Abstract: The rumen digestion trial was conducted to determine the effects of new bred sorghum forages in rumen of lactating cows on digestibility of energy. Sorghums in this experiment came from new bred variety, were respectively No.1 Tiannong sorghum forage A and No.1 Tiannong sorghum forage B, which dried by nature air with grains and straw. Two ruminant fistula lactating cows were used in this experiment. Two sorghum forages respectively was incubated and removed in rumen after 0, 2, 4, 8, 12, 24, 36, 48, 72 h, It was observed that sorghum forages resulted in energy digestion. The energy digestibility have respectively significantly difference at 0, 2, 4, 8, 12, 24, 36, 48, 72 h from sorghum forage A or sorghum forage B. The energy of sorghum forage A and sorghum forage B, were respectively 11.22 and 15.38 MJ/kg. The energy digestibility of sorghum forage A and sorghum forage B, were 59.41% and 62.69% at 72 h in rumen respectively. The planting technique of sorghums was able to affect the digestibility of energy. The physical and chemical performance of bred sorghum affected the digestion in rumen.

Key words: bred sorghum; lactating cows; energy; rumen digestibility