Effect of different doses of cracked whole soybean on milk fatty acid composition in buffalo

In order to improve the health characteristics of buffalo milk and Mozzarella, the effect of two concentrates differing in linoleic acid (LA) content on milk fatty acid (FA) composition was con- sidered. Dietary LA supplementation, in fact, is the most effec- tive strategy to increase milk content of conjugated linoleic acid (CLA), which has potentially positive effects on human health. Thirty-two buffaloes were randomly allotted in two groups: exper- imental (EG) and control (CG). During the first period (P1, from 26 to 82 days in milk) EG fed a total mixed ratio (TMR) composed by barley silage, alfalfa and grass hay, maize meal and 3 kg of a concentrate composed by 30% cracked whole soybean (WS) and 70% horse bean (HB), which provided 12.6 g/kg DM of LA. During the second period, (P2, from 97 to 152 days in milk), the experi- mental concentrate was 70/30 WS/HB that provided 25.4 g/kg DM of LA. During both periods CG fed a diet based on the same for- age than EG and a concentrate composed by maize meal, soybean meal, and cotton seeds (7.2 g/kg DM of LA). Individual milk sam- ples were weekly collected and data of milk FA composition were analysed by a repeated measures model. At the end of each peri- od, milk from each group was separately processed and six Mozzarella cheese for group were sampled. During P1, LA con- tent of milk from EG was significantly higher than milk from CG (1.85 vs. 1.52% of TL), whereas CLA and vaccenic acid (VA) con- tent did not differ between groups. During P2, the LA content in EG milk was more than two times higher than that in CG milk (3.91 vs. 1.59% of TL). Also CLA (0.59% of TL vs. 0.38% of TL for EG and GC respectively) and VA (1.67%of TL vs. 1.25% of TL for EG and CG, respectively) milk content significantly differed between groups. Oleic acid (OA) content significantly differed between treatments, being higher in milk from EG (+17%). Interestingly, differences were observed also in the substrate/product ratio related to stearoil-CoA desaturase enzyme (SCD). This enzyme acts either on C18:0, that is con- verted in OA, and on C14:0, C16:0 and VA, which are converted in cis9 unsaturated FA. Results suggested a higher affinity of SCD for C18:0. The desaturation index of C18:0, in fact, was more than ten times higher than that of other substrates. The FA com- position of mozzarella reflected that observed in milk, confirm- ing that cheesemaking did not affect the transfer of FA from milk to cheese.