Source: Ontario Ministry of Agriculture, Food and Rural Affairs
FactSheet written by: Jim Johnston – Forage and Sheep Researcher/New Liskeard Agricultural Research Station, University of Guelph; Christoph Wand – Beef Cattle, Sheep and Goat Nutritionist/OMAFRA
Stockpiling is the practice of saving certain hay or pasture fields for grazing in the fall, and winter, after forage growth has stopped. Stockpiled pasture is also referred to as fall-saved pasture or deferred grazing, and is one of several extended grazing techniques.
The primary reason for using stockpiled forage is to reduce feed and feeding costs. For each week that the grazing season is extended, total annual feed costs for a forage-fed animal (i.e., ewes or beef cows) are reduced by about 1%. This saving reflects the harvesting costs for grazed forage as compared to hay or silage harvesting, primarily on account of machinery, labour and other inputs not experienced in harvesting the same forage by grazing. Also livestock, grazing stockpiled pasture, spread their manure back onto the pasture without the cost of conventional manure hauling and spreading.
The most important management factor in determining how much forage will be available for fall grazing is the “summer resting date”. This is the date in the summer when the animals are removed from the pasture so that it can re-grow and be stockpiled for use in the fall and winter. In the case of a hay field, it is the date when the most recent forage (hay or silage) crop is removed. The earlier in the season that the pasture is rested, the greater the fall pasture yield will be (Figure 1). At New Liskeard, pasture that was stockpiled after mid-July had a fall (October/November) yield of 4500 kg/ha (4050 lb/acre) while similar pastures stockpiled after mid-August had a fall yield of 2600 kg/ha (2340 lb/acre). Earlier summer resting dates result in lower pasture quality in the fall as compared to later resting dates (Figure 2). The above-mentioned pasture that was rested in mid-July tested 10.3% crude protein and 58.5% TDN in the fall, while the pasture that was rested in mid-August tested 14.7% crude protein and 63.4% TDN in the fall.
Figure 1. Summer Resting Date and Fall Pasture Yield
The yield/quality relationship of stockpiled pasture is similar to that of first cut hay; the longer the stockpile is allowed to grow, the more yield is accumulated but quality is reduced. This relationship is useful to the producer, since a stockpiling management program can be designed to produce the optimum combination of yield and quality to suit the livestock that will be grazing in the fall. For example, a producer wishing to graze dry beef cows in November and December would use a management system designed to produce the maximum yield possible as long as the quality was sufficient to maintain the dry cow. A producer wishing to place weaned calves or lambs on fall pasture would accept a lower pasture yield to ensure the highest quality pasture possible for that class of animal.
The management system imposed prior to the stockpiling period can vary greatly depending on the individual situation. For example, to achieve very high yields in the fall, a single cut of hay or silage can be taken in early July and the stand is then left untouched until fall. Other situations may involve one cut of hay (or silage) and one or two grazing passes before the rest period begins, or several grazing passes prior to the rest period. This prior management will vary with the amount and type of stored feed required for winter and with the type of livestock to be grazed in the fall. One important concept to consider is that all forage land, not just permanent pasture, should be considered as a potential fall grazing area.
Figure 2. Summer Resting Date and Fall Pasture Protein Levels.
Any grass can be used for stockpiling, however, some species are better suited to certain systems. For example, species that tend to have slow regrowth such as bromegrass and timothy are best suited to systems where the summer rest period starts early and the regrowth period is long. These species would likely provide only one or two harvests (hay, silage, or pasture) prior to the summer resting date, which would occur sometime in July. Grasses with rapid regrowth such as orchardgrass and meadow bromegrass are best suited to shorter regrowth intervals prior to fall grazing. These species should provide three or four grazing passes or a cut of stored forage plus two grazing passes prior to the summer resting date which might range from late July to early September depending on the location. Reed canarygrass is intermediate in regrowth to the above species and tends to fit best with long to intermediate regrowth periods. Tall fescue has rapid regrowth (almost as fast as orchard) but will work with either long or short regrowth periods. Tall fescue has an additional benefit since it has been shown to have higher levels of TDN (energy) in late fall (November) than other pasture grasses. Bluegrass pastures should be allowed an intermediate rest period to allow the roots to strengthen and to provide sufficient volume for fall grazing.
The growth habit of the plant should be considered when deciding what type of management to use. Grasses that do not form a true stem in the regrowth, such as orchard and meadow brome, tend to lodge and shade themselves out when excessive regrowth occurs. Shorter rest periods are best for these species. Grasses that form a stem in the regrowth and are more upright in their growth habit, such as tall fescue, reed canary, and smooth brome, will stand up better in wet fall weather or after snow. Where long regrowth periods are desired, the upright species should be used.
In all cases, phosphorus and potassium applications should be based on OMAF soil test results and recommendations from an accredited laboratory. Additional nitrogen may be beneficial, although the response to nitrogen on both clipped and grazed plots has been variable. On productive pastures with high organic matter levels, the addition of 50 kg/ha (45 lb/acre) actual N in summer was shown to be only marginally profitable. Also, summer applications of nitrogen should only be considered when soil moisture is sufficient to generate a response.
Stockpiled forage can be used anytime there is a need for it and soil conditions are suitable for grazing animals. Usually, livestock are moved from regular pasture fields in September or October onto forage that has been stockpiled. Grazing can continue into December in most of Ontario or until the snow is too deep for grazing. Stockpiled forage can also be left in the field until spring or until a mid-winter thaw melts enough snow for grazing to resume.
Wet fall weather, interspersed with freeze-thaw conditions, results in a reduction of yield in stockpiled forage. Forage quality also drops during wet fall conditions. Data from New Liskeard has shown that stockpiled forage yield drops by about 3 to 5% during the month of October but this varies widely depending on the weather. At New Liskeard, crude protein dropped by about 30% from early September to early November, but TDN levels only dropped by 5 to 10% during the same time period (Table 1).
Table 1. Effect of Summer resting Date and Fall Harvest Date on Quality of Stockpiled Grass Pasture (Average of 1994 to 1996)
Research at New Liskeard with weaned lambs has shown that stockpiled pasture managed for high quality and moderate yield provided average gains of 126 grams/head/day (0.28 lb/head/day). This pasture had a carrying capacity of 1,100 lamb days per hectare (440 lamb days/acre) (meaning 1,100 lambs would require 1 hectare of stockpiled pasture per day). Lamb gains were highest in October and lowest in late November and December. When stockpiled pasture was managed to provide maximum yield (but lower quality), lambs gained an average of 86 g/head/day (0.19 lb/head/day), but the carrying capacity of the stockpile was much higher, averaging about 1,750 lamb days per hectare (700 lamb days per acre).
Research with dry beef cows (Elora Beef Research Centre and the New Liskeard Agricultural Research Station [NLARS]) indicated that a high volume, moderate quality (mid-July rest date) stockpile allowed significant increases in fat cover, body condition score, and body weight. This pasture provided 150 cow days per hectare (60 cow days per acre). Pastured dry cows in snow free conditions gained significantly better than hay-fed housed cows. In moderate snow and winter exposure, performance was similar between pastured and housed cows. Some pastured cows lost body condition during severe weather. In this trial, cows with at least 50% British breeding performed better in winter grazing conditions.
Animal performance is a function of diet and energy output. An economical shelter is allowing controlled access to a woodlot or a windbreak. Wind shelters are essential for extended season grazing to be successful when cold temperatures are accompanied by winds and snow cover. Ensure that livestock are grazing reasonably close to naturally sheltered areas during late fall and winter, or construct fixed or movable windbreaks in the areas of grazing.
Assess forage availability before solid snow cover since it is difficult to judge forage availability when there is snow on the ground. If sufficient forage is available (at least 1500 kg/ha or 10 to 12 cm in height; 1350 lb/acre or 4 to 5 inches of height), sheep can graze in 5 to 10 cm (2 to 4 inches) of relatively loose snow while cows can graze through up to 15 cm (6 inches) or more of snow. When snow is on the ground, stock should be moved more frequently but more residual forage should be left on each paddock. When there is snow cover, paddock size must be decreased, as larger paddocks allow excessive trampling to occur and the trampled snow can refreeze into a crust.
Strip grazing or rotational grazing is recommended when snow cover is present. Livestock should be limited to a few days (up to a week) of forage at one time so the use of temporary fencing is recommended. Fencing can be set up for a large area prior to the ground freezing, or portable posts can be placed daily or as required. In frozen ground, portable posts can be placed using a portable cordless drill to form a pilot hole, or by using a sturdy step-in post with a sharp point. The success of plastic posts varies, as some may shatter when installed in cold temperatures.
Watering stock on fall pasture is a concern in freezing temperatures. Even in November, pasture forage is between 50 and 70% moisture. Hauling water is an option, as is pumping from a pond or stream. Sheep have low water requirements in cool weather and dry ewes water requirements can be supplied from only good quality stockpiled forage. For beef cows a water source is essential, whether it is liquid water or snow. Provide about 20 – 25 litres (5 gallons) of water per day in cold weather (equivalent to 20 – 25 kg [44 to 55 lb.] of snow).
After three years of fall clipping or sheep grazing, forage yields were either not affected by fall harvesting or tended to be higher when the fall harvest was taken in November as compared to September. Research in the UK and preliminary results from NLARS indicate that yield might be marginally reduced in the following year. For the greatest protection against winter-kill, hardy species such as reed canarygrass and bromegrass can be used for stockpiling. Rotating the areas that are stockpiled from year-to-year will also reduce any risk of winterkill.
The risk of sod damage (pugging) is also a concern. Pugging is of greater concern on clay and clay-loam soils as compared to sand or sandy-loam soils. The grazing time allowed on a given paddock should be limited to reduce pugging. Pugging is not a concern once the soil surface is frozen. When there is a high risk of pugging, stock can be removed and fed on a sacrifice area and then returned to pasture when the pugging risk is lower. Soil compaction on wintering grounds has been a problem in some research. The animal load on a grazed pasture is much less than on an exercise or feeding yard, so compaction is of less concern.
Stockpiled pasture can be a low-cost source of forage for livestock during the fall and winter months. By changing management practices, the stockpiled forage can provide high yield and lower quality or high quality and lower yield. This response is controlled mainly by beginning the summer rest period at different dates. Producers can tailor the type of stockpiled forage to livestock requirements. Managing animals on stockpiled pastures requires rotational or strip grazing with moves every few days. Although experience has indicated little concern with soil compaction or increased winterkill from fall grazing, use caution in wet conditions or on heavy soils.