Estimating Hay Needs

Mark Z. Johnson, Oklahoma State University Extension Beef Cattle Breeding Specialist

 

Some basic rules of thumb to follow when determining the hay supplies you will need to sustain your cow herd over the next few months.

 

  1. Determine your average mature cow size. This can be done by weighing your 4 – 7 year old cows and calculating the average weight. From mature cow size, we can approximate the amount of forage dry matter cows will need to consume per year or per day. For example: a 1,000 pound cow will consume about 26 pounds of forage dry matter per day. A 1,400 pound cow will consume about 36.4 pounds of forage dry matter per day.
  2. Determine your cow inventory

 

  1. Estimate the amount of time you expect to be feeding cows.

From this information you can calculate the total amount of hay needed. For example: 100 cows weighing 1,400 pounds will consume about 3640 pounds of hay per day. We should take into account that a certain amount of the hay fed will be wasted and there will be a certain amount of spoilage of each bale fed that won’t be consumed. With this in mind we will add another 10% to the daily total to bump it up to about 4000 pounds (2 tons) per day.

 

Remember the amount of hay wasted or spoiled could be higher. If we are feeding hay from last year expect a higher percentage spoiled in each bale.

 

If we are expecting to feed hay from mid-October to mid-May, that is approximately 200 days of hay feeding. 4000 pounds of hay needed per day x 200 days equals a total of 800,000 pounds (400 ton) of forage dry matter that cows will consume over this time. If we are feeding or buying large rounds with an average weight of 1,250 pounds that equates to 640 (800,000 divided by 1,250) big bales needed to sustain the 100 cows.

 

If possible, purchase hay by the ton. It leads to less error in securing the amount of hay you will need to purchase or have on inventory. If buying hay by the bale is your only option, make sure to weigh enough of the bales to have an accurate representation of bale weight.  Also, take into account the amount of spoilage of each bale. One of the upsides of hay baled this summer (and the drought we are dealing with now) is less spoilage of warm season grass hay baled in the summer of 2024. 

 

Other factors such as weather, stage of gestation or lactating versus dry cows will obviously impact nutritional requirements of cows from day to day. Provide hay and other nutritional supplementation accordingly.


Oklahoma State University, in compliance with Title VI and VII of the Civil Rights Act of 1964, Executive Order 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, sex, age, religion, disability, or status as a veteran in any of its policies, practices or procedures. This includes but is not limited to admissions, employment, financial aid, and educational services.  References within this publication to any specific commercial product, process, or service by trade name, trademark, service mark, manufacturer, or otherwise does not constitute or imply endorsement by Oklahoma Cooperative Extension Service.