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Will my hay supply be enough?

By Roger Gates

Whitfield County CEA

Livestock producers who have had to purchase hay in dry years do not need economists to describe the impact of supply on price.  The value of an adequate supply becomes increasingly obvious as winter transitions to spring if pasture growth is slow or delayed. At least four factors contribute to whether this year’s supply will be adequate:

Hay Inventory

Measuring the supply of hay on hand would seem to be a straightforward matter of counting the number of bales and knowing the average weight. Published weights of “standard” size bales can range from less than 600 pounds to more than 1500.  Density of the crop and compaction of the bale contribute to variation. Actually weighing a representative sample of bales (weighing a truck or trailer loaded and unloaded) might be a wise investment… variation from assumed values can be considerable.

Hay moisture content is also variable. Hay should be below 15% to store safely without risk of heating and molding, but under dry conditions, bales may contain less than 10% moisture.  For a 1000 lb bale, that difference amounts to 50 pounds.  Information on moisture content alone could justify the cost of a obtaining and submitting a forage sample.

Standing Forage

In addition to counting bales and assigning weights, remaining grazable forage should also be included in the feed supply inventory.  Past grazing records and experience will help in assigning values for dormant perennial pasture forage. Estimating the number of “cow grazing days” may be the most useful approach to estimating the feed available.  Intentional stockpiling and intensive allocation of pasture forage with subdivision using temporary fencing will increase the efficiency of grazing and extend the quantity of feed available.


Estimating demand is the “balance” to determine whether the hay inventory is sufficient.  In simplest terms it is knowing how many animals will need to be fed, how much hay they will eat and how many days hay will be provided.  Hay consumption is controlled to a large degree by animal size.  Accurate estimates of animal weights will improve the accuracy of hay consumption estimates.  Without a scale, knowing the pay weight of culls may serve as an estimate of mature cow weights.  As a “rule of thumb” dry cows will meet their nutritional needs by consuming from 2.0 to 2.5% of their body weight as hay dry matter.  For example, a 1300 lb cow will consume 26 to 32 pounds daily.  If hay contains 10% moisture, that will be 29 to 36 pounds.  Younger, lighter weight, animals will consume proportionally less.

Hay quality is extremely variable.  Cattle are well adapted to “process” fibrous feeds like pasture and hay; but that capacity can be limited by the composition of the fiber fraction.  The rumen might be compared to a “processing vat” that has a fixed capacity.  When it’s full, no more feed can be added until some of the contents are removed.  Removal occurs through digestion and passage.  In basic terms, the more mature and fibrous a hay is, the slower the digestion and passage rates are.  Slow removal from the “vat” reduces intake.  While lower intake might make a particular hay “last longer,” the consequences for animal performance are not beneficial.  Mature hay is sometimes deficient in protein.  Without proper supplementation, digestion will be further limited and intake reduced.

Properly sampling and testing the hay supply will identify nutrients that will be adequate or better as well as potential deficiencies. A summary value, Relative Forage Quality or RFQ, can provide guidance about hay intake, which is needed to forecast the adequacy of the hay inventory.  An RFQ value of 100 is comparable to full-bloom alfalfa hay.  Hay of that quality should support adequate intake for dry, pregnant, mature cows.  RFQ values much below 100 will be result in lower intake (potentially below 2.0% of body weight) which will compromise performance.

Many producers have more than one “lot” of hay that is available to support the herd.  A “lot” is hay refers to one cutting from one field. Knowing the nutritional value of different hay sources will allow wise decisions to be made about which hay to feed to which animals to meet nutrient requirements least expensively.

A hay test that identifies moisture content and nutritional value of the hay supply is a wise investment.  Most County Extension office have equipment available and can assist in obtaining representative hay samples.  Results for samples submitted to the UGA Feed and Environmental Water Lab will often be available in less than one week.


With estimates of hay quantity, animal consumption and a target for the number of days hay will be fed, supply and demand can be compared to determine whether the hay on hand will last…  EXCEPT…

No feeding program is 100% efficient.  Losses can accumulate in storage, and during feeding. Animal selectivity will also limit consumption to less than what is fed.  Oklahoma State University Emeritus Extension Animal Scientist, Dr. Glen Selk, suggests that waste can vary from 5 to 20% and suggest using a figure of 15% when predicting hay requirements.

A substantial deficit in the hay supply materializes in the hypothetical example described in the following tables:

Cattle Inventory

Average Weight


Intake Rate


Daily Intake (lb) Feeding period (days) Total Hay Demand (lb) Waste Allowance +15% Hay Supply Needed (lb)
43 mature cows 1300 2.2 28.6 90 110,682 16,602 127,284
13 replacement heifers 900 2.5 22.5 110 32,175 4,826 37,001
Mature bull 2400 2.0 48.0 75 3,600 540 4,140
Yearling bull 1350 2.3 31.1 110 3,421 513 3,934

Hay Inventory



Bale weight (lb) Moisture


Bale DM


Hay Supply Available (lb)
1st cutting,

T Fescue

127 850 12% 748 94,996
2nd cutting, T Fescue 88 750 14% 645 56,760
Inventory Shortage 20,613

The hay shortage of over 10 tons represents the hay needed to feed 43 cows for about 2 weeks.  Favorable weather might allow the producer to shorten the winter feeding period from 90 to 75 days.  On the other hand, severe weather, or a spring dry spell might result in the need for even more feed.  Projecting supply and demand before or early in the hay feeding season would allow locating additional feed, hopefully at a reasonable cost.  Facing an unanticipated feed shortage in the spring could require unplanned herd reduction sales or purchase of replacement feed at high cost.