Feeding Whole Cottonseed to Dairy Cows and Replacements*

Whole cottonseed has become a very popular feed for dairy cows. It can be fed just as it comes from the gin without processing. While cottonseed is higher in cost than normal, it is still a wise buy for dairy cows. Here are some factors to consider to determine safe levels of whole cottonseed that can be fed. Some of these are gossypol, high fat content, and the potential for aflatoxin. Whole cottonseed should be clean, dry and stored in a dry place. If long term storage is being considered it should not be stacked too high so as to prevent heating and or moisture build-up.

The primary factor that limits the amount that may be fed is gossypol. Gossypol is a yellow polyphenolic pigment found in the cotton plant and in the small pigment glands in the seed. During processing, some of the glands are ruptured and the gossypol released. It may become bound with various compounds of the seed. The remaining gossypol termed "free" gossypol is harmful when fed at high levels. Research has not definitely determined if both bound and free gossypol have an effect in the animal.

While many dairy cows have been fed up to 10 pounds of whole cottonseed per day without any adverse problems, it has been known for many years that gossypol was harmful to monogastrics such as chickens, swine and young ruminants. Until recently mature ruminants were thought not to be affected by gossypol. In 1975 gossypol toxicity developed (in a 700- cow dairy herd in Alabama) when large amounts of cottonseed meal was fed as the single source of protein to achieve high levels of milk production. Approximately 25 head of mature cows exhibited classical gossypol toxicity symptoms and died. These symptoms were depression, loss of appetite, anorexia, labored breathing and red blood cell fragility. In a later controlled study at Auburn University, these same symptoms were demonstrated when cows were consuming an average of 24 grams of free gossypol per cow per day. Also, the livers of cows at the end of the study contained free, bound and total gossypol levels in relationship to the level of intake. Unfortunately, there have been no other studies with lactating cows to determine the precise level of gossypol that can be safely fed. The 24 grams per cow per day calculate out to approximately 18 mg of gossypol/lb of body wt/day or approximately 0.1 percent gossypol in the total dry matter.

How to Determine Safe Levels to Feed

Table 1. Gossypol Levels in Selected Cottonseed Products (Martin)

Feedstuffs, August, 1990

Table 1 adapted from an article in Feedstuffs, August 6, 1990 shows the ranges in gossypol content of various cottonseed products.

Using the information in Table 1 and the limited research information that indicate that 0.1% or 18 mg per pound of live animal weight is the maximum that can be fed, one can begin to estimate an amount that might be fed safely. Since the 0.1% caused deaths, certainly this amount should not be fed. Based on field experience, 6 pounds of whole cottonseed has been successfully fed for fairly long periods of time and up to 10 pounds have been fed for sort periods without apparent harm. Using the information in Table 1 for whole cottonseed let's assume that there is 0.5% free gossypol present and 6 or 8 pounds are being fed. How much free gossypol are cows consuming?

The calculations are:

Assume the cows are consuming 45 pounds of dry matter. Then the ration contains 0.067% gossypol:

For a group consuming 8 pounds of whole cottonseed, the calculations are:

Another way of calculating this is to calculate the grams of gossypol intake. This is done by multiplying 454 grams x pounds of gossypol. For the above example, 6 pounds of whole cottonseed contains 0.03 pounds of gossypol or 13.62 grams (454 x 0.03 = 13.62) and 8 pounds yields 0.04 pounds or 18.16 grams (454 x 0.04 = 18.16) of gossypol. Similar calculations can be made for various combinations of cottonseed products by calculating the amount of gossypol contributed by each source and adding the amount contributed by each source.

An example of this is illustrated as follows:

The dairyman is feeding 3 pounds of whole cottonseed and 6 pounds of direct solvent extracted meal that contains 0.3% free gossypol.

(6 lbs X 0.3) / 100 = 0.018 lbs gossypol

0.015 + 0.018 = 0.033 lbs

0.033 x 464 = 15 grams.

Again based on the limited data, we would expect that 15 grams of free gossypol to be an upper limit for safe feeding. This may not be a safe level for long term feeding during summer when respiratory stress is extremely high.

How to Feed Young Stock?

Again, limited research data indicate that young ruminants may safely be fed 5 to 10 mgs per pound of live weight of gossypol. Suggested upper limits for various size replacements are shown in Table 2 using 10 mg/lb of live weight or 1 gram/100 lbs of body weight.

Table 2. Suggested maximum gossypol and whole cottonseed levels for Replacement Dairy Heifers and Cows.

Whole cottonseed is an excellent feed and should be used extensively whenever practical. It is an excellent source of protein (20%) crude fiber (22%) and TDN (87%). However, its fat content (18%) also should limit its feeding to about 7.0 pounds per cow per day. Seven pounds of whole cottonseed will yield approximately 1.0 pounds of fat which is about the maximum recommended from oilseeds.

Sometimes cottonseed that has not been dried properly or has been handled improperly in storage may mold and contain aflatoxin. Make sure the whole cottonseed you purchase is free of cockleburs and other noxious weed seeds. Know your supplier and pay attention to what you are receiving and how you handle it after delivery. Finally, don't overfeed it because it is a good buy. Good things can be overdone!