PUTTING FORAGES TO THE TEST FROM PREVIOUS PAGE ers. Avoid long hay strands and large flakes. Schnakenberg said it is a good idea to keep in mind sample variance, collecting samples at random. “Sample as close to feeding or as close to the point of sale as possible, allowing seven to 10 days for test results,” Schnakenberg said. Visit www.foragetesting.org for a list of NFTA-certified labs to send samples, and talk with a nutritionist or extension agent to determine which tests to request. Once test results have been received, analyzing and interpreting results can be confusing at first. However, having results to compare will assist in knowing what to feed to certain groups of cattle and how to supplement. Schnakenberg said looking at the Dry Matter column, versus the As-Is or As Sampled column, will provide a better indication of actual content. Using the As-Is column is beneficial only to check moisture content.
Schnakenberg said. “For comparison, an RFV of 100 equals full bloom mature alfalfa. Good grasses typically will be lower than 100. RFV of below 80 won’t meet the energy requirements of most cattle.” Finally, nitrates could indicate toxic levels. Schnakenberg said labs only measure four primary components — moisture, ADF, NDF and nitrogen — from which other measurements are calculated such as RFV, TDN and net energy. Whether buying hay, selling hay or growing for your own use, using forage samples to determine hay quality is a valuable tool. Follow up with an agronomy specialist or nutritionist for help analyzing test results. The best hay will have high protein and low fiber, Schnakenberg said.
Protein, fiber, energy content, minerals, moisture, total digestible nutrients (TDN) nitrates and relative feed value (RFV) are commonly the most critical components. So, what do all the numbers mean? Schnakenberg said crude protein (nitrogen x 6.25) combined with fiber, TDN and RFV are useful tools that give a more accurate account of hay quality. Four percent is very mature, whereas 26 percent is very immature. By measuring crude protein (CP), carbohydrates and fat, TDN accounts for the amount of energy in a cow’s diet. “Leafy legumes have the highest TDN values,” Schnakenberg said. “Lactating beef cows need a TDN in the upper 50s. 12 percent CP + 58 TDN is good hay for beef.” Acid Detergent Fiber (ADF) is an estimate of woody fiber in forages. A lower ADF number indicates higher digestibility and energy levels and is often used for beef ration determination, Schnakenberg said. Good legumes will be 20s to mid-30s while good grasses will be low 30s to mid-40s. Neutral Detergent Fiber (NDF) is used as an indicator of intake by estimating total cell wall content. This number helps measure the intake of high-producing animals such as dairy cattle when determining rations. Schnakenberg said quality legumes typically measure in the high 30s to high 40s and grasses in the high 50s to 60s while not going more than 70 percent. RFV is an index based on digestible dry matter and dry matter intake based on ADF and NDF without CP factored in and is an overall indicator of forage quality, Schnakenberg said. Mark “RFV Requested” on the analysis form to get this information, which can be useful in hay sales. “Several (producers) buy hay based on a percentage of RFV on a per ton basis,” www.joplinstockyards.com
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