NIRS is a rapid and low cost computerized method used to analyze forage and grain crops for their nutritive value. Instead of using chemicals to determine protein, fiber, energy, and mineral content, NIRS uses near-infrared light.
3. In Vitro and In Vivo Disappearance Evaluation. These procedures are seldom used for farm forage analysis. They are however, commonly used by scientists to evaluate forage quality. Most often, dry matter disappearance in a specific period of time is measured and this value will indicate the digestibility of the forage.
a. In Vitro (in glass or in test tube)
In vitro is usually a two-step procedure. First the forage sample is digested using rumen fluid from a donor animal, to simulate digestion in the rumen. The sample is then digested in an enzyme solution to simulate digestion in the small intestine.
b. In Vivo (in animal)
The term "in situ" describes a procedure that involves placing small nylon bags containing forage samples into the rumen of live animals. This is done through a sealed external opening (fistula) into the rumen of an animal.
Steps to Putting up Quality Forages
The first principle in making good-quality hay for winter feeding is to harvest early. Rain damage will reduce hay yields and cause bleaching. However, rain does relatively little damage to hay quality as measured by forage digestibility, crude protein, and intake. Hay can provide a low-cost, homegrown winter feed. It can provide all the energy and protein needed by beef cattle and sheep. Even in rations for high producing dairy cattle, hay can provide over half the feed requirements. When we talk about forage quality, we want to know the hays digestible energy content, crude protein, and the potential dry matter intake of the forage as discussed above.
High levels of digestible energy in hay mean that a pound of feed will provide more energy for growth, milk production, or body maintenance. Digestible energy is measured as total digestible nutrients (TDN), or as net energy lactation (NEL), or as net energy maintenance (NEM) and net energy gain (NEG). Digestible energy is a measure of the solar energy captured by the plant which can be digested by the animal for use in maintenance and in making products useful to humans. In studies from central West Virginia, it was shown that as the harvest date for first-cut hay extends past early June, the digestibility of the hay decreases.
Crude protein is estimated by measuring hay's nitrogen content and multiplying that by 6.25. Much of the protein in feeds for ruminants (cattle, sheep, and goats) is broken down by rumen bacteria and used by them in digestion of carbohydrates (cellulose, sugars, and starches) in the forage and supplemental grains in the ration. This produces more bacteria which are digested in the true stomach of the animal. Once again, based on the WV data, as the date of harvesting first-cut hay extended past early June, crude protein content decreased.
Dry Matter Intake
When looking at animal performance on forage based diets 85 percent of the difference in performance is due to forage dry matter intake (DMI). One reason for this is that as forage digestibility increases forage DMI also increases. As more highly digestible forage is eaten, more energy is available to the animal for growth and milk production. Therefore, hay quality is best described as how much the animal can eat. Again, as the harvest date extends past early June the predicted DMI of the hay decreases.
Relative Feed Value
Relative Feed Value (RFV) is reported on many forage test reports. It is a combination of the forage's digestibility and DMI. Hay with an RFV of 115 will provide about 15 percent more digestible energy than a feed with an RFV of 100.
The Value of Legumes
Legumes are of major value in hay production. Legumes fix nitrogen from the air and eliminate the need to purchase expensive nitrogen fertilizers. In hay production, a good legume-grass stand having about 25 to 50 percent legume, will have a hay yield over the growing season comparable to grass fertilized with 150 lb. of actual nitrogen. With nitrogen fertilizers costing what they have, this can result in considerable savings per year.
Livestock will eat more legume forage than grass forage. This obviously allows the animal to grow faster or produce more milk. Also, mixed grass-legume hays are higher in crude protein at the same date than most straight grass hays. This allows for their use as a protein supplement with low-protein hays or for feeding with energy supplements such as corn.
Challenges to Making Hay Early
There are several challenges in making early-cut hay. The main one is that the drying conditions in late May are poor compared to late June. Fortunately, for beef cattle not all of our hay needs to be top quality. For them, however, the key is to make some hay early, to have some high quality forage for growing replacements, for cows after calving, and for use as a protein supplement to be fed with low quality late cut hay.
Be ready to make early-cut hay by having all equipment and storage preparations in place in early May. If the weather turns favorable you will be ready to go. Also, hay wrappers allow baleage to be made out of early-cut hay without drying it down as far as necessary as for hay. If you have a large herd, this can be a cost effective option. For smaller herds, renting the needed machinery is possible in some areas. Before deciding baleage, however, make sure to count all your costs, including disposal of the used plastic.
How much early-cut, high quality hay you need depends on your livestock management system and your goals. If your cattle are in poor body condition or are not breeding back as soon or as evenly as they should or if your supplemental feed costs are high, you should evaluate your system and see if you need to be managing your hay and forage program differently.
The foundation of your cattle operation is your forage program. Remember that your forages are the primary energy source for your herd. Cattle producers need to be as proficient in their management of forages as in their management of cattle. Development of a high quality forage program will dramatically reduce your production costs and improve operational profits.
Dr. Steve Blezinger is a nutrition and management consultant with an office in Sulphur Springs, TX. He can be reached at 667 CR 4711 Sulphur Springs, TX 75482, by phone at (903) 885-7992, or by e-mail at firstname.lastname@example.org. For more information please visit www.blnconsult.com.