Effect of replacing corn silage with alternative silages on quality, fatty acids and volatile compounds of Italian semi-hard raw milk cheese

This study involved 15 lactating cows during three consecutive periods of 21 days each with transition phases of 12 days. Three isonitrogenous and isoenergetic diets (14.5% CP; 38.7% NDF, 22.5% starch, 5.8 MJ/kg DM basis) were used in the first (CS: diet based on corn silage), second (SSS: corn silage was replaced by sorghum-soy silage) and third period (SS: corn silage was replaced by sorghum silage). During the last week of each period, bulk milk from two days was collected to produce six wheels of semi-hard raw milk “Latteria” cheese with 60 days of ripening. Cheese yield was not affected by the diet, averaging 7.03%. Dry matter (60.97% on average) and ash content (3.72% on average) of cheeses showed no significant differences. Cheese from SS had the highest fat content (30.08%), but the lowest protein content (25.29%). Color and physical parameters were significantly affected (P < 0.001) by the diet. Cheeses from the SS and SSS diets were brighter and yellower than cheeses from the CS diet. Moreover, cheeses from the SSS and SS diets presented higher values of hardness and cohesiveness and lower elasticity than those from the CS diet. Fatty acid profile was modified by the diet. Cheeses from SSS and SS, compared to CS, contained higher monounsaturated fatty acids (MUFA: 25.11 and 24.75 vs. 21.97% resp.; P < 0.001) and lower saturated fatty acids (SFA: 70.61, 70.94 vs. 73.77% resp.; P < 0.001). The atherogenic index and thrombogenic index were positively affected (P < 0.001) by the alternative crops, as they were higher for CS than for SSS and SS. In conclusion, the use of sorghum and sorghum-soy silages in dairy cow diets modified the color and physical properties of cheese, and improved not only the fat percentage but also the fatty acid profile by increasing monounsaturated fatty acids. For the first time, this study characterized volatile compounds of Latteria cheese and reported that they were affected by the type of silage in the diet.