Agronomy Mimeo 100
                                   

                          (February 1991)

    

    ECONOMIC CONSEQUENCES OF FORAGE HARVEST AND STORAGE LOSSES

     Foremost among the improvements needed in forage crops production and

management is increased forage quality.  A high-quality forage is one that

is consumed in large amounts per unit of time and contains a large amount 

of digestible energy.  These qualities permit intake of digestible energy 

in amounts in excess of maintenance requirements. The greater this 

difference, the higher the animal output will be.

     Forage quality is closely associated with maturity of the herbage.  

Very young herbage may reach 70 percent digestibility.  Alfalfa-grass 

mixtures in Ohio (Hibbs and Conrad, 1975) at prebud stage had 66.8 percent

digestibility, declining at a rate of 0.28 percent/day to 55.8 percent at 

maturity.  Much of our hay and hay crop silage is harvested at growth 

stages that average 55 to 60 percent digestibility -- seven to nine 

digestibility units below the practical maximum.  This results from

limited harvesting capacity per day, weather delays and damage, and a 

lack of appreciation by farmers and many farm advisors of the importance 

of forage quality for animal production.  Furthermore, physical and biological

losses experienced with current harvest and storage methods commonly reach

20 to 25 percent of dry matter and an even greater decrease in digestibility.

     Losses during harvest and storage can have disastrous economic 

consequences for the farmer. Data presented by Hodgson (1980) illustrates 

the impact of three hypothetical, yet not unrealistic, loss levels on dry 

matter digestibility (DMD), digestible energy (DE) consumption, and milk 

production (Table 1).  Loss level (a) is routinely experienced with our

best hay-making procedures and favorable weather during harvest.  

Loss level (b) could be expected if the cut forage is rained on once and 

loss level (c) occurs after more than one wetting by rain.  The data are 

for alfalfa cut at first bloom.  Delayed harvest plus harvest losses 

compound the economic loss.

     Hodgson's data indicate that, even with good weather during harvest 

and very good hay-making procedures (loss level a), we are realizing only 

about 56 percent of the potential milk production that would be possible 

if we could get all the digestible energy in the standing crop into the 

cow.  With poor weather, Hodgson indicates that we may realize only 40 

percent, or less, of potential.  The inability of dairymen to exploit the

potential milk production per acre in alfalfa is very costly.  The value 

of the potential milk yield of bud stage alfalfa having 68% DMD is about 

$1340 per acre (milk valued at $13.60/cwt).  The value of milk production 

with best current harvest technology, as illustrated by loss level (a) 

in Table 1, is about $755 per acre; with loss level (c) the value declines

to about $105 per acre.  This clearly shows why farmers feed large

quantities of grain to dairy cattle. It also shows that there is great

opportunity to exploit forages more fully.  Hodgson points out that, in 

ration balancing, animal nutritionists usually value alfalfa hay at about

55% DMD, about equivalent to loss level (b) of Table 1.

Table 1.  Effects of post harvest losses on alfalfa quality and animal 

production.1 Loss Levels:  (a) 10% of dry matter and reduce DMD to 60%; 

(b) 15% of dry matter and reduce DMD to 57% and; (c)  25% of dry matter 

and reduce DMD to 50%
_______________________________________________________________________________
                                           DE/Day           Milk Produced3
   Loss          DMD         DE/Acre      Consumed                            
   Level          %          Mcal2          Mcal         lb/day       lb/acre
_______________________________________________________________________________
     a            60           7992         36.5          25.3        5549
     b            57           7171         31.2          17.2        3962
     c            50           5550         22.0           3.1         782    
_______________________________________________________________________________

1Alfalfa crop as harvested at first bloom yielded 3.7 tons/acre

2Mcal = megacalorie or 1 million calories.  It is used for expressing the

chemical energy in feeds and metabolic processes.

3Calculated for a 1430-pound Holstein cow.

     The potential milk production from a modest 3.7 tons per acre alfalfa

crop is about 9800 lbs per acre (Hodgson).  Dairymen generally obtain less

than half of that amount.  Furthermore, 3.7 tons per acre is not a very 

high yield by today's standards.  Thus, if dairymen were to obtain 

potential yields and achieve potential utilization efficiency, milk 

production per unit of land area could be increased several fold.  

While Hodgson's data are for milk production, liveweight gains by beef 

cattle follow similar trends in relation to forage quality.

     According to Hodgson, "Special emphasis should be given to reducing 

the excessive losses between harvest and feeding.  These losses are 

perhaps the most extreme losses in agriculture.  Very large quantities of

photosynthetically fixed energy are either lost or rendered less available

to animals by current harvest and storage systems." He further states, 

"Progress in increasing yield, pest resistance, or DMD in the standing 

crop by genetic means will have little payoff unless we are able to 

improve harvest and storage technology and reduce digestible energy 

losses.  With that improvement, increased forage yield and higher quality

in the standing crop will have a very large payoff.  

                            References

Hibbs, J. W., and H. R. Conrad.  1975.  Minimum concentrate feeding for efficient milk production. 
World Anim. Rev. 15:33-38.

Hodgson, H. J.  1980.  Forages, food, and energy.  In:  Report of the Twenty-Seventh Alfalfa
Improvement Conference, pp. 14-20.  USDA-SEA Ag. Reviews and Manuals ARM-NC-l9.

Prepared by:

 Dr. Lester R. Vough,  Forage Crops Extension Specialist