Why Should Forage Testing Be Done?

— Written By and last updated by JoAnne Gryder

hay-samplingMany livestock species use forages as their primary source of nutrition. Therefore, it is important to provide animals with the best quality forage available. By paying close attention to the quality of forages, you ensure healthy animals and minimize the costs of purchasing concentrate feeds.

Forage quality refers to the forages potential to meet the nutritional needs of a particular animal. A hay that meets all the nutritional needs of a pleasure horse would not meet those of a lactating dairy cow. Make sure to keep the needs of your animal in mind when reviewing the different ways of evaluating forage quality.

The stage of maturity at harvest plays a major role in determining the quality of a forage. Early in the growing season, forage plants move into their vegetative stage, characterized by leafy growth containing high concentrations of starches, sugars, proteins, and minerals. As the growing season progresses, plants enter the reproductive stages, characterized by elongated stems and developing seed heads. The dry matter in these mature plants has a lower proportion of nutrients and a higher proportion of plant fiber. The greater the fiber content of a hay, the less digestible it is, and the less an animal will consume before it fills its stomach. Therefore, the best hays contain a high proportion of leaves and few seed heads or stems.

Hay quality will also depend on how the hay was harvested, handled, and stored. Ideally, to preserve nutrients, hay should cure in dry, sunny weather as quickly as possible. Once it’s at the proper moisture content (15 %-18%), it should be taken from the field and stored in a dry, well-ventilated area. Hay not harvested and stored under these conditions may lose nutrients or get moldy, both of which dramatically lower quality.

Weeds often have poor feed value, and some species are toxic to livestock. High quality hay comes from healthy forage stands with few or no weeds. Hay balers occasionally pick up stray foreign objects, such as trash or broken machinery parts. These pose a real threat to animal health, so high quality hay must be free of foreign material.

Forage testing is used to estimate the nutritional value of forage for livestock rations. The common practice of collecting samples from the ends and edges of bales can cause the nutritive value of forage to be underestimated. Decayed and low-quality leached forages are often found on the outer edges of weathered hay bales. Cattle often reject this hay when they have access to more palatable forages in other parts of the bale. The ideal method of sampling hay bales is to use a bale probe. A number of probes are available; most probes cut a 1-inch-diameter core from the bale.

When sampling, round bale cores should be taken midway up the side of the roll and toward the center of the bale. Sampling near ends or bottoms of bales may not yield a representative sample. Remove the outer ½ inch of the bale surface before sampling so the sample will not be contaminated by dust and debris from the field. Next, drill or core into the bale 12 to 18 inches deep. Carefully pour the sample into a container. Good sample containers include manila mailing envelopes, sealable plastic bags (only if dry) and small paper sacks (fertilizer and feed sacks are not appropriate sample containers). Continue sampling four to five other bales from the same field and cutting. Mix the samples thoroughly and submit this composite sample to the laboratory along with the laboratory submittal form.

The process of collecting samples from square hay is to take sample cores from the ends of bales toward the center. First, remove the outer 1/2 inch of hay. Drill into the bale 12 to 18 inches deep. Carefully pour the sample into a container. Continue sampling six to eight other bales from the same field and cutting. Mix the samples thoroughly, label the composite sample, and submit it to the laboratory with the submittal form.

If you need help with taking forage samples, you can call the Wilkes Cooperative Extension Office at 336-651-7348.