Two field experiments were conducted during two successive summer growing seasons 2013 and 2014 in an administration field at Meet Gaber village, Belbais District, Sharkia Governorate, Egypt. The experiment aimed to study the effect of four planting densityies (D1:70000 plants/fad., D2: 105000 plants/fad., D3:140000 plants/fad.; D4: 210000 plants/fad.) and three nitrogen fertilizer levels (N1: 15 kg N/fad./cut; N2:30 kg N/fad./ cut; N3: 45 kg N/fad./cut) on fresh weight /plant, fresh forage yield/fad., as well as  crude protein and fiber contents in leaves and stems at 1^st and 2^nd cut of three forage sorghum genotypes (G1: Sudan grass (Sorghum sudanense (Piper) Stapf, cv. Giza 2),G2: sweet sorghum  (S. bicolor L. Moench, cv. Giza 1), and G3: sorghum (S. bicolor L. Moench) x Sudan grass (S. sudanense (Piper) Stapf, cv. Surdan) as an interspecies hybrid. The obtained results could be summarized as follows: Sudan grass was superior in fresh weight /plant, fresh forage yield /fad., where sweet sorghum was superior in crude protein and fiber contents. Using planting density 70000 plants/fad., had a significant increase in fresh weight /plant, crude protein and fiber content in leaves and stems. Fresh forage yield/fad., was significantly increased due to increasing planting density up to 140000 or 210000 plants/fad., at 1^st and 2^nd cut in both seasons and their combined analysis. The increase of N level up to 45 kg N/fad., caused a significant increase in the aforementioned characters, except crude fiber content which significantly decreased at 1^st and 2^nd cut in both seasons and their combined analysis.