The Cow-Calf Manager

Livestock Update, December 2005

John B. Hall, Extension Animal Scientist, Beef, Virginia Tech

Feeding Whole Soybeans or Cottonseed to Beef Cows

Virginia is blessed with a variety of feeds and by-products that can be used by cattle. Feeding oilseeds such as whole soybeans or whole cottonseeds may offer some advantages to cattle during certain production stages. Ordinarily, the cost of whole cottonseed is too high to include them in diets for beef cattle, but soybeans are often cost effective. Although soybean prices are high this year, producers often have several bushels that are left over from marketing tractor trailer loads. Alternatively, some beans are rejected at the elevator for low test weight or other defects. These "leftover" soybeans create an opportunity for feeding cattle. Recently, whole cottonseed prices have become competitive as well.

Feeding Considerations
Ruminants (cattle, sheep, goats) were designed to efficiently digest large amount of fibrous feeds. The rumen microbes that do the most of the digestion cannot handle large amounts of fat. Ordinarily, cattle diets contain about 2 % crude fat in the entire diet. Diets which exceed 8 % crude fat often result in decreased digestibility of fiber and rumen upset. Therefore, it is recommended that diets do not exceed 5% crude fat.

Oilseeds contain 20% to 30% crude fat. If the base diet contains 1.5% to 2.0% crude fat then oilseeds should not be fed in excess of 0.5% of body weight. For stocker cattle, the upper limit of oilseed supplementation should be approximately 3 lbs per head per day. Mature cows can be fed up to 6 lbs of whole soybeans.

Don't whole soybeans need to be roasted before feeding? No! Raw soybeans contain a trypsin inhibitor that impairs protein digestion and amino acid absorption in non-ruminants. Roasting soybeans inactivates this enzyme inhibitor which is essential before feeding whole soybeans to non-ruminants. Ruminants are not as sensitive to this enzyme inhibitor especially at the level whole soybeans can be fed to ruminants. So, whole soybeans do not have to be roasted before feeding to cattle.

Soybeans also contain phytoestrogens. These plant estrogens can act like the estrogen normally produced in female mammals. In high doses, these phytoestrogens may impair reproduction. It is recommended that high levels of soybeans not be fed to replacement heifers within 2 months of breeding.

Results in cattle performance by feeding whole cottonseed or whole soybeans
Feeding whole cottonseed or whole soybeans to cows in late gestation has been shown to increase subsequent pregnancy rates. The effect was greatest when cows were in low body condition during late gestation or forage availability after calving was limited. In addition, cows fed oil seeds during late gestation produced calves that were better able to withstand chilling and cold conditions.

Primiparous cows appear to derive the most benefit from feeding additional fat. Several studies indicate increased pregnancy rates of 13 to 15 %. This increase is primarily due to more high-fat fed heifers cycling early in the breeding season, which in turn means greater first service conception rates. In addition, calves from these heifers are 15 to 30 lbs. heavier at weaning. First calf heifers in poor body condition can also benefit from the positive effects of increased dietary fat. Low body condition heifers (< BCS 5) often do not respond as well to additional energy from starch sources as expected. Low BCS heifers on high-fat diets (cracked safflower seeds or whole soybeans) receiving the same energy as controls had dramatic increases in the percentage of heifers cycling by the beginning of the breeding season (Figure 1).

The research on developing heifers is less extensive than studies on postpartum cows and heifers. Lammoglia and co-workers (2000) reported a high-fat diet increased pregnancy rates and cyclicity in heifers of a double muscled breed, but it had little effect or a negative effect in other breeds. In contrast, we have preliminary data that indicates an advantage to feeding whole cottonseed (5 % fat diet) to developing beef heifers (Figure 2). The difference between the two studies may be related to the length of time the high fat diet was fed before breeding. Our heifers were fed the high fat diet for 75 days before breeding compared to 162 in the other study. In another study, we compared supplementing developing heifers on stockpiled fescue with either high starch (corn), high fiber (soyhulls), or high fat (whole cottonseed). Growth and pregnancy rates were not different regardless of type of supplement. We are continuing further research to determine if short-term feeding of high fat diets, perhaps during synchronization, will improve reproduction in heifers.

Recommendations for feeding whole soybeans or cottonseed
Whole cottonseed or soybeans can be included in beef cow or heifer diets at a maximum amount of 0.5% of body weight per animal per day (ie. 6 lbs for cows and 3 lbs for heifers). Beef producers should consider including whole cottonseed or soybeans for:

1. Cows are thin during late gestation
2. 1st calf heifers
3. Replacement heifers
4. Supplement to extremely poor quality hay

Cost should also be a consideration for inclusion of whole cottonseed and whole soybeans into cattle diets. Since research indicates that including whole cottonseed or whole soybeans may be helpful only in certain situations then producers should not pay extremely high prices for these commodities. In general, if the price of whole soybeans or whole cottonseed is similar to other commodity feeds such as corn gluten feed or soyhulls then soybeans or cottonseed will be economical to use in cow or heifer diets.

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