Managing production, feeding of hay
By Daren Redfearn
Oklahoma State University
In some areas, there has been ample rainfall to produce a substantial amount of forage and hay as compared with the past few years. This includes wheat hay and wheat straw and other winter grasses such as tall fescue and annual ryegrass.
Likewise, production of summer grass hay and pastures, including bermudagrass and native grasses, increased dramatically this year. There were also numerous acres of summer annual forages planted, so hay production from these has been quite common. Recently, johnsongrass growth has increased rapidly in many hay fields and pastures and much of this was also baled. Much of the hay produced will likely have varying quality. It is possible that some hay has high quality and some hay that would have had high forage quality, but it was rained on during the curing process. Finally, there will be some hay available that is low quality due to it being overly mature as a result of delayed hay harvest schedule. Even though hay production has increased, much of this forage production is best classified as mixed hay. This is because of the fluctuations in temperatures this past spring and extended cooler, wetter weather that persisted into May.
Across much of the region, there were many cool-season annual grassy weeds that took advantage of these growing conditions. There are numerous reports of these also invading summer grass hay fields and pastures. If these are present in the first cuttings of summer grass hay, the forage quality will lower. In later cuttings, these should not present any problems. It is also likely that there could be broadleaf weeds present unless they were controlled prior to harvest. Is it better to purchase and feed a low-quality hay or high-quality hay? To answer this question, we need two key pieces of information.
The easiest piece of information to obtain is the animal nutritional needs. Nutrient requirements are not consistent for all classes of livestock, so we need some knowledge of their body weight and stage of production. For more information on nutrient requirements of beef cattle, please see OSU Extension Circular 974 (Nutrient Requirements of Beef Cattle), available at http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document- 1921/E-974web.pdf.
The second piece of information is the results from a forage analysis. At a minimum, it is important to know the crude protein and total digestible nutrient values for hay supplies. During the winter hay feeding period, a general rule of thumb is that it will take about 1,000 pounds of hay to feed a mature cow for 30 days (33 pounds of hay per day), assuming none is wasted. The following example can be used to help explain the relationship between forage quality and stage of production. In a 1,000-pound bale of bermudagrass hay with 5 percent CP and 45 percent TDN, there are 50 pounds of CP and 450 pounds of TDN. An 1,100-pound mature cow in the middle third of pregnancy requires 1.4 pounds of CP and 9.7 pounds of TDN each day. From a couple of simple calculations, we can determine that the CP requirement for this animal is 42 pounds and the TDN requirement is 291 pounds for 30 days. We can quickly determine that this hay should be adequate to maintain the 1,100-pound mature cow in the middle third of pregnancy if her daily hay consumption is at least 28 pounds.
The nutrient requirements for this same 1,100-pound cow the first 90 days after calving require 2.9 pounds of CP and 16.8 pounds of TDN each day. Our quick calculations show this hay is now deficient in both protein and energy for this animal in a different stage of production. Assuming she consumes 33 pounds of hay per day, both her protein and energy requirements will be deficient. Generally, it is difficult to make animals consume more than about 33 pounds per day of low-quality hay. In this instance, both additional protein and energy should be provided to meet the nutritional requirements.
To summarize the key points, it is important to know the quantity of nutrients being supplied and the nutrient requirements of the animal. Then supplement any deficiencies that exist. It would require about 6 pounds of a 20 percent CP supplement to meet the 37-pound CP deficiency of an animal during the first 90 days after calving if she were consuming bermudagrass hay containing 5 percent CP and 45 percent TDN. However, this amount of supplement would also meet the TDN deficiency. At a cost of $250 per ton for the supplement, the cost of supplementation of an animal during the middle 1/3 of gestation would cost $16.20 per cow per month. In this example, over-supplementing a 50-cow herd for 90 days during the middle third of gestation would result in unnecessary feed cost of $3,375. Most forage quality analyses cost $10 to $20 per sample. It is difficult to assign an economic advantage to forage quality testing. However, the cost to determine if additional protein or energy feeding is needed would be recovered in feed cost savings or improved animal performance. Greater profit potential is the primary reason livestock producers need to know the quality of the forages they are feeding.