Forage for grazing, hay, baleage or silage production is critical for cow-calf operations. Lack of abundant, high-quality forage is often the major reason for lower-than-desired calf performance and slower gains in replacement heifers. Producing quality forage and hay is also important to reduce or eliminate energy and protein supplementation for the cow herd.
Managing stocking rates and stubble height is key to optimize forage yields. Overgrazing leads to less forage yield, a less robust root system, and higher levels of supplementation are required to maintain cow body condition.
When making hay, it is a balance between quality and yield. Assuming growing conditions are good, forage yield will increase each day to a point. However, as forage yield increases, forage quality generally decreases.
The number of hay harvests during the year and the time between cutting will vary depending on forage species, rainfall and geographic location. A perennial forage like bermudagrass may be harvested three to five times a year with three to five weeks between cuttings. In contrast, hay produced from an annual forage like sorghum-sudangrass might only be harvested once or twice per year.
Hay quality – TDN (total digestible nutrients) or CP (crude protein) – is influenced by several factors including species, variety, maturity, temperature, nitrogen fertilizer and rain after cutting but before baling. As a general rule, hay produced from annual forages will be higher in TDN than hay produced from perennial forages. Hay from cool-season forages will be higher in TDN than hay produced from warm-season forages. As forage matures, both TDN and CP content will decline. Managing forage maturity by harvesting sooner provides a significant opportunity to increase forage TDN content. Delaying harvest by just a week can result in a 3- to 4-point decline in TDN content.
Temperature has a significant impact on forage digestibility and thus TDN content. As temperatures increase, more lignin is deposited in perennial forages, causing a reduction in digestibility. For the southern part of the U.S., forages grown in the spring or fall will be higher in TDN content than those grown in the summer.
Nitrogen fertilizer will increase CP content of the forage. It can also substantially increase yield if other nutrients are adequate.
If hay gets rained on after cutting but before baling, it will cause a decrease in TDN content because highly digestible carbohydrates will be washed out of the hay.
