By Jace Scott
As supplementation costs continue to rise in Nebraska, producers are looking for economical ways to meet protein and energy requirements of their cattle. Hay produced on irrigated grass and subirrigated meadows can be a potential supplementation source throughout the state.
Crude protein typically ranges between 6% and 13% dry matter basis with energy (total digestible nutrients) ranging between 50% and 65% on a dry matter basis. That's a wide spectrum. The side of the spectrum that your hay falls under can be influenced by management inputs and timing of harvest.
Many native meadows tend to be dominated by cool-season grasses. As a result, nutritive values tend to be highest in early summer (June). However, many producers don't harvest until early or mid-July, either because subirrigated meadows still are too wet to access, or because they are trying to capture increased biomass.
While both arguments are valid, if environmental conditions permit, June harvest should be considered if improved hay quality is the main objective. Although seemingly insignificant in terms of time, the weeks between the end of June and early July see a dramatic drop in quality of forages. Cool-season grasses are beginning to mature, elongate and put up lower quality stems and seed heads.
In a small study conducted at the University of Nebraska’s Barta Brothers Ranch, I measured meadow hay quality and quantity over the course of a growing season. In mid-June, average CP of meadow grass was about 9%, and by mid-July, it had fallen to 6.5%.
The change in June TDN to July TDN was less dramatic as it fell from 62% to 61%. However, by August, average TDN had fallen to 56%. Data collected at the University of Nebraska’s Gudmundsen Sandhills Laboratory also indicate a similar trend in decreasing quality as the hay season progresses.
An earlier June harvest also presents an opportunity to utilize more meadow regrowth. In the Barta study, quality of regrowth was measured in mid-September. Because of cooler late summer temperatures in 2018 and the dominance of cool season vegetation, quality in mid-September rose to 8% CP and 58% TDN. Because of previous harvest, regrowth of vegetation is predominately leafy material instead of stem, which improves overall palatability.
Although quality is more affected by time of harvest, fertilizer application to meadows is a method to increase hay yield and potentially improve quality. In the Barta study, fertilizer applied at rates of 80 pounds per acre nitrogen and 40 pounds per acre phosphorus (80N 40P), 40 pounds per acre nitrogen and 40 pounds per acre phosphorus (40N 40P), 40 pounds per acre nitrogen (40N), as well as unfertilized control plots were compared over the course of the growing season. The higher fertilizer rate of 80N 40P on average produced nearly 1,000 pounds per acre more forage compared to control plots and nearly 200 pounds per acre more forage to the next closest fertilizer treatment.
The most effective fertilizer treatments in terms of improving quality were the applications of 80N 40P and 40N. The 80N 40P treatment resulted in an average CP and TDN content of 7.3% and 58.5%, respectively, over the course of the season, compared with 5.6% and 58% in the control. The 40N treatment resulted in an average CP and TDN content of 7.1% and 60%, respectively, over the course of the season, compared with 5.6% and 58% in the control. However, the quality of 40N regrowth was less than the higher application rates of fertilizer as well as the control.
Economically speaking, 40N per acre was the most attractive in terms of CP gained in forage compared with the control based on central Nebraska spring fertilizer costs. It cost $12.14 for each additional percentage of CP gained over the control for the 40N fertilizer treatment per acre. The most expensive was the 40N 40P treatment costing $41.25, with the 80N 40P being slightly less at $36.25. Costs for each additional pound of forage produced per acre were comparable between treatments, ranging between $0.04 and $0.07 for each additional pound over the control.
Is fertilizing an economical way to help meet nutrient requirements of cattle? It depends on the year and variations in costs. Haying operation costs, alternative forage production costs, fertilizer costs and alternative purchased feed source costs constantly change and will need to be examined on a regular basis.
Fertilizer’s greatest value is increasing yield, while timing of harvest seems to have the greatest influence on quality. A good option is to use both. Optimize quality by earlier harvest, offset yield losses through fertilization and capture quality, palatable late-season regrowth. Also, use hay probes to test the quality of your hay as it may change from year to year and pasture to pasture.
Scott is a Nebraska Extension educator.
This report comes from UNL BeefWatch.