Forage Testing is Key in Developing Economic Feeding and Supplementation Programs for Cattle

Hay, hay, everywhere, you can find it on every corner, but what is it worth.  I recently spoke about this with one of our Associate Professors and Texas A&M AgriLife Extension Service, Beef Cattle Specialist, Jason Banta about this very thing.  The following information should be very useful for all producers whether you raise your own hay for feed or you buy hay for feed.

Sometimes you have to spend a little money to make money applies perfectly to testing stored forages like hay and silage.  Sometimes “making money” actually means saving money when appropriate or spending money to ensure optimum production.

Hay quality can’t be determined from visual inspection. Often, hay that doesn’t look very good may actually test fairly well, and hay that looks excellent may test low.  Look at the hay to check for weeds, mold and foreign objects, but send a sample to the lab to determine quality.  If the quality of the hay is unknown, it is very easy to make costly feeding and supplementation decisions.

Forage testing is important to prevent supplementing more than is needed, to prevent reductions in performance below economic optimal levels and to ensure that each load or cutting of hay is fed to the groups of cows that can best utilize it.  Supplementing more than is needed can be very expensive. In some cases, especially for dry cows, hay alone may be sufficient to meet protein and energy needs. In other cases, feeding only 2 pounds of a 20 percent cube may be sufficient instead of feeding 3 or 4 pounds per day.

Just reducing supplement needed by 1 pound a day over a 100-day winter-feeding period can quickly pay for hay testing and generate substantial savings. For a 50-head cowherd, if 20 percent cubes cost $9.65 a sack, this reduction in supplement needed would save $965.

In other situations, money can be lost through reductions in performance. If hay is lower quality than anticipated and not enough supplement is fed to achieve or maintain desired body condition scores, then pregnancy rates will drop.

With the example of a 50-head cowherd, just increasing pregnancy rates by 2 percent or one calf would quickly pay for the money spent on hay testing. Additionally, while it will cost more to supplement the appropriate amount, the extra cost in supplement is much better than having drastically fewer calves to sell next year.  Many dismiss the need to test the hay they produce because they feel they are going to feed it all anyway. While all hay that is produced may be fed, it is economically important to utilize the hay in the most cost-effective manner possible.

Matching hay quality to animal requirements will result in lower supplement costs.  Additionally, if the quality of various hay cuttings is unknown and the better-quality hay is fed to the dry cows, it may be extremely difficult to supplement the lactating cows enough to make up for the remaining lower-quality hay.  Hay testing means different things to different people. Some just want to know what the protein content is. However, protein content has little correlation to energy content.

Hay that is rained on while in the windrow will usually increase in protein concentration because highly digestible soluble carbohydrates are washed out of the hay. To aid in developing an economical feeding and supplementation plan, hay must be sampled and analyzed appropriately. 

Each cutting or load of hay should be sampled and tested.  When sampling use a forage probe and collect samples from at least 10 percent of the bales in each load or cutting.  The samples can be combined so that only one composite is sent to the lab for each load or cutting.  

At minimum, forages should be analyzed to determine crude protein and to obtain a good estimate of total digestible nutrients (TDN) or energy.  Crude protein can be measured directly, and the procedures for doing this are fairly consistent across labs.  TDN, however, can’t be measured directly – and the methods for estimating the TDN of forages vary considerably from lab to lab.  Some labs do a very good job of estimating TDN, while others unfortunately do not. If you are working with a nutritionist, find out what labs they prefer to use before submitting samples.

Many nutritionists prefer labs that use a summative equation to estimate TDN where several chemical components of the forage are analyzed to estimate the digestibility and TDN content of four plant fractions.  These fractions include crude protein, neutral detergent fiber (NDF), non-fibrous carbohydrates and ether extract. The TDN values contributed from each fraction are summed to determine the TDN content of the forage. 

Neutral-detergent fiber (NDF) is generally the largest chemical fraction of most forages, typically ranging from 50 to 75 percent.  The digestibility of the NDF fraction can vary tremendously from forage to forage. Since it represents the largest fraction and thus largest TDN source of most forages, it is important to obtain a good estimate of NDF digestibility.  To accomplish this, several of the better-known labs offer in vitro analyses. In simple terms, the in vitro analysis involves collecting rumen fluid from a cow and incubating the forage sample in a jar with the rumen fluid to determine NDF digestibility.
Instead of using summative equations, many labs estimate TDN from regression equations that utilize acid-detergent fiber (ADF) or a combination of ADF and crude protein. While these equations work in some situations, other times they can greatly overestimate or underestimate the TDN content of a forage.