When you begin planning for your forage needs, you need to consider your options and the factors that affect your ability to produce and store quality forages. These factors include the amount of land you have available, the fertility of the soil, the supplementation options available to you, and your storage facilities.
There are four questions you must answer:
How much forage/feed is needed?
2. Where to store the forage/feed? (land resources, cost per ton of recovered dry matter)
3. Storage capacity – How big?
4. Forage/feed delivery – How to feed the herd efficiently - labor/shrink
The factors that influence your forage needs are the number of cows you are feeding as well as their size and level of production. You can calculate forage needs for heifers as half of that of a mature cow.
To estimate the forage needs of your cows, you will need to consider the following:
- What is the dry matter intake of your cows?
- What percent of intake is forage? Generally, we use 2 1/2 % of body weight to calculate forage intake.
- What about losses on the farm?
Sources of losses:
- Storage - fermentation, liquid run-off, gases, birds, rats, wind, water,
- Field losses
We have a 100 cow milking herd with 18 dry cows and 8 springing heifers, average body weight of 1400 lbs.
With forage intake at 2 1/2% of total body weight:
= 1400 lbs. x 0.025 = 35 lbs. forage DMI/cow
Estimate total forage intake for herd for the year:
= (35 lbs. x 126 head x 365 days)/2,000
= 805 tons forage dry matter
Lets say you feed a ration consisting of 75% corn silage 25% dry hay:
Corn silage = 805 tons x .75 = 604 tons DM
= 604 tons/.35 = 1725 tons as fed (65% moisture)
Alfalfa hay = 805 tons x .25 = 201 tons DM
= 201 tons/.85 = 236 tons as fed (15% moisture)
Source: R E James, Dept of Dairy Science, Virginia Tech