A forage nutrient analysis is an underutilized tool. Nutrient content determines forage value. In addition, forage dry matter content influences livestock feed amounts required per day and ability to properly preserve forages for winter feeding.
Consider the calculations values below for a second cutting grass hay (harvested in late June), a first cutting grass baleage (harvested in late May), and a first cutting perennial warm season grass hay (harvested in mid-July). (See chart.)
The above evaluation of dry matter need does not take into consideration rumen fiber fill. It should be noted that cattle DM intake is limited to a maximum of 1.5 % of their body weight in Neutral Detergent Fiber (NDF) for high quality forages.
For a 1300-pound cow X .015 max NDF = 19.5 pounds of NDF is her max consumption. In our example, our cow will need to consume 31.4 pounds DM X .618 % NDF content of the baleage = 19.4 pounds of NDF consumed; this is her limit.
Forages with a greater than 60% NDF content on a Dry Matter basis may limit a cow’s ability to consume enough nutrients from the forage alone. If the forage quality is low they may need additional energy and protein.
Evaluating protein and energy
Our hay and baleage provides enough protein as a percentage of forage DM for all stages of cattle production. Our warm season grass, however, is right at the NRC (National Research Council) requirements for heavily lactating cows and for light calves.
Our hay and baleage will be short on Total Digestible Nutrients (TDN) which may cause cows to lose weight during lactation. In addition, young calves may not gain to their potential. Pregnant yearling heifers will also have a difficult time meeting their energy needs on this baleage and dry hay.
Our warm season grass is adequate in TDN content for dry mature cows in the middle and last third of pregnancy, but lacking in energy for all other stages of cattle production.
Summarizing
Forages can provide most of the major nutrients ruminant livestock need depending on their quality. What forages lack most frequently is energy.
If energy levels being supplied in forages are marginal they will be inadequate in January and February when cattle deal with extreme cold. For example, at 10 degrees and with wind chill, a cow’s energy requirement may increase by more than 20 percent and will be further aggravated in wet muddy conditions.
Forages will also lack in salt, and trace minerals, which can easily be provided with a loose free choice trace mineral. Vitamin A should also be provided during the winter months.
The question is, how does your hay stack up? Do you expect your cattle to lose weight? If you had to compare the value of hay, doesn’t it make sense to evaluate forage nutrient content?
The cost of poor body condition at calving can be expensive. The time to improve cattle body condition is during periods of low stress, not at calving, breeding season or January and February.
Your local OSU Extension office can help you find a lab that can analyze forage. Utilize this valuable tool because the cost of not knowing forage quality is far too expensive.
