How's Your Forage Quality This Year?

Many years can be quite challenging for sheep and goat producers to manage forage quality in pastures and hay. Annual rainfall and temperatures can vary greatly from one year to the next. This can significantly impact forage quality, both on pasture and in hay, making the year's hay especially important to analyze in order to balance rations.

In some cases, forage fiber content limits the ability of animals to eat enough to meet their nutrient requirements. We refer to this as dry matter intake, the completely dry portion of a feed that animals consume. On the other hand, some years may have a spring that is exceptionally wet. Therefore, instead of fiber limiting dry matter intake, we now see that water content in pasture forages limits intake. This can also result in a general trend for lower-than-normal energy and protein levels. Therefore, sheep and goat producers need to consider forage analysis reports when balancing rations for the winter.

Most pasture forages contain 75 to 90% moisture, while dry hays usually have less than 15% moisture. We measure moisture content so that we can compare nutrient contents from different feeds on an equal basis. Let's look at an example that compares nutrient contents of grass pasture and grass hay on an as-fed basis versus a dry matter basis. The pasture and hay contain the same levels of protein, but we would not be able to determine this without comparing the forages on a dry matter basis.

Information taken from Determining Forage Quality: Understanding Feed Analysis, written by Dr. Robert VanSaun

Whenever we compare the forages on an as-fed basis, or in other words, as the forage is fed to animals, we see that dry matter is 20% for pasture and 90% for hay. Looking at the protein content of the forages, pasture is 2.2 % protein, and the hay is 9.9% protein as fed. However, these forages actually contain the same percentage of protein, 11%, when you remove the water content and consider the forage on a dry matter basis.

The next columns in the table discuss fiber contents expressed as NDF (neutral detergent fiber) and ADF (acid detergent fiber). Neutral detergent fiber measures all the fiber components in a forage. These components make up the plant cell walls and include hemicellulose, cellulose, and lignin. As the NDF measurement increases, it indicates that the fiber content also increases. This causes dry matter intake to decrease, and the animals chew their cud for longer periods. Acid Detergent fiber measures the highly indigestible fibers, and as this number increases, digestibility decreases.

To put this into perspective, a legume forage is considered of good quality if the NDF is below 40%. Anything above 50% would be considered poor quality. On the other hand, high-quality grass forages should have an NDF of less than 50%. Low-quality grass forages have NDF levels higher than 60%.

The only way to correctly evaluate forages is to have them analyzed. This enables sheep and goat producers to accurately balance rations, thereby enhancing feeding efficiency and profitability. Underfeeding nutrients results in slower growth rates, decreased milk production, and could even impact lambing or kidding percentages. Overfeeding nutrients can result in wasted money by providing more nutrients than the sheep or goats actually require.

The first step to analyzing forages starts with collecting a representative sample. Forage test results must represent what the animals eat. Samples should be collected from each field and each cutting. Test results vary greatly throughout the year! Use a bale core sampler and insert it to its full depth into the end of each small bale or the rolled side of each round bale being sampled. Collect at least 20 samples from each field and cutting. Mix samples from each group separately in a clean bucket and place them in an airtight plastic bag. Label each bag before sending to your local forage testing laboratory.

Once you receive the forage test results, you can then balance rations to make sure sheep or goats receive adequate nutrients throughout different production stages. For more information on forage testing and balancing rations, contact your local Extension Office or a nutritional consultant.