Estimation of Fiber Fragility and Digestibility of Corn Silages and Cool Season Pastures

Fiber fragility is defined as the particle size reduction rate during chewing and can help to explain the effects on feed intake and animal performance of different fiber sources. This study aimed to estimate the fiber fragility of corn silage and cool-season pasture based on their chemical composition. Between June and December 2022, 25 samples of corn silage and 25 samples of cool-season pasture were collected from dairy farms in the state of Rio Grande do Sul. The samples were analyzed for particle size distribution, chemical composition, and fiber fragility. Contents of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and fiber fragility were greater in corn silages compared to cool-season pasture. However, the ADF–NDF ratio was similar in forages. Crude protein (CP) content and the in situ degradation of DM and NDF were greater in cool-season pasture than corn silage. Dry matter and NDF in situ degradation were negatively correlated with increased contents of ADF, NDF, and ADL and the ADF–NDF ratio in forages. Fiber fragility was negatively correlated with DM degradation and positively correlated with contents of ADF, NDF, ADL, and DM. Fiber fragility decreased as CP content increased. Thus, greater fiber fragility may jeopardize nutrient degradation, and levels of fiber fragility are directly associated with fiber content.