Document Type : Research Paper
Authors
- Khatam Aminoroayaee 1
- Tahere Amirabadi Farahani 2
- Golnaz Taasoli 3
- Saeid Karimi Dehkordi 4
- Fariba Rezaei Sarteshnizi 5
1 Department of Animal Science, Faculty of Agriculture, Shahrekord University
2 Department of Animal Science, College of Agriculture, Shahrekord University
3 Department of Animal Science, Chahatmahal Bakhtiari Agricultural and Natural Resources Research Center
4 Department of Animal Science, College of Agriculture, Sharekord University
5 Department of Animal Science,, Faculty of Agriculture, Shahrekord University
Abstract
Objective: Agricultural residues are used as part of ruminant diets. Optimal utilization of these materials and reducing their wastage is essential. Proper processing (treating) of these residues improve the palatability. Rice straw and rice bran are two major residues after rice harvesting and processing which, chemical processing mostly improve their digestibility. Chemical treatment weakens hydrogen bonding inside the rice straw; resulting in improved fiber digestion. Therefore, this experiment was carried out to study the effect of chemical processing (with nitric acid, sodium hydroxide, and sodium hypochlorite) as a desilication method on the chemical composition, fermentation parameters, and in vitro digestibility of nutrients of rice straw and rice bran and compare them wheat straw and bran.
Method: Desilication of rice straw and bran was carried out using nitric acid, sodium hydroxide, and sodium hypochlorite, pressure, heating and drying. The experimental treatments included 1- Straws: 1- wheat straw as positive control, 2- untreated rice straw, 3-treated rice straw and 2- Brans: 1- wheat bran as positive control, 2- untreated rice bran and 3- treated rice bran). Chemical composition, concentration of silica and in vitro gas production parameters and neutral detergent fiber digestibility of all treatments were measured and metabolizable energy, organic matter digestibility and short-chain fatty acids concentration were estimated.
Results: The results showed that chemical treatment reduced the contents of silica, crude protein, ether extract and ash in treated rice straw (P > 0.05) compared to the untreated rice straw. Potential of gas production, lag time, ammonia nitrogen concentration, total protozoa population, neutral detergent fiber, and acid detergent fiber were not affected by chemical processing of rice straw; however, gas production rate and estimated short chain fatty acid concentration increased (P > 0.05) and pH decreased (P < 0.05) in treated rice straw compared to untreated rice straw and wheat straw.
In vitro neutral detergent fiber digestibility tended to increase in treated rice straw compared to untreated rice straw and wheat straw. Dry matter, crude protein, ether extract and ash contents decreased and pH increased with chemical processing (P > 0.05). Furthermore, gas production potential, gas production rate, ammonia nitrogen concentration and neutral detergent fiber decreased in treated rice bran compared to untreated rice bran (P > 0.05). Lag time, total protozoa population, Epidinium and Entodinium population, estimated metabolizable energy, organic matter digestibility and short-chain fatty acids concentration were not affected by chemical treatment in rice bran.
Conclusions: Chemical processing of rice by-products by reducing anti-nutritional compounds such as silica and improving some fermentation and digestibility characteristics, facilitate use of fiber fraction of these material in the livestock diet.
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