Frequent rain has delayed first cutting hay harvest this spring. Unfortunately, delayed hay harvest has a direct negative impact on the value of forages. So how did the forage change?
In early June we sampled fescue pasture at Ohio State University Eastern Agriculture Research Station in Belle Valley, we again sampled that same field and forage fourteen days later.
These results indicate a significant reduction in forage quality within a relatively short period of time. As we delay harvesting of forages they mature and become less digestible. ADF is a measure of cellulose and lignin.
As the amount of ADF in the forage increases with plant maturity, digestibility decreases. NDF is determined from the amount of cellulose, lignin, and hemicellulose in the forage which is found in the cell wall of plants. As the NDF values increase, plant materials become indigestible and cows will consume less dry matter.
As a rule of thumb, the maximum NDF dry matter content of the daily ration should be from 1.2 to 1.5 percent of the cow’s body weight. For this reason, NDF values can be used to estimate forage intake. As NDF values increase, forage intake will decrease. Crude protein content dropped 5.3 percentage points in a fourteen day period. RFV is a forage quality index used to compare hays within a similar classification such as alfalfa, grass, or mixed.
Since grasses have a higher fiber digestibility than legumes, this index should not be utilized to compare legume hay say to grass hay. In our samples, RFV dropped as the calculation is based on ADF and NDF forage content and as these rise forage value declines. Each farm will have varying forage values and we must ask ourselves what is the best use of the forage we have.
Generally, we try to feed according to changing animal nutritional needs. In this case the later harvested forage cannot meet the nutritional needs of a beef cow through much of the year.
However, a mature, dry, mid-gestation cow in good body condition fed this poorer quality hay in late summer would be an option and would provide us a means to stockpile forage. It would be a mistake to attempt to feed this hay with no supplementation to a cow in the dead of winter, when she is near the end of her pregnancy and if she is in poor body condition.
Plan hay feeding according to forage nutritional value and animal needs. For more information on testing forage or laboratories near you contact your local OSU Agriculture Extension Educator.