Use of Dried Stoned Olive Pomace in the Feeding of Lactating Buffaloes: Effect on the Quantity and Quality of the Milk Produced

Dried stoned olive pomace (DSOP) was administered to dairy water buffaloes, and their productive performance and milk composition were analysed. Sixteen pluriparous lactating buffaloes were divided into two uniform groups (control and experimental), taking into consideration the following parameters: milk production (2,192 and 2,102 kg) and duration of lactation (254 and 252 d) of the previous year, distance from calving (51 and 43 d), milk production (9.71 and 10.18 kg/d), body condition score (BCS) (6.44 and 6.31) and weight (617 and 653 kg) at the beginning of the trial. Both diets had the same formulation: second cut alfalfa hay 20%, corn silage 42%, concentrate 38% but the two concentrates differed in their formulation, the experimental one contained 15.50% of DSOP as fed. The employed DSOP showed high amounts of secoiridoids, such as 3,4-dihydroxyphenylethanol (3,4-DHPEA) (1.2 g/kg DM), 3,4-dihydroxyphenylethanol-elenolic acid di-aldehyde (3,4-DHPEA-EDA) (12.6 g/kg DM), p-hydroxyphenylethanol-elenolic acid di-aldehyde (p-HPEA-EDA) (5.6 g/kg DM) and lignans, which are known to be powerful bioactive compounds. The control diet had an energy-protein content of 0.86 Milk FU/kg DM and 143.3 g/kg DM of crude protein, whereas the experimental diet of 0.87 Milk FU/kg DM and 146.6 g/kg DM of crude protein. Each animal of the two groups received 17 kg DM/d and each buffalo of the experimental group, by way of the concentrate, ingested 1.05 kg DM/d of DSOP. The trial lasted 40 days. No significant difference was found between the BCS (6.41 and 6.53), live weight (625.93 and 662.50 kg) and milk production (9.69 and 10.08 kg/d) of the two groups, as was the case for fat, protein, lactose, pH and coagulating parameters of the two milks. The milk fat of the experimental group had a significantly higher content of total tocopherols (10.45 vs $8.60{\mu}g/g$, p<0.01) and retinol (3.17 vs $2.54{\mu}g/g$, p<0.01). The content of the reactive substances with tiobarbituric acid (TBARs) was significantly lower in the milk fat of the experimental group (12.09 vs $15.05{\mu}g$ MDA/g, p<0.01). The acid content of the milk fat of the experimental group had a significantly higher content (p<0.05) of C18:0 and of $C18:3{\omega}6$. LC-MS/MS analysis showed the presence of 3,4-DHPEA ($36.0{\mu}g/L$) in the milk of the DSOP-fed buffaloes, while other phenols were not found. DSOP, in the quantity utilized, can be used in the feeding of the lactating buffalo; the dietetic-nutritional characteristics of the milk are improved due to a greater contribution of tocopherols, retinol and the presence of hydroxytyrosol.