Comparative survey of the effects of chemical preservatives and natural fermentation on microbial quality and IgG antibodies in order to increase shelf life of bovine colostrum.

BACKGROUND: Colostrum is the first milk produced after birth and is particularly rich in immunoglobulins, growth factors and antimicrobial peptides. Therefore, maintenance and storage of bovine colostrum has always been considered due to benefits of colostrum for the calf. Microbial contamination of colostrum is a concern because it is thought that bacteria in colostrum may interfere with passive absorption of colostral antibodies. OBJECTIVES: The aim of this study was to evaluate the effects of chemical preservatives and natural fermentation on quality and storage of colostrum. METHODS: Colostrum from the first milking of five Holstein cows was stored separately. Then colostrum samples were studied at days 1, 10, 20, and 30 of storage after treatment. All samples underwent microbiological culture for total plate count and detection of Escherichia coli, Coliforms, mold and yeast. Then whey was provided from untreated and treated samples at the end of 30th day and SRID (single radial immune diffusion) test was performed for assaying IgG antibody. Then the effect of treatments on colostrum antibody level was studied. RESULTS: The results showed that potassium sorbate did not have a role in reducing E.coli and coliforms count. However, it has prevented an increase in E.coli and coliform count during 30 days. Formic acid and propionic acid reduced the number of E. coli and coliform (p<0.05). In addition, the two organic acids promoted the growth of mold and yeasts compared with potassium sorbate. Nonetheless, the mentioned three treatments did not have an important role in reducing total count (p>0.05). The natural fermentation contributed to the decline of E. coli and coliform count while total count increased one day after treatment compared with other treatments, however among the treatments, formic acid and potassium sorbate were more effective than propionic acid and natural fermentation treatment for maintaining hygienic quality of colostrum. The result of measuring IgG antibody indicated that potassium sorbate has had more protective effect than other treatments. CONCLUSIONS: The results exposed that potassium sorbate and formic acid are better than other treatments to maintain colostrum quality with regard to increasing shelf life of colostrum.