Silagem de colostro bovino: aspectos físico-químicos e microbiológicos em diferentes tempos fermentativos

Abstract

Bovine colostrum contains proteins, lipids, lactose, immunoglobulins, insulin-like growth factor I, transforming growth factor beta-2, growth hormone, leukocytes, among others, these being essential to newborn animals, mainly in the first hours of life. However, during lactation, colostrum has a reduced composition and the volume produced by animals is higher than that consumed by calves. Bovine colostrum silage is an alternative to preserve through anaerobic fermentation and has a physicochemical composition superior to colostrum and raw milk, allowing storage for up to two years. However, there are few studies on bovine colostrum silage, providing a gap in relation to the transformation kinetics of the composition and microbiota over the fermentation time. Thus, the objective of the present work was to evaluate the physicochemical and microbiological characteristics of bovine colostrum silage at different fermentation intervals. The samples of bovine colostrum (n=21) were placed in 500 mL plastic bottles, stored and fermented for 61 to 437 days. The physicochemical parameters evaluated in the silage were acidity, protein, total solids and ash, using the methods of the Adolfo Lutz Institute (2008). The microbiological characterization followed the methodology of Saalfeld et al. (2013) with adaptations, and the identification of isolated microorganisms was performed by means of Gram stain and biochemical tests. The acidity, protein and total solids during the fermentation intervals (group 1: 61 to 154, group 2: 200 to 273 and group 3: 280 to 437 days) were not significant. The ash concentration had a significant reduction (P <0.05) in groups 1 and 3. There was a positive correlation between total solids, protein concentration and ash with fermentation intervals. The microorganisms found in the silage were: Lactobacillus spp. (95.2%), Staphylococcus spp. (42.9%), Corynebacterium spp. (19.0%), Enterococcus spp. and Bacillus spp. (14.3%), Lactococcus spp. and unidentified (9.5%), Leuconostoc spp., Streptococcus spp., Actinomadura spp. and Escherichia spp. (4.8%). The composition of colostrum silage was superior to colostrum and milk as reported in studies available in the literature. However, the presence of pathogenic microorganisms such as Streptococcus spp., Staphylococcus spp. and Bacillus spp. in silage it is worrying, taking into account the health of the animals that can receive this food, being necessary to look for ways to control the colostrum contamination and consequently of the silage.