Abstract:
The present work was carried out to screen and test five oyster mushroom strains , brought from Institute of Forest Botany, Gottingen University, Germany , towards their ability to grow on and upgrade corn stalks during the two winter seasons of 1998 and 1999 .The five strains were : “Pleurotus v. florida (8), P. ostreatus v. florida(49), P. sajor – caju (103 ), Pleurotus.sp. (112) and P. sajor caju (117) “. These cultures were grown on potato dextrose agar medium (PDA). A Piece of mycelium media was used to inoculate 200 g of sterile sorghum seeds in 250 ml. bottles.
When the seeds were fully covered with mycelium (30 days at optimum temperature “25ºC”), they were used to inoculate chopped, wet and pasteurized corn stalks.
The inoculated corn stalks was placed in plastic cages (40 ×25×30 cm ) . The cages were covered with plastic sheets and opened after the mycelium covered the surface of corn stalks (incubation period 21 days). The first fruiting bodies were harvested 10 – 12 days later.
Four harvests were carried out during the next 60 days. The highest yield of fresh fruit bodies was obtained by P. ostreatus v. florida (49) followed by Pleurotus v. florida (8) being 233 and 215 gm / wet kg substrate respectively.
Fiber fractions analysis showed that, cellulose and hemicellulose content in raw corn stalks decreased by such treatment due to the growth of all the 5 strains of fungi.
Strains Pleurotus v. florida (8) and Pleurotus. sp. (112) were the best effective strains for cellulose and hemicellulose degradation.
The effect of fungi treatment on lignin content was not obvious.
The crude protein content of corn stalks was increased due to the growth of strs. P. sajor – caju (103), Pleurotus.sp. (112) and P. sajor caju (117); the highest protein increase (90% over the untreated corn stalks level) was recorded by Pleurotus. sp. (112).
The In vitro dry matter digestibility (IVDMD) was improved markedly by biological treatment with Pleurotus sp. (112) and P. sajor – caju (103) of spent corn stalks compared with raw corn stalks.
Also hemicellulose, cellulose and lignin - IVDMD were improved.
The best improvement was obtained by Pleurotus sp. (112) followed by P. sajor – caju (103). Therefore Pleurotus sp.112 was chosen for performing In-vivo digestibility with sheep.
In general, it is clear that biological treatments with Pleurotus sp. 112 improved the quality of roughage.
Therefore, by this technique an important amount of the treated roughage would be available to be utilized as animal feed which also be helpful to clear the environment.
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