Edward B. Rayburn Ph.D.
West Virginia University
Extension Forage Agronomist
A 12-month forage system is an integrated, year-round, forage production, and livestock nutrition management plan. This plan should provide a year-round forage supply in the quantity and quality needed by the livestock, as inexpensively as possible. In developing a 12-month forage system we need to determine the farm's forage budget. The forage budget is an accounting of the annual forage production and animal forage requirements.
Forage production includes pasture, hay, haylage, corn silage, and grazed corn stubble. By identifying what forage crops are grown, the acreage of each crop, and the average crop yields, you can estimate the annual forage production. Estimate forage production in tons (t) of 90% dry matter hay equivalent (HE) per acre (/a). You can use known production or estimated yields. Using HE is an easy method or you can use dry matter yield. Divide corn silage yields by 3 and haylage yields by 2 to estimate HE yields.
When yields are unknown, use an average pasture and hay yield of 2.5 t HE/a. Under poor management, these yields may run 1.5 t HE/a. Under good management, yields may exceed 3 or 4 t HE/a. On poor soils, corn silage yields will be comparable to well-managed hay yields. On good soils, corn silage may yield 50% more than hay.
For each crop enter the acreage and average HE yields in the "Forage Production" table on the "Annual Forage Budget Work Sheet". Multiply the acreage by the yield to estimate the total yield from that crop. Add the crop yields to get the total estimated forage yield.
Forage requirement is determined from the number and size of the animals on the farm. List the number of animals by livestock class in the "Forage Requirement" table. Estimate the average body weight (BW) of the animals in each class. Multiply the number of head times the average BW to get the total class weight. Add the class weights to get the total herd BW.
Cattle and sheep normally consume about 2.5% of their BW in forage dry matter each day. Sheep lambing more than once a year require 3.0% to 3.5% of BW. Dairy cattle need more feed but the additional feed is usually provided as grain.
There are losses when harvesting forage, when feeding stored feed or pasture, and when hay is used for bedding. Forage requirements should be increased at least 10% to account for these losses. On an annual basis the tons HE required by the herd can be estimated by multiplying the total herd BW by 0.0055. Use 0.0066 to 0.0077 for sheep lambing more than once a year.
Carrying capacity is the number of animals that can be fed on the forage produced by the farm. Estimate the herd size as a fraction of the farm's carrying capacity by dividing the annual forage requirement of the herd by the annual forage production. This ratio should be less than 1.0. If this ratio is greater than 1 more feed is required than is expected to be produced. Additional feed will need to be purchased. A rule of thumb in dry climates is that the stocking rate should be 0.85 of the farm's carrying capacity, to allow for drought years. In moist climates where hay is plentiful, the optimum stocking rate may be higher.
Forage production and requirements vary over the year depending on the forage and livestock management used. The cycle of forage production in West Virginia and the forage requirement for different livestock enterprises are listed in Table 1 by two-month periods.
Forage budgets are beneficial for estimating the pasture and hay needs on a farm. Table 2 shows an example of budgeting the requirements for pasture, hay making, and hay feeding for a spring-calving cow herd using cool season forages for pasture and hay.
To budget the flow of forage production and requirement, use a copy of the "Annual Forage Budget Work Sheet" (p 5716) and the following example. On the "Forage production" line (1) enter the percentage of the crop available in each period from Table 1. On the "Forage requirement" line (2) enter the period's percentage of the annual forage requirement for the livestock enterprise. It is assumed that the grazing needs of the herd will be met first if pasture is available. Subtract the forage requirement from the production to determine the values to be entered in the "Excess forage" line (3). When the value of "Excess forage" is positive, this is an estimate of the forage available for harvest. It is the fraction of the total annual production available in that period. To estimate the acreage available for harvest, divide the "Excess forage" (line 3) by the respective period "Forage production" (line 1). Where forage yield is similar across fields, this is the percentage of acres to be harvested. Where there are differences in forage production between fields, hay should be made on the most productive fields to reduce machinery costs per ton of hay. In this case a smaller percentage of acres will need to be hayed.
When the value of "Excess forage" is negative, production is less than requirements and stored forage must be fed. Sum the positive values of the "Excess forage" periods (24+8+2=34) in line 3. Divide the negative "Excess forage" values for each period by this total. This is an estimate of the fraction of hay that will be needed in each of the two-month periods.
Forage budgeting is useful in identifying how management can be changed to better balance forage production and use. If the herd size is equal to or greater than the carrying capacity it may be advisable to reduce the herd size. Where the feed requirement peaks when pasture production is low the manager should consider alternative forage or livestock management to reduce harvested feed cost.
|Table 1. Forage Production and Requirement by two-month periods.|
|Forage Type||Forage production % total||Livestock Class||Forage requirement % of total|
|Cool season forages||42||26||22||0||0||10||Dairy, year round||17||17||17||17||17||17|
|Warm season||16||68||16||0||0||0||Dairy, seasonal||19||18||17||16||11||19|
|Stockpiled tall||42||13||0||35||0||10||Cow calf, spring||18||18||20||14||14||16|
|Corn stover||0||0||100||-----||-----||0||Cow calf, fall||14||14||16||18||18||20|
|Uniform soils||50||33||17||0||0||0||Summer stocker||27||33||40||0||0||0|
|Sheep "star" lambing||17||17||17||17||17||17|
|Table 2. Forage Budget by two-month periods for a spring calving cow herd on cool season forage|
|Excess forage (1-2)||24||8||2||-14||-14||-16|
|Hay to make (3/1)||.57||.31||.09|
|Positive excess forage periods||24||8||2||0||0||0|
|Sum of "Excess" forage = 34|
|Negative "Excess" forage periods||0||0||0||-14||-14||-6|
|Hay to use (% of crop) (7/6)||.41||.41||.18|
Programs and activities offered by the West Virginia Cooperative Extension Service are available to all persons without regard to race, color, sex, handicap, religion, age or national origin. Cooperative Extension Work in Agriculture and Home Economics, West Virginia University and the United States Department of Agriculture, Cooperating. Rachel B. Tompkins, Director, Morgantown, West Virginia. Published in Furtherance of Acts of Congress of May 8 and June 30, 1914.