Comparison between two hay based diets in buffalo nutrition: microbiological characteristics of milk, curd and mozzarella cheese

Abstract

Two groups of twenty milking Mediterranean buffalo cows were fed two diets, with the same energy and protein content, based on Italian ryegrass hay (diet G1) and Italian ryegrass hay silage (diet G2). Presumptive lactobacilli and lactococci were determined on milk, curd and mozzarella cheese, collected at 30, 60, 90 days from the beginning of the trial. Milk and mozzarella cheese at 30, 60, 90 days showed significantly higher microbial counts in diet G2 with respect to diet G1, apart from lactococci in milk at 90 days. For curd at 30, 60, 90 days the numbers of lactobacilli and lactococci in diet G1 were significantly higher with respect to diet G2, apart from lactococci at 30 days. Genetic analysis by 16S rDNA characterization of colonies, randomly isolated, showed in diet G2 also the presence of not lactic species. Probably Italian ryegrass hay silage, present in diet G2, could bring bacteria in the environment and consequently in the milk that are detrimental for the proper growing of lactic microflora in the curd and that are resistant to the high temperature used in the mozzarella cheese making process.