Effect of using different fertilizers sources on forage sorghum yield, digestibility and energy parameters by In vitro Gas Test production

The effect of using different rates of organic and mineral fertilization on forage sorghum was studied. An experiment was conducted at the Agricultural Research and Experimental Station, Cairo University in 2013 and 2014 summer seasons. The experiment was performed in a randomized complete design with three replicates. The experiment included five treatments; the T₁ (control)= 100% mineralization, T₂ (C₆M₀) =100% compost, T₃ (C₄.₅M_25%) = 25% minerals + 75% compost, T4 (C₃M_50%)= 50% minerals+50% compost and T₅ (C₁₅M_75%) = 75% minerals+25% compost. The results showed significant increases in plant height, stem thickness, fresh weight and dry weight for the T₃ compared with the other treatments, while means value were 152.4 cm, 1.047 cm, 22.96 ton. /fed and 6 ton/fed, respectively.  Moreover, T₃ (C_4.5M_25%) led to increasing the content of CP and NFE and did not affect the EE and ash. While this treatment led to increasing the content of NDF%, ADF% and decreasing the content of hemi cellulose and higher content of cellulose compared to the other treatments. The results of gas parameters correct (GP ml /200 mg DM), gas production structure fraction (GPSF %) and gas production non-structure fraction (GPNSF %) recorded the best values with the T₂ (C₆M₀).  The highest values of each of (GP ml / 200 mg. DM), (GPSF %) and (GPNSF %) was recorded in the 1^st and 2^nd cut, while the T₄ (C₃M_50%) gave the highest value in the 3^rd cut.  The T₂ recorded the highest values ​​of ME (MJ / Kg. DM) in the 1^st cut and the net energy lactation (NEL_MJ/kg._DM) in the 2^nd cut. The short-chain fatty acids (SCFA, s m _{mol / ml. gas}) showed the highest values ​​in the 1^st and 2^nd cut, while for the T₄ (C₃M_50%) showed the highest values ​​in the 3^rd cut. The T₂ recorded a significant increase in dry matter and organic matter digestibility in the 1^st cut followed by the T₄ which recorded the highest value in the 1^st cut. The economic study proved that the T₃ (C_4.5M_25%) has the highest profit (2.29 L.E.), the T_{4 =} (2.46 L.E.) and the lowest return of the T₂ = 100% organic gave a profit of (1.90 L. E.). The T₂ gave the highest digestive value for the 1^st and 2^nd cut, followed by the T₄ which gave the highest digestive value in the 3^rd cut. Finally, we can conclude that the T₂ is the best treatment in terms of feeding animal and the size of the crop in the 2^nd cut is like the size of the crop in the 3^rd cut of the T₄, which gave the best economic feasibility using the 2^nd cut of the T₂ to provide the time of cultivation for another crop. In addition, necessary  work of the digestion and  feeding trails on the animal on these 2^nd cut of T₂ which gave positive results in order to link the amount of yield in the 1^st  and 2^nd  cut and digestion factors and measure the amount of meat produced to determine the economic efficiency in obtaining a good crop in arms of quantity and quality and reduce the crop duration to provide land for cultivation another crop as well as reducing the mineral contamination of the fertilizer-producing soil.