02/12/1997

Cottonseed Hulls Provide New Feed Options for Dairy Producers

AUBURN, Ala. - Cottonseed hulls, byproducts of the South's thriving cotton industry, may provide an affordable feed option for dairy producers, according to Shaochen Gu, a graduate research assistant in Auburn University's Department of Animal and Dairy Sciences (ADS). Gu has been evaluating the use of cottonseed hulls as a source of roughage in total mixed rations as a replacement for hay and corn silage.

Though hay and corn silage are typically used as roughage in dairy cattle rations, these sources are often difficult to obtain, expensive or of questionable quality. Cottonseed hulls, however, are abundant and affordable in the South and often already are used as a feed for beef cattle. Use in the dairy industry has been limited because more information was needed on the proper use of cottonseed hulls in dairy diets. Gu explained that dairy cattle producers must carefully balance the nutrients in their cows' rations to ensure that milk production is not adversely affected. Minor changes in a cow's diet can affect both quantity and quality of milk produced.

"Protein sources are of interest in dairy cattle diets because milk yield may increase if cows are fed certain feed combinations," said Gu. "Best results are often obtained with protein sources that are partially digested in the rumen, then fully digested in the lower gastrointestinal tract."

Proteins that are digested mainly in the rumen are referred to as low undegradable intake proteins (UIP). Proteins digested partly in the rumen and more fully in the lower intestinal tract are called high UIP.

Research has shown that the type of roughage fed to dairy cattle can affect the use of protein by a cow. Gu and other ADS researchers conducted two studies to see if cottonseed hulls would affect the nutrient value of low and high undegradable intake proteins (UIP), and ultimately affect milk production and quality. The studies were conducted at the E.V. Smith Research Center Dairy Unit in Shorter, the main research station for the Alabama Agricultural Experiment Station.

In the first study, 72 Holstein cows in early lactation were fed four rations using different forage sources: corn silage only or 90 percent corn silage plus 10 percent of cottonseed hulls, coastal bermudagrass hay or alfalfa hay. All rations were adjusted to provide equal levels of protein, energy and mineral requirements. Soybean meal (as a low UIP supplement) or a combination of soybean meal, bloodmeal and feather meal (as a high UIP supplement) were used for protein sources in the rations.

Results of this study showed that cows on the cottonseed hull rations ate more feed than those on the other three roughage sources. In addition, the cows that ate cottonseed hulls with the high UIP supplement produced more milk than cows on any of the other rations.

A second study then was conducted to see if varying levels of cottonseed hull in high and low UIP diets made a difference in milk production. This study evaluated rations with 10 percent cottonseed hull and 36-38 percent corn silage, 20 percent cottonseed hull and 16-19 percent corn silage or 30 percent cottonseed hull and no corn silage. Cows in each forage source group were fed either high or low UIP sources from the same sources as the previous study. All rations were adjusted to meet equal levels of protein, energy and mineral contents.

Results of this study showed that, as the amount of cottonseed hulls in the diet increased, dry matter intake also increased, though milk production did not increase. Interestingly, cows on the high UIP rations ate less feed than those on the low UIP diets, but produced more milk than those on the low UIP diets.

Based on these results, Gu said that cottonseed hulls are a viable option for dairy producers if close attention is paid to protein sources and balancing rations. These findings may be helpful for dairy producers as well as the cotton industry.

-30-

News from:

Office of Ag Communications & Marketing

Auburn University College of Agriculture
Alabama Agricultural Experiment Station
3 Comer Hall, Auburn University
Auburn, AL 36849
334-844-4877 (PHONE) 334-844-5892 (FAX)

Contact Jamie Creamer, 334-844-2783 or jcreamer@auburn.edu
Contact Katie Jackson, 334-844-5886 or smithcl@auburn.edu

02/12/97