Hay represents a major component of most winter feeding programs for cow-calf producers. To develop a successful, cost-effective supplementation program, it is critical to test hay. If hay quality is good enough, supplementation may not be needed.
Each cutting or load of hay should be tested. A hay probe should be used to pull core samples from about 10% of round or large square bales. The core samples from each cutting or load should be combined into one sample that is sent to the lab for analysis. Hay probes come in both push-type and drill-type designs, and the best option might vary depending on a person’s age, physical capabilities, etc. Most producers find that a quality push-type probe is much quicker and more enjoyable to use than drill-type probes.
If possible, it is best to let hay cure for at least six to eight weeks before collecting samples. For many producers, it works well to just sample most cuttings, if not all cuttings, at one time in early fall.
Unfortunately, not all testing labs are the same. Before sending in hay samples, it is critical to visit with a ruminant nutritionist to get a recommendation on what lab to use and what tests are most appropriate for the samples being analyzed. Don’t assume a lab can provide the right information just because of its name.
A good hay test should provide information on the energy (e.g., TDN = total digestible nutrients) and protein content of hay. The TDN content of hay should be estimated using a summative equation that accounts for:
- Protein
- Neutral detergent fiber (NDF)
- Starch
- Water-soluble carbohydrates
- Fatty acids
- Ash
These analytic fractions are routinely measured by progressive forage labs. The NDF fraction of hay provides the greatest source of energy, and an estimate of NDF digestibility is a critical component of a good hay test. NDF digestibility will vary tremendously depending on growing conditions and forage species.
When measuring protein, the lab should report crude protein, adjusted crude protein, ruminal-degradable protein and ruminal-undegradable protein. In most cases, the crude protein value and adjusted crude protein value will be the same. If the adjusted crude protein value is lower, it indicates the hay was baled too wet and went through additional heating that reduced the protein and energy content of the hay.
