silty clay loam) at the Brigham Young University Agriculture Station near Spanish Fork, UT (40°08’N, 111°40’W, elevation 1387 m). Soil samples were obtained from the site prior to initiation of the experiment. Analyses showed there was adequate P (30 ppm) (14) and potassium (230 ppm) (16) and a slightly alkaline pH of 7.3.

The previous crop was corn (Zea mays L.). Before planting, the soil was plowed, disked, harrowed, and compacted with a roller. Plot size was 2 × 7 m. Thirteen common pasture forage crops were seeded on 2 May 2001. They were common alsike clover (Trifolium hybridum L.), common Ladino whiteclover (T. repens L.), ‘Champ’ and ‘Nitro Plus’ alfalfa (Medicago sativa L.), common birdsfoot trefoil (Lotus corniculatus L.), ‘Barmultra’ Italian ryegrass (Lolium multiflorum Lam.), ‘Manchar’ smooth bromegrass (Bromis inermis Leyss.), ‘Regar’ meadow bromegrass (B. riparius Rehm.), ‘Fuego’ and ‘Fawn’ tall fescue (Festuca arundinacea Schreb.), ‘Ambassador’ orchardgrass (Dactylis glomerata L.), ‘Palaton’ reed canarygrass (Phalaris arundinacea L.), and ‘Garrison’ meadow foxtail (Alopecurus pratensis L.).

Due to a severe weed problem, primarily green foxtail (Setaria viridis L. Beauv.), plots were mowed several times during the 2001 establishment year to control the weeds. Data were not collected until the 2002 growing season. Weed competition had such a deleterious affect on meadow foxtail and reed canarygrass that no data were collected in 2002 on these two species.

Grasses received N at the rate of 87 kg/ha (as ammonium sulfate) at the time of planting and after the first and last harvest each year of the study (2002-2004). Reed canarygrass, even at this rate, was extremely chlorotic in 2002, so the applied N was doubled for this cultivar in 2003 and 2004. Plots were irrigated as needed (Table 1). Forages were harvested during each growing season according to a typical haying schedule; this included an initial harvest at first bloom for legumes and at anthesis for grasses. Thereafter, two to three secondary harvests, depending on the species, were made after 30 to 40 days of regrowth.

Table 1. Average supplemental irrigation (mm) applied during
the summer months during the three years of this study.

 * Since there was little variation in applied irrigation water
among years, the average is presented.

The stockpile accumulation period began approximately 1 August and continued until about 1 October, at which time part of each plot was harvested to determine DM yield and provide material for quality evaluations. Thereafter, the plots were sampled at intervals of 9 to 22 days, depending on the weather, until snow prevented further sampling (Table 2). In 2002, samples for analysis of nutritive value were hand clipped from a 0.3 × 0.3 m area. In 2003, because of favorable weather conditions plots (1.1 × 2.0 m) were harvested with a mechanical forage harvester for the first three harvests. Because of inclement conditions which prevented mechanical harvesting, the last two harvests were removed with hand clippers from plots measuring 0.3 × 0.3 m. In 2004, plots were harvested using the mechanical harvester for the first and last harvests and hand clipping for the middle two harvests. Areas sampled were the same as in 2003. These sampling regimes were dictated by weather conditions. Samples were dried for 10 days in a forced air dryer at 55 to 60°C, then ground through a Wiley mill (Arthur H. Thomas, Philadelphia, PA) equipped with a 1-mm screen. Samples were then reground through a Cyclotec 1093 mill (Foss North America, Eden Prairie, MN), also equipped with a 1-mm screen.

Table 2. Sampling dates during the deferred-grazing periods.

Concentrations of N within each sample were determined (11) utilizing a LECO FP-2000 (LECO Corp., St. Joseph, MI) combustion analyzer. Chemical analyses for ADF and NDF were completed using the Ankom 200 Fiber Analyzer (1). Relative feed values were calculated as follows (7):

RFV = (%DDM × %DMI) / 1.29, where

%DDM = 88.9 – (%ADF) (0.779) and

%DMI = 120 / %NDF.

Analysis of variance (General Linear Model procedure) and mean separations (Tukey’s Studentized Range) were accomplished using SAS (SAS Institute Inc., Cary, NC) procedures. The experiment was a split-split plot randomized-complete-block design (RCBD) with years being the first split and harvest dates the second. Initial analyses, RCBD in time (years as main plot) within harvest dates showed the interaction of species and years was significant (P ≤ 0.05). Data were subsequently analyzed and reported as a RCBD within each harvest/sampling date (within years). The error term for each date within years was the species × harvest date interaction. Reasons for handling analyses in this manner were twofold: (i) the significant interaction of species and years; and (ii) our primary interest was comparison of differences in CP, RFV, and DM yield within harvest dates. Tukey’s Studentized Test was used for separating means due to its conservative nature.

Monthly precipitation and average temperature for 2002, 2003, and 2004 are reported in Table 3. The weather station was approximately 3 km from the experimental site.

Table 3. Monthly precipitation and average monthly air temperature during deferred-grazing periods in 2002, 2003, and 2004 at the Spanish Fork Power House Weather Station (3 km from experimental site).

Species Deleted from the Experiment

Of the thirteen species planted in 2001, common alsike clover and Italian ryegrass did not maintain stands after the first harvest year (2002). Common Ladino clover deteriorated so rapidly when subjected to inclement weather conditions that no harvestable DM was left after the first killing frost. Reed canarygrass required twice the N of the other grasses to eliminate extreme chlorosis of the leaf blades (348 kg of N per ha). Therefore, these four forages were deleted from all summaries of results. Also, the two alfalfa species and the two tall fescue species were statistically equal in every measure, thus results were averaged and presented as alfalfa and tall fescue, respectively.

Available Stockpiled Dry Matter

For a forage crop to be a successful candidate for stockpiling, it is important to know whether it is capable of maintaining biomass that is accessible and acceptable to grazing animals during the late autumn and early winter. Sampling DM yield during the deferred-grazing period was highly subject to variability of the weather, particularly precipitation (Table 3).

Dry matter yield at the beginning of the deferred-grazing period, which had accumulated during the period 1 August through 30 September, varied each year (Table 4). In 2002, stockpiled dry matter at the beginning of this period ranged from 2.69 Mg/ha for smooth bromegrass to 4.74 Mg/ha for tall fescue. Tall fescue, alfalfa, and birdsfoot trefoil had statistically equal amounts (P ≤ 0.05) of dry matter available the first week in October (Table 4). In 2003, stockpiled dry matter for the forages at the beginning of the fall-winter grazing period ranged from 1.44 to 3.52 Mg/ha for alfalfa and orchardgrass, respectively. Meadow bromegrass, tall fescue, and orchardgrass had statistically equal amounts (P ≤ 0.05) of dry matter available (2.98 to 3.52 Mg/ha) at the beginning of the deferred-grazing period. In the final year of the study, 2004, stockpiled dry matter ranged from 3.12 Mg/ha for meadow foxtail to 4.63 Mg/ha for orchardgrass. In 2004, dry matter yield of meadow bromegrass, tall fescue, and orchardgrass were statistically equal (P ≤ 0.05)

Table 4. Dry matter available at the beginning of the deferred-grazing period
in 2002, 2003, and 2004 and the average over the three-year period (Mg/ha).

 * Values within a column followed by the same letter do not differ significantly (P ≤ 0.05, Student-Newman-Kuhls, SNK, Multiple Range Test). The year × cultivar interaction was significant (P ≤ 0.05), thus above data were analyzed within years as a RCBD.

Decline in Dry Matter During the Grazing Period

In 2002, DM yield at each sampling date after 4 October was not recorded. However, it was observed that after being subjected to snow, freezing, and thawing, the amount of harvestable forage declined precipitously for some species and less for others. The same general pattern was apparent in 2003 and 2004.

During 2003, the grasses and birdsfoot trefoil either maintained or increased DM yield between 30 September and 14 October (Fig. 1), whereas alfalfa declined (P ≤ 0.05). All species showed significant decreases in DM yield after 14 October as inclement weather became more prevalent. Tall fescue, meadow bromegrass, and orchardgrass accumulated more (P ≤ 0.05) by 30 September and 14 October than the other forages, but by 15 November all species had the same amount of dry matter available, approximately 0.4 Mg/ha.

Fig. 1. Stockpiled dry matter during the late-autumn/early-winter grazing period in 2003. (*HSD within each harvest date is the minimum significant difference, Tukey’s Studentized Range, P ≤ 0.05).

Available dry matter during the stockpile period in 2004 was recorded for the first and last harvests (Fig. 2). Due to inclement weather at the two intermediate sampling dates DM yields were not taken. Meadow bromegrass and orchardgrass had significantly more stockpiled dry matter than the other forages at the beginning of the deferred-grazing period (5 October). By 17 November it was evident that birdsfoot trefoil, tall fescue, and orchardgrass weathered better than the other species.

Fig. 2. Stockpiled dry matter during the late-autumn grazing period in 2004. Bars capped by the same letters within dates do not differ significantly (Tukey’s Studentized Range, P ≤ 0.05).

Quality of Stockpiled Forage

Crude protein (CP). Crude protein concentration at the beginning of the deferred-grazing period was highest in alfalfa (Fig. 3). In 2003, with the exception of the third date, CP concentrations of the legumes were significantly higher (P ≤ 0.05) than those measured in the grasses. Generally, crude protein concentrations declined throughout the late-autumn/early-winter grazing period each year for all species. Because of temperature and precipitation patterns favoring growth, the decline in CP was delayed until after 20 October in 2004, whereas the decline began after the first sampling date (approximately 1 October) both 2002 and 2003.

Fig. 3. Crude protein (CP) of stockpiled forages during the late-autumn/early-winter deferred-grazing period. No data were collected for meadow foxtail in 2002. (*HSD within each harvest date is the minimum significant difference, Tukey’s Studentized Range, P ≤ 0.05).

Relative feed value (RFV). During 2002, RFVs of stockpiled legumes were significantly greater (P ≤ 0.05) than grasses during the first two sampling periods (4 and 24 October), but there were few discernable difference among the species thereafter (Fig. 4a). Relative feed values for legumes tended to decline throughout the fall and early winter period each year, but changes in grasses was less dramatic. During the stockpile period of 2002, grasses exhibited the following changes: smooth bromegrass declined 0.74 units/day; orchardgrass declined 0.50 units per day; and meadow bromegrass declined by 0.29 units per day (Fig. 4a). Relative feed values for tall fescue and birdsfoot trefoil increased, 1.15 and 3.05 units/day respectively, during the period 15 November through 5 December due to favorable weather conditions.

Fig. 4. Relative feed value (RFV) of stockpiled forages during the late-autumn/early-winter deferred-grazing period. No data were collected for meadow foxtail in 2002. (*HSD within each harvest date is the minimum significant difference, Tukey’s Studentized Range, P ≤ 0.05).

Legumes maintained significantly higher RFVs than the grasses throughout the 2003 stockpile period (Fig. 4b). The decline for the legumes over the period 30 September through 3 December averaged 0.98 RFV units/day. Meadow bromegrass, smooth bromegrass, and meadow foxtail declined an average of 0.48 units/day during the same period. Tall fescue declined only 0.25 unit/day.

Again in 2004, legumes maintained significantly higher RFVs than the grasses at all sampling dates during the stockpile period (Fig. 4c). On the last sampling date RFV of alfalfa did not differ (P ≤ 0.05) from the grasses. After the second sampling date, RFV for legumes declined at an average rate of 5.9 units per day for the remainder of the season. Meadow bromegrass, smooth bromegrass, and meadow foxtail declined an average of 1.4 units/day throughout the period from 5 October through 16 November. Orchardgrass and tall fescue declined an average of 0.55 RFV units/day during the same period.

Discussion and Summary of Results

The highest yielding grasses throughout the study were tall fescue and orchardgrass. These grasses maintained a high level of available dry matter throughout the deferred-grazing period by minimizing forage deterioration due to inclement weather, thus making them suitable grasses for deferred grazing. Our findings for these two grasses are similar to those reported by others (13,15,16,17). During 2002, tall fescue exhibited a significant increase (P ≤ 0.05) of 45% in DM yield during the first two weeks of October, which supports the idea that it is capable of growth at lower temperatures (13,17). It was also found that meadow bromegrass was quite well suited for use in deferred-grazing systems because it generally had DM yield, CP, and RFVs similar to tall fescue and orchardgrass, though in 2004 deterioration of dry matter by meadow bromegrass was more rapid. Meadow foxtail was intermediate in its suitability for stockpiling, but it was superior to smooth bromegrass. Based on the results of this study, smooth bromegrass would not be considered suitable for stockpiling.

Among the legumes evaluated, birdsfoot trefoil was best suited for stockpiling. Birdsfoot trefoil is a legume that will not cause bloat and it will persist better than many other forages under continuous grazing (7,10). None of the other legumes, including alfalfa, alsike clover, Ladino clover, and red clover, were found to be suitable for stockpiling at this site. Alfalfa should continue to be grazed in a manner consistent with norms in temperate, irrigated regions; aftermath should be grazed soon after the first killing frost to prevent loss of dry matter and quality. This is not detrimental to stand longevity as long as trampling under wet conditions is avoided (9).

Assuming no grazing loss, the average amount of stockpiled forage accumulated between 1 August and 1 October could provide between 7 and 21 days of deferred grazing for a 454-kg cow consuming 12 kg dry matter per day (Table 5). In addition to the amount of forage available, however, other factors determining the number of grazing days are the degree to which inclement weather causes dry matter loss and the accumulation of snow. To utilize the maximum amount of dry matter, alfalfa should be grazed within a 7-day period following the first killing frost. In this study this means that 32 animals per hectare would be required to consume the available forage. Smooth bromegrass, which has a grazing window of about 14 days after 1 October would support 17 animals per hectare for that 14-day period. After the middle of October smooth bromegrass deteriorates rapidly losing much of its harvestable dry matter. The other species should be expected to provide a 21-day grazing period before inclement weather caused excessive dry matter loss. Thus the carrying capacity during this period would range from 11 animals per ha for meadow foxtail to 15 for tall fescue (Table 5).

Table 5. Potential of various forages for stockpiled grazing.

 ^× Animal unit days; 454-kg cow consuming 12 kg dm/day.

 ^y To reduce field losses due to inclement weather. This column is based on best management for each species, but does not account for normal grazing loss.

 ^z Number of animals required per hectare to remove dry matter in allotted time.

Crude protein for each forage was at least 7% on 15 November. At the rate of DM removal presented in Table 5, protein would be more than adequate during the suggested grazing period. A 454-kg pregnant cow during the last trimester requires approximately 0.73 kg protein per day (12). Dry matter utilization suggested here would supply a minimum of 1.2 to 1.5 kg protein per day depending on the forage grazed. Since it is not realistic to assume 100% utilization, nor 100% digestibility of CP, stocking rate must be adjusted accordingly. Research indicates that wastage can be as high as 34% in rotational grazing (19). Approximately 72% of CP is digestible by ruminants (12).

Relative feed value of all forages was maintained above 100, a value equivalent to full-bloom alfalfa, throughout the late-autumn/early-winter grazing period, thus indicating that quality of the forage grasses was sufficient to ensure relatively high intake. The legumes had extremely high RFVs during the first half of the late-autumn/early-winter grazing periods.

Economics play an important role in stockpiling forages. With increasing prices for nitrogen fertilizer, producers must be aware of and use good economic principles in purchasing and applying fertilizers to their pastures (4,15). Presently, the cost of N, which is essential for grass production in low organic irrigated soils found in western states, renders stockpiling less favorable than it once was. However, it still may be preferable to buying or producing hay. An alternative may be to provide N by including a suitable companion legume crop when seeding pasture grasses. This study suggests that birdsfoot trefoil may hold the highest potential for this purpose. The information provided by MacAdam et al. (10) support this premise. Further studies are required to evaluate and quantify the birdsfoot trefoil-grass relationship in stockpiled forages used in deferred-grazing systems.

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