Tropical grass digestibility assessed by the mobile bag and in vitro methods in horses.

The research article evaluates the effectiveness of two different methods – the in vivo mobile nylon bag method and the in vitro method – to assess the digestibility of five types of tropical grass in horses. The study found no significant difference between the two methods in assessing nutrient digestibility for two of the grass types, but notable differences for the other three grasses.

Research Design and Procedure

• The study used a 2×5 factorial design with randomized blocks, featuring two different methods (in vivo and in vitro) and five types of grasses: Tifton 85 hay, sixweeks threeawn grass, Alexandergrass, capim-de-raiz, and Sabi grass.
• In the in vivo method, the digestibility of the grasses was assessed by passing them in nylon bags through the digestive tract of five horses.
• The in vitro method, on the other hand, assessed the grasses’ digestibility by subjecting them to a digestive process under a controlled laboratory setting, using horse feces as a source of inoculum.

Digestibility Comparison of Grass Varieties

• The results showed no significant difference between the in vivo and in vitro methods in assessing the digestibility of Sabi grass and sixweeks threeawn.
• However, Tifton 85 was the only grass that showed significant differences between the two methods concerning the apparent digestibility of all nutrients.
• Alexandergrass, Tifton 85, and capim-de-raiz showed the best digestibility of dry matter, neutral detergent fiber, acid detergent fiber, and organic matter when assessed using the mobile bag method compared to the in vitro method.
• Tifton 85 and capim-de-raiz demonstrated higher crude protein digestibility using the mobile bag method than with the in vitro method.

Retention Time of Grasses in the Horses’ Digestive Tract

• One factor considered in the study was the amount of time that the nylon bags (containing the grass samples) stayed in the horses’ digestive tract, averaging approximately 43.69 hours.
• The bags containing sixweeks threeawn and Sabi grass had significantly shorter retention times than those with capim-de-raiz and Alexandergrass.

Overall Conclusion

• The study concludes that the in vitro method can effectively replace the mobile nylon bag method for assessing the digestibility of sixweeks threeawn and Sabi grass in horses.