The objective of this work to determine Kinetics of ruminal fermentation of silages of different fractions of the aerial parts of cassava varieties by technical semiautomatic gas production. The experiment was conducted in a completely randomized design with four replications, arranged in a 4x3 factorial design, four varieties of cassava (Amarelinha, Sabará, Olho Roxo e Periquita) and three fraction of shoots (upper, left over planting and whole plant). The material was ensiled in mini-silos of PVC, being opened after 56 days of fermentation. Silage samples were collected and submitted to pre-dried, ground and then proceeded to test gas production in vitro. The pressure readings of the gases produced during fermentations were performed at 2; 4; 6; 8; 10; 12; 15; 18; 21; 24; 30; 36; 48; 72 and 96 hours after the start of incubations. Pressure readings were made of gases through pressure transducer and subsequently adjusted to the volume of gases. The major ruminal DM disappearance occurred in times between zero and 24 hours. The highest yields of gas per hour were obtained at approximately 48 hours of fermentation for variety in Shiner fraction entire plant. The silages of different varieties and fractions of cassava shoots have the same potential for gas production. However, silage variety of Hopscotch fractions in the upper third of shoot and leftover planting have better effective degradability and potential.
degradability; digestibility; roughage; ruminant