Effect of the inclusion of Opuntia ficus-indica cladodes in the feeding of Cinisara cows on Caciocavallo Palermitano cheese produced in summer

In Sicily, the cladodes of Opuntia ficus-indica are used as fresh supplementation for livestock in summer, season characterized by low fresh pasture availability. The effect of cladodes’ integration on characteristics of milk and cheese from Cinisara cows was investigated. In June–July, 16 multiparous cows, that calved in the autumn-spring period, were subdivided into 2 homogeneous groups that, in a 2 × 2 Latin square design, with 2 phases, were fed different diets named control (CN) and cladode (CL). Group fed CN grazed natural pasture (standing hay) supplemented with 4 kg/day per cow of wheat bran, whereas group fed CL received the same diet of group CN supplemented with 15 kg/day per cow of fresh cladodes. In each phase, with bulk milk from each group, 2 cheesemaking was carried out, producing three forms of ‘caciotte’ for each cheesemaking. After salting, one ‘caciotta’ cheese was sampled and tasted, while the remaining 2 were vacuum maintained at 4 °C, and sampled and tasted after 15 and 30 days, respectively. Cladodes had low contents of crude protein (6.8% DM) and fiber (34.5%, 25.7%, and 3.0% DM for NDF, ADF, and ADL, respectively), high levels of α-linolenic acid (C18:3n-3, ALA) (19.1% FA) and polyphenols (16.7 mg GAE/ kg DM), and an antioxidant capacity (TEAC) equal to 106.1 mmol TE/kg DM. In milk, the cladodes’ integration reduced only the urea content (15.5 vs 18.5 mg/100 mL; p = 0.008), while in cheeses it influenced more parameters. In particular, products of group CL showed higher polyphenols (6.0 vs 4.7 mg GAE/kg DM; p = 0.04) and antioxidant capacity (50.7 vs 49.7 mmol TE/kg DM; p = 0.04). In relation to fatty acid (FA) profile, CL cheeses were higher in saturated FA (59.7 vs 57.7% FA; p = 0.002), except C18:0, and, among unsaturated FA, in vaccenic acid (C18:1t11) (0.44 vs 0.39% FA; p < 0.0001), rumenic acid (C18:2c9t11, CLA) (0.81 vs 0.78% FA; p = 0.008), and ALA (0.47 vs 0.33% FA; p < 0.0001). At sensory level cheeses from CL diet were more appreciated (5.7 vs 4.9; p = 0.001), showing greater color intensity (4.6 vs 4.1; p = 0.013), smell (6.0 vs 5.2; p < 0.0001) and buttery flavor (5.1 vs 4.5; p = 0.001). No difference due to storage time were observed. In summer the cladodes may represent a valid fresh by-product integration, contributing to increase the bioactive molecules in cheese as well as the liking of consumers.