Defining Forage Variability
in Rice Straw - 2006

 

 

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Project Leader and Principal  Investigators

Glenn Nader, livestock farm advisor, UC Cooperative Extension; Sutter, Yuba, Butte counties

This project continues its examination of how to utilize rice straw as a forage supplement in livestock feed.  Rice straw differs from wheat or barley straw.  Researchers believe its digestibility can be improved through physical or chemical alteration. The focus of 2006 work was physical field treatments to improve digestibility, consistency and utility of rice straw. Research also examined rice straw use in dairy heifer replacement rations.

Macerator studies

In 2004 researchers obtained a commercial field macerator, a machine that mechanically treats straw to make it dry faster and alter more of the plant surface physical character.  The design of the macerator was modified in 2005 to increase the physical impact by doubling the surface area of the steel rollers.

Field experiments in 2005 included eight groups of 10 steers each. Four randomly selected groups were fed macerated rice straw; the other four were given unmacerated straw. The feed mix was 60 percent alfalfa, rice bran, and cottonseed, and 40 percent rice hay. Animals were fed by 8 a.m. and allowed to consume all the feed before being given rice hay. The trial ran from October through December. 

Laboratory analysis showed that maceration lowered acid detergent fiber, which should have improved digestibility. There were also other significant differences in the macerated rations – higher soluble crude protein and lower fecal neutral detergent fiber. Nonetheless, no change in animal performance was observed. Based on these results, researchers have concluded that the maceration process is not providing enough physical alteration of rice to change animal performance.

Harvesters examined

In 2006 the physical condition of rice straw forage from a rotary harvester was compared with straw from a “straw walker” designed harvester. Combined with flail chopping, the rotary harvester provided the optimum physical alteration of forage. These treatments are undergoing laboratory analysis.

Eight groups of 10 steers each were fed treated rice straw; the other four were given untreated straw. A dairy heifer ration of  70 percent alfalfa, rice bran, rolled corn and whole cottonseed, and 30 percent rice hay. Animals were fed by 8 a.m. and allowed to consume all the feed before being given rice hay. The trial ran from October through January 2007.

Researchers are focusing now on the chemical changes during drying and their impact on digestibility.  Encouraging initial results from the study are that with a 30 percent rice straw diet, the animals gained more than two pounds a day.  Dairy heifer gain targets are generally 1.5 to 2 pounds per day.

Dairy demonstration

The project leader initiated a demonstration project for rice hay use with two commercial dairies. This project is experimenting with different types of ration mixers to determine which method – horizontal or vertical – provides the most consistent nutritional quality. The horizontal mixer typical of dairy operations in the Central Valley afforded more time savings and experienced fewer mechanical problems. The dairy owner and a nutritionist are evaluating the results of these two different methods.

Digestibility probed

A study is also under way to improve the chemical qualities of rice hay forage in collaboration with the USDA Agricultural Research Service in Albany, Calif. The project leader is working with Dr. Kevin Holtman to study the chemical properties of rice hay that may be causing changes in digestibility that occurs during drying.

Extension outreach

To extend information about the use of rice hay in dairy heifer rations, the author prepared an article for California Dairy magazine.

The project leader also published a peer-reviewed article listed below on the effect of manganese in rice straw on beef cattle. This research showed that high levels of manganese did not compromise animal health by adversely affecting the status of other nutritional minerals.

A rice hay education meeting was held for rice producers and hay brokers in Maxwell during June 2006.

 

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