Fragilidade de fibra e uso de inoculantes propiônicos em silagens

Abstract

Fiber fragility refers to the rate at which forage particles reduce in size during chewing or laboratory simulation chewing action. The present study was conducted with the objective of evaluating: 1. the fragility of fiber from winter pastures and corn silage, relating it to bromatological composition and in situ degradation; 2. the effects of Propionibacterium inoculation on ensilage using a meta-analysis approach. In the first test, 25 samples of corn silage and 25 samples of winter pastures (oats, ryegrass and wheat) were collected, between the months of June and December 2022, on properties in the Central region of Rio Grande do Sul. The samples were analyzed for dry matter (DM) content, neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL) and crude protein (CP). The evaluation of in situ degradation was evaluated after ruminal incubation for 48 h. The fiber fragility analysis was carried out according to the Miner Institute method. Corn silage had higher DM, NDF, ADF and LDA contents compared to winter pastures. However, the FDA:NDF ratio was similar between materials. Winter pastures had higher CP content and DM and NDF degradation. Fiber fragility was greater in corn silage. The degradation of DM and NDF had a negative correlation with the contents of FDA, NDF and LDA and the FDA:NDF ratio. Fiber fragility showed a negative correlation with DM and NDF degradation, and positive correlations with ADF, NDF, LDA and DM. The relationship between fiber fragility and the FDA:NDF ratio was positive. A systematic search was performed in peer-reviewed journals using Google Scholar, Web of Knowledge, and ScienceDirect, with the aim of conducting a metanalysis study. This search resulted in 142 treatment evaluations in 40 studies. The data were analyzed considering the random effect of the study and pre-defined fixed effects. In general, Propionibacterium inoculation increased the propionic acid content by 215%, tended to decrease fungal and yeast counts and tended to increase the aerobic stability of the silage. The effect of inoculation on silage butyric acid, dry matter recovery and neutral detergent fiber content was dependent on silage pH. Propionibacterium decreased the NDF and butyric acid content and tended to increase DM recovery in silages with high pH. There was no effect of the inoculation and storage period interaction on the fermentation profile and aerobic stability of the silage. Thus, the fragility of corn silage fiber is higher than that of winter pastures, while the ADF:NDF ratio remained constant between materials. Fragility increases with increasing fiber content and reducing the degradation of materials. Degradation coefficients are the best indicators to predict fiber fragility in winter pastures and corn silage. Inoculation with Propionibacterium reduces the growth of fungi and yeasts, increases the propionic acid content in silage and improves aerobic stability. Furthermore, silage pH affects the role of microbial inoculants in ensiling.