Different Techniques to Study Rumen Fermentation Characteristics of Maturing Grass and Grass Silage

Abstract

Grass samples were harvested during the 1993 growing season after a precut on April 27, 1993 and were stored frozen or left to ensile in 30-L buckets. Effects on chemical composition and fermentation kinetics of the maturation of the grass and of ensiling were investigated. Chemical composition and fermentation kinetics were determined using the gas production technique, in vitro techniques, and the nylon bag technique. Two silage samples were also investigated in vivo. Maturation caused a decrease in crude protein content and organic matter degradability and an increase in neutral detergent fiber, acid detergent fiber, and lignin contents. Degradation rates were highest for the youngest samples and decreased as grass and silage matured. This result could be observed from the first derivative of the cumulative gas production curves (i.e., the rate of gas production) and from the gas production parameters. The rate of degradation of the nonsoluble fraction of the young samples, determined using the gas production technique, was relatively higher in rumen fluid from a cow fed silage from grass cut at a young stage. More mature samples were degraded relatively faster in rumen fluid from a cow fed mature grass silage, suggesting a specific adaptation of the rumen microorganisms to the grass properties. There was a good relationship among the second phase of gas production (i.e., fermentation of the nonsoluble fraction), maturity of the grass and grass silage samples, degradability determined with the Tilley and Terry technique, and degradability determined after 46 h of incubation in rumen fluid. Results obtained with both of the different in vitro techniques and the nylon bag technique were confirmed by the in vivo experiments involving the two silage samples.

Effect of maturity at harvest onin vitromethane production from ensiled grass

“…The general decrease in CP content and the increase in cell wall content (NDF and 219 ADF) with increased maturity was expected and in agreement with other reports (Rinne 220 et al, 1997; Cone et al, 1999). Of interest though is the fact that the CP content was 221 similar for the silages from grass harvested in June and August.…”

Comparison of in vitro gas production technique with in situ nylon bag technique to estimate dry matter degradation

“…Cone et al (1998) showed in grass samples fertilized with different N-levels and harvested from late spring to late summer that both the rate and the extent of OM degradation determined in situ could be predicted by gas production parameters. Cone et al (1999) also showed that there was a close relationship between in situ degradation characteristics and gas production parameters for grass silage samples differing in maturity.The highly significant relationship between gas production and dry matter disappearance data suggests that the extent of dry matter degradation can be predicted from in vitro gas production.A possibility of applying in vitro gas production methods to study the kinetics of forage DM degradation instead of the in situ technique will have advantages, including avoiding the error associated with the loss of small particles through the pores of nylon bag and reducing the cost. …”

“…Sci., 50, 2005 (2): 60-67 Original Paper et al, 1999Cone et al, 1999Cone et al, , 1998Cone et al, , 2002. However, the information available can be considered limited and results somewhat inconsistent.…”

Cinética de fermentação ruminal in vitro da forrageira Brachiaria brizantha cv. Marandu em sistema silvipastoril

“…Os sistemas Em sistemas de produção em pasto, é de fundamental importância conhecer o valor nutritivo das forrageiras (Euclides et al, 2009). O conceito do termo valor nutritivo refere-se à composição bromatológica do alimento, sua cinética de fermentação ruminal, sua digestibilidade aparente da energia e seu consumo voluntário por ruminantes (Crampton et al, 1960;Mott, 1970).…”