Matching hay quality to animal nutrient requirements

Feeding costs can account for over 50% of the cost of livestock production. Knowing your hay quality and animal requirements can ensure you don't waste that investment.

This article examines the nutrient content of grass or legume hay and the nutrient requirements of livestock. It offers suggestions on how livestock managers can utilize the hay effectively and efficiently.

Hay quality

Hay quality is measured in terms of energy, protein and digestibility. The higher the better.

Young, fast-growing plants contain more energy and protein and are more digestible than old, slow-growing plants that have gone to seed. Animals get more nutrients from the young plants still in that vegetative state than from older plants in a mature or reproductive state.

As a plant matures and gets a higher ratio of stem to leaf material, fiber content increases and the percentage of protein and energy decreases. Digestibility and feed intake also decrease, so the animal receives less quality and quantity of feed. That means early-cut hay is more nutritious than late-cut hay. Most hay should be cut between the late boot stage (inflorescence emergence from the leaf sheath) and full seed-head expression, well before flowers begin releasing pollen.

Feed energy is expressed in terms of total digestible nutrients (TDN) and feed protein is expressed as crude protein (CP). These can be estimated from the natural components that make up the hay (fiber, fat, carbohydrates and protein or nitrogen). The digestibility of the feed is estimated based on the relationship among feed components. This is made possible from information gathered in extensive studies on chemical components of feeds and the actual digestibility of the feedthrough animals. Although in-depth analyses using actual animals were used to define these relationships, routine laboratory analysis for only a few feed components can be used to estimate the quality of feeds.

The best way to evaluate your hay is to submit samples for laboratory analysis. The cost is about $25 to $35. For information on how to test your hay and a list of labs that analyze feed samples, contact your local Extension office. You can also request protein and energy values on the hay you purchase. One very good quality grass-legume hay contained 13.8% CP and 62% TDN. Another hay of lower quality contains 8.4% CP and 58% TDN. The large variation in quality among hays in Oregon makes it important for you to have an accurate estimate of your hay quality.

If you are unable to get a chemical analysis, record the cutting date or maturity and the amount of contamination by undesirable plants, which could decrease quality. You can use this information to help you feed out the hay later (see below).

Animal requirements

Once you estimate hay quality, match that with the animal’s requirements. Younger, fast-growing animals have greater requirements for their size than mature animals. Highly productive animals require more nutrients than animals merely maintaining weight.

Nutrient requirements of livestock have been investigated and results published by the National Research Council, and books and charts are available for beef and dairy cattle, sheep, goats, swine, horses, and more. These publications list requirements by class (steers or heifers, pregnant, lactating, etc.), weight and rate of gain desired.

Some example nutrient requirements are as follows.

  • A 500 lb, medium-framed steer calf gaining a pound per day requires 58.8% TDN and 9.5% CP in its diet.
  • A 500 lb, medium-framed steer calf gaining three pounds per day requires 85% TDN and 14.4% CP.

Animal requirements may change with time. A154-pound, mid-gestation ewe needs 9% CP and 55% TDN while a lactating ewe needs 15% CP and 65% TDN). See the publications for specific requirements for your animals.

Matching feed with animal requirements

Once you have identified the animal type and its requirements, make sure it is receiving adequate nutrients for animal health and productivity goals.

You may need to provide supplemental feed to make up the difference in nutrient content between forage and animal requirements. Consider the cost of supplements and the benefits of increasing animal performance. Be careful not to overfeed supplements to the point of replacing base forages (hay or pasture).

Stack hay in bays according to quality and as you use the hay for summering or wintering your animals, keep in mind the different requirements for the animals as discussed above.

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