Whether purchased or put up yourself, the importance of forage analysis cannot be overstated. A producer may feel really confident their hay is “high” quality, but there is really only one way to be sure the herd is getting sufficient fuel for their stage of production: Test it.
If hay is the main forage during breeding season, and protein and energy are just a little off, there will be cows calving three weeks later the following year. The result could be a 50-pounds-lighter calf at weaning. However, with a forage analysis in hand, producers can know how much of a gap might exist and plan accordingly. The “UGA Basic Balancer” developed by Dr. Lawton Stewart can be found online to help assist in ration planning.
After calving, a cow’s nutritional requirements will obviously increase. Assuming a body condition score (BCS) of 5 for cows and 6 for heifers, visualize that they will lose roughly a body condition score (80 to 100 pounds of energy reserves) even with ideal nutrition. From calving to peak lactation, which is about 50 days, nutritional requirements will increase quickly. Peak lactation requirements are 12% crude protein (CP) and 60% TDN (energy).
Cows in late lactation should be bred but still require 9% to 10% CP and 55% TDN. Even the dry cow should be monitored for body condition, particularly during the cold snaps to come. The dry cow is still pregnant and needs to provide essential nutrients to the calf in utero. This group of cows still need at least 7% crude protein and 50% TDN on a dry matter basis. Please note, this is right after drying off, and the nutritional requirements will gradually increase until calving.
An additional benefit of forage testing is knowing potential nitrate levels. When levels are nearing 8,000 parts per million (ppm) or higher, serious planning needs to take place to minimize impact and death loss in the herd. Cattle turned directly onto forages that have a dramatic difference in nitrate levels can die rather quickly. A forage analysis may save your cows and your calf crops. 
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Jason Duggin
- Beef Extension Specialist
- University of Georgia
- Email Jason Duggin
