The goal of the dairy heifer rearing system is two fold – economical rearing of well grown heifers. For too long dairy producers knew little of the cost to rear dairy heifers and did little to evaluate the influence of management during the rearing period on later production and profit. However, the professional dairy heifer grower has caused the industry to focus more on these challenging goals. Undoubtedly pasture based systems play an important role in heifer rearing systems, particularly in the central and eastern U.S. However, the mention of pasture frequently results in the drawing of battle lines between those advocating pasture and those using dry lot feeding systems. Some pasture aficionados praise the glowing benefits of pasture systems and denounce those who raise heifers in dry lot systems. Meanwhile the dry lot advocates are so entrenched in their management styles that they automatically quit listening when they hear the word “pasture”.
The best examples for pasture systems exist in New Zealand, Southern Chile, Argentina, and similar climes that have cool temperatures and frequent, moderate rainfall. The worst examples are range management systems requiring extensive land bases exceeding 50 acres per animal which support little more than maintenance. In most of the U.S. the role of pasture in heifer feeding systems is probably in between these extremes. It’s important to realistically evaluate the advantages and liabilities of each system and determine how best to minimize the risk of their shortcomings.
Pasture systems offer the opportunity for better health for the growing heifer, and the chance to use more marginal land for productive purposes. Improved economy of rearing is widely touted as a benefit. A custom heifer grower in Minnesota (Rudstrom, 2002) compared heifers grown on feedlot and pasture systems. Heifers averaging 480 lb. were divided into four groups of 36 each. Two groups were reared on feedlot systems and two were put onto alfalfa pasture from May 13 to October 5. Feedlot heifers were fed a TMR and heifers on pasture were rotationally grazed and received some supplementation. Rates of gain were similar for both systems. Results are shown in Table 1. Net costs were $1.49/heifer/day for the feedlot system and $.95/day for those on pasture. The greatest differences were due to feed, machinery and labor costs. In a simulation study, Toro (1987) found that when pasture contributed 80% of requirements during the grazing season, total feed costs could be reduced by $116/animal over the rearing period. However, it should be noted that in many areas of the U.S. housing facilities must be used during the colder months of the year. This results in a duplication of systems and the added costs of building confinements facilities in addition to pasture. Pasture systems also has liabilities. Carrying capacity, length of the grazing season and timing of feed nutrient supply with requirements for animal growth are heavily weather dependent. Growers must use a reasonable estimate of costs for fencing, fertilization and land. Provision of suitable water is often a challenge. In nearly every system plans must be included for provision of supplemental nutrients when pasture growth is inadequate.
|Total $||$/head/day||Total $||$/head/day|
|Fencing, bunkers, water||---||---||811||0.08|
Successful use of pasture systems is challenging because the manager must excel in both heifer and forage management. He or she must have the skills to manage systems which rely on decision making guided by more subjective information than those relying on dry lot systems. Managing the risk of insufficient nutrients at the desired time and accomplishing this with minimal labor is the subject of this paper.
Growers considering adopting a pasture based system must consider a wide range of factors including:
Physical facilities include fences, travel lanes and heifer working facilities. Perimeter fencing needs to be a barrier fence which offers minimal risk of escape. Economical designs can be constructed of 3 or 4 wires with one or more electrified. One Virginia heifer grower uses 4 wires. The bottom wire is barbed and 18” from the ground, the next is smooth electrified and 12” higher, and the remaining are barbed wire at 12” intervals. High tensile fencing with 4 or 5 wires and several electrified is an effective barrier. Electrified wires are desirable as they discourage unwanted bovine suitors and dogs. The author has successfully prevented dogs and coyotes from entering the pasture by electrifying the bottom wire. However this necessitates controlling weed growth by moving or spraying fence lines with herbicide. Electric fence chargers should provide 5,000 volts or higher at low impedances (high resistance to shorting out) and short impulse time. Adequate grounding of electric fences is critical and it may require long ground rods, possibly linked in series, particularly when the soil is relatively dry.
Temporary fencing is essential in most pasture rearing systems depending on whether the system uses continuous or rotational grazing. Fencing using polywire, polyrope or polytape is effective in confining most animals. Continuous systems require grazing areas to be limited during lush growth and harvest of surplus as hay or silage. Rotational systems require moving fences, which can be laborious. Heifer rotational grazing systems need not be as intensive as those used for lactating dairy cattle since nutrient requirements are not as exacting for heifers. A Virginia heifer grower featured at the 2004 meeting is able to move these portable fences using a 4-wheeler and golf bag for holding the posts as shown in photos below.
Travel lanes must be constructed to prevent erosion which varies depending on topography and soil type. Fencing along travel lanes should be similar to perimeter fencing. Use of layers of varying density rock and cloth have been successful in maintaining lanes and preventing erosion as shown in the photo below.
Thoroughly evaluate the resources of the farm, including topography, soil type and climate. Immediately realize that it is highly unlikely that any establishment in the U.S. will be able to meet nutrient requirements exclusively with pasture as is done in New Zealand. Identify the liabilities of the operation’s resources and devise management strategies to overcome or minimize them. A primary consideration is identification of the most desirable forage species for the operation. This will dictate the ability to produce forage dry matter. Primary considerations are species, which produce reliably large amounts of dry matter, energy and protein.
If land is to be utilized for pasture, its use during the year must be maximized. How long is the grazing season? What species or combinations of species will enable extension of the grazing season and how can yields be optimized? Careful consideration of most desirable combinations of grasses and legumes and annual and perennial species can add days or even months to the length of the grazing season depending on location of the farm. Figures B and D on the next page represent forage availability in a normal year in two regions of the U.S. Zone B represents southern U.S. and Zone D conditions in the Mid-Atlantic and central U.S. Note differences in best adapted species and length of the growing season in each zone. In Zone B, grazing is possible year round with combinations of grasses, legumes and small grains. However, in the more northern states, grazing is probably limited under the best of conditions to no more than 6 to 7 months of the year.
The biggest challenge faced in the pasture system is reliably estimating the carrying capacity of the land. If land is to be utilized for pasture, its use during the year must be maximized to provide the best compromise between yield of animal growth and forage nutrient yield. Figure 3 shows the effect of grazing pressure on production per animal and per acre. Note that optimal growth per head is not the same as optimal growth per acre. Optimum growth per animal occurs at a point less than optimum for land utilization. When grazing pressure is low to medium, heifers graze on only the best quality forage. When pasture output is optimized at higher stocking rates, heifers are forced to consume some of the less nutritious growth and animal performance declines. This represents a challenge for
the heifer grower or dairy producer. Extremes in stocking rate are undesirable. Long periods of low grazing pressure lead to a loss of legumes in a stand and increased growth of weeds and less desirable species. Long periods of high grazing pressure result in temporary or long term decreases in forage production as root reserves of desirable forage species are depleted and plants die. For optimum grazing, one should maintain available forage at approximately 1,000 to 1,500 lbs. of dry matter / acre. This is the equivalent of a 3 – 4 inch high stand of blue grass/white clover or 6 – 8 inches of tall grasses and legumes.
Historically, continuous grazing has been the most popular grazing system since it is simple and requires little labor. Grazing pressure is adjusted by adding or subtracting animals or temporarily fencing off areas for hay harvest. However, continuous grazing is a land extensive system and low production of gain per acre makes it inefficient. In contrast, rotational grazing can dramatically increase animal performance and forage dry matter yield per acre. In heifer feeding systems, intensive rotational grazing systems are probably not necessary. Gains accrued from more frequent moving of fences do not offset the labor and fencing expense and convenient provision of water. Many heifer growing systems include some combination of both systems. A continuously grazed paddock may be used to house animals during the winter or during periods of drought to enable other areas to recover forage growth. Other paddocks are designed to enable movement of fences on less frequent interval of 3 to 14 days.
It is folly to think that dairy heifers can be raised in most regions of the U.S. without significant nutrient supplementation during some portion of the year. The nutrient variation of grazed forage species represents one of the greatest challenges of this system. In the more temperate areas of the U.S. protein concentrations can vary from 6% to levels exceeding 20% while the growing dairy heifer may require levels ranging from 12 to 18%. Similarly, energy values will range from those similar to corn silage to levels which more nearly resemble straw. Although heifer rearing regimes might tolerate some variation in growth, in today’s economic climate it’s important that heifers calve at an early age and with desired body size and condition.
When forage availability is adequate, but quality is lacking, provision of supplemental energy and protein through concentrate feeding is advised. At other times such as winter months or during severe drought, heifers require supplementation with both forages and concentrates. It is beyond the scope of this presentation to address adequately the supplemental nutrient needs of pasture-reared heifers. However, several important factors should be considered.
Pasture reared heifers require more energy than those in confinement due to their increased activity and exposure to environmental conditions, particularly during the winter. Research at Virginia Tech has shown that confinement reared heifers require 12 to 25% less energy than indicated by NRC. They are also less influenced by severe cold and wet weather. Therefore, managers of pasture reared heifers must make adjustments in nutritional strategies when environmental conditions are less than perfect. Factors such as cold weather, non-thermal resting areas, wind, rain, and snow increase demand for energy for maintenance thereby reducing that available for growth. Environmental conditions for heifer raised without housing may become so severe that it is not possible to maintain sufficient growth, even with substantial energy and protein supplementation. In summary, supplementation of rations with energy must be based upon observed growth of heifers during inclement weather and not what a computer program or table of nutrient requirements might indicate. Similarly, supplementation can often be reduced at considerable savings when pasture growth and environment are optimal.
Feed delivery to heifers is an afterthought on many dairy farms and heifer growing operations. It should cause minimal damage to pasture productivity, encourage desired consumption by the animals and foster improved animal handling and labor efficiency. Fence line feeders are quite effective. They can be combined with features such as headlocks or modifications which enable capture of animals and use of portable chutes for routine weighing, herd health procedures and reproductive management. They also facilitate drive-by feeding using mixer wagons and if properly designed, cause minimal damage to pasture productivity. Use of a total mixed ration offers considerable opportunity for labor efficiency and use of economical byproduct feeds and ensiled forages.
Provisions for feed storage must be considered as a cost of the pasture based heifer rearing system. Development of bale wrapping equipment and silo bagging equipment has greatly improved flexibility of supplemental forage storage systems for heifer growers. Stored forage can be located adjacent to “permanent paddocks” used for winter or summer drought housing. Grass or legume “baleage” can be stored for a cost of approximately $2/ton of forage. A 9’ by 200’ bag costs approximately $325 and holds 250 tons of dry matter. Commodity shed storage is desirable as it permits use of economical byproduct feeds. Careful attention to these details greatly increases opportunities to supplement pasture and assure growth during periods when pasture growth is inadequate.
Water availability is an important aspect of the efficient pasture management operation. It has a large impact on feasibility of the type of grazing system used. Options include wells, streams and ponds. Traditionally, pasture rearing systems have utilized natural sources of water such as streams and ponds. Use of streams is not a desirable option due to biosecurity risks involved and nutrient management concerns. However, water can be provided from streams when it is pumped to portable stock tanks using solar powered pumps. These systems can provide 600 to 1500 gallons per day at an initial cost of approximately $4,000 (Sinton, 2002). Solar pumps can also be used with strategically located ponds from which animals are fenced out. One heifer grower uses small spring fed farm ponds to which animals have limited access only by means of a fenced off concrete ramp as shown below. In rotational grazing systems, portable tanks are moved with the fence and water supplied via PVC piping. The limitation of such systems is freezing of piping during cold weather which necessitates the use of more permanent heated watering devices.
Provisions must be made to handle animals for routine procedures and reproductive management. Heifers need to be handled a minimum of 4 to 5 times between 4 months of age and calving. Necessary facilities include receiving, quarantine and those used for health and reproductive management procedures. Offloading animals into an unfamiliar environment is stressful. Facility design can help minimize stress by following several key provisions. Loading ramps and handling chutes should have solid side walls to prevent animals from seeing distractions outside the chute. Blocking vision will stop escape attempts and lower stress. Animal handling facilities should be quiet with a minimum of banging and clanging. Sudden loud noises discourage animals from using chutes and restraining devices. Quarantine facilities should exist on every establishment that receives purchased or contract reared animals. Animals should remain in quarantine for at least two weeks and preferably until results of disease screenings are known. Perimeter fences of these facilities should be substantial. Grandin (1996) describes considerations for minimizing animal stress during handling.
There are two options available for restraining animals – headlocks or a pen and chute system. Dairy producers utilizing headlocks are pleased to have their heifers trained to use headlocks prior to entering the milking string.
The focus of this presentation is to discuss means to implement pasture rearing systems which afford a high degree of labor efficiency. Special attention must be directed towards those tasks which require the most labor, namely forage management, provision of supplemental nutrition during times of poor forage growth and animal handling. Unfortunately there is no blueprint that can be used to design an effective pasture based heifer rearing system. Each producer must evaluate their resources and determine what is most desirable in their situation. The diagram shown below represents a pasture based heifer rearing system used by one Virginia custom heifer grower. It includes the comprehensive incorporation of feed and forage storage, ration delivery, travel lanes, supplemental water and both continuous and rotational grazed pastures that are also used for production of stored forage during surplus growth.
The following list provides items to guide dairy producers and heifer growers in considering what system best accomplishes the goals of desired economical growth.
Ultimately these components need to fit together into an efficient system, which enables the producer to achieve goals predictably and at low cost.
Agronomy Guide. 2003. Pennsylvania State University.
Chester-Jones, Hugh. 1996. Pasture systems for heifer replacements. In Calves, Heifers, and Dairy Profitability. NRAES – 74.
Gerrish, J. R., P. Morrow, K. Moore, M. Davis, and C. Roberts. 1994. Missouri Grazing Manual. Univ. of Missouri, Forage Systems Res. Center, Ag. Expt. Sta., Univ. Extension. USDA and SCS.
James, R. E. 1996. Maintaining heifer growth on pasture. In Proc. 1st National Professional Dairy Heifer Grower’s Conference. Pp. 91-101.
Rudstrom, Margot. 2002. The tale of two heifer-raising systems. Dairy Initiatives Newsletter Vol. 11. Issue 1. http://www.ansci.umn.edu/dairy/dinews/11-1-heifer-raising.htm.
Sinton, C. W. 2002. Demonstration and marketing of photovoltaic-powered water pumping systems in New York State. NY State Dept. of Agriculture and Markets, Ag. Energy Pilot Program.
Robert E. James
Professor, Dairy Management
Department of Dairy Science
Virginia Polytechnic Institute and State University