Nutritive value of wheat straw treated with gaseous or liquid ammonia trough nylon bag and in vitro gas production techniques

Introduction Feed shortage is the most important characteristic of Iranian animal industry. Increased costs of livestock production have caused the Iranian producers to reduce feed costs mainly by inclusion low quality crop residues into ruminants diets. It is estimated that around 20 million tons wheat straw produced in Iran every year. Both the digestibility and crude protein content of wheat straw are typically low. Since 1900, a wide variety of chemical treatments have been tested for their potential to improve the feeding value of wheat straw. Upgrading of wheat straw by ammoniation has been known for a long time, but application of this method of wheat straw treatment has received the least attention in the area (Khorasan Province, Iran). Therefore, the object of the present study was to evaluate the effect of gaseous and liquid ammonia on nutritive value of wheat straw through in vitro techniques.
Material and Methods One kg dry wheat straw was placed into the plastic cylinders with dimension of 1 m (diameter) and 1.8 m (height) and 0.8 mm (thickness). Gaseous and liquid commercial ammonia was injected or added to the wrapped straw at the rate of 2, 4 and 6 percent. The treatment time was 1 month at room temperature (20-25 ºC). At the end of treatment period the cylinders were opened and the ammoniated straw exposed to the air for 4 days. The treated straws were sampled for the subsequent analyses. Dry matter degradability of the samples was done by using nylon bags (10x20 cm) with pore size of 40 micron. About 2 g ground samples (2 mm) were placed into the nylon bags and incubated in rumen of 4 permanently fistulated steers for 3, 6, 12, 24, 36, 48, 72, 96 and 120 hrs. The experimental steers were fed by the ordinary diet containing 65% forage and 35% concentrate twice daily. The Menke and Steingass method was followed for the in vitro gas production method.
Result and discussion Crude protein (CP) content of the treated wheat straw samples increased and their neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents reduced significantly (PConclusion The overall results showed that wheat straw treatment with 6% ammonia in either gaseous or liquid forms could improve its feeding value for ruminants significantly (P