|Rice Straw Utilization by
Project Leader and Principal UC Investigators
Glenn Nader, livestock farm advisor, UC Cooperative Extension Butte/Sutter/Yuba Counties
Rice straw is a major feed resource in
many developing countries that is now getting considerable attention in California due to
disposal problems. This research, in its third year, examined the intake, gain and health
performance of bred cows fed rice straw silage on a commercial beef ranch in Northern
California. In addition, variation in the nutritional value of different rice varieties
and rates of nitrogen fertilizer were studied.
Haylage is about 60 percent moisture; most straw bales range from 12 to 16 percent moisture. The cost of producing the 900 round bales used in this research averaged $10 per bale roadside. Most field reports put the cost of large standard baled straw at $25 per ton roadside. A comparison of the two showed that haylage costs are higher than traditional large bales, but increases in forage value and palatability may make the investment of haylage equipment worth it. Cattle weight gain data being analyzed will need to bear this out.
Grazing rice straw
In late September 2000 beef cattle at various stages of lactation and pregnancy were grazed on a stripper-harvested rice field to determine whether this might be a cheaper form of removal than incorporation. The straw was sprayed with a molasses/urea mix to increase palatability and digestion. Nutrient value of the rice straw was 4.6 percent protein and 50.2 percent acid detergent fiber.
Two weeks into the study the cows began to lose weight. Furthermore, the molasses/urea mix had either washed off in the rain or volatilized, so a liquid supplement trough was brought in. This seemed to return the cows to normal. After 43 days the cows were removed because of the rice producer's concern about soil compaction.
Field studies have revealed a large degree of variation in the nutritional quality of rice straw. Prior research has shown that straw from the Japanese rice variety Akitakomachi was the best to use for livestock feed. An examination of eight California public varieties sought to quantify differences of protein content and digestibility, the two most important nutritional considerations in the use of rice straw for livestock feed.
Calihikari and L-204 contained about a half-percent higher protein levels than other varieties in this analysis. Other feeds would still be required to balance protein requirements. Calmati 201 rated lowest on acid detergent fiber. The analysis is continuing to determine whether different maturity stages at harvest may influence forage values of each variety.
Two fertility management studies were conducted on Akitakomachi at six rates. Grain and straw protein showed a direct and significant response to applied nitrogen. Split applications were more efficient in the conversion of nitrogen to straw protein. However, digestibility decreased as nitrogen rates increased.
This study also examined nitrogen fertility management for eight different varieties and observed increasing protein percentage from a low of 3.37 percent with a 50 pound application to a high of 5.74 percent at 200 pounds.