Influence of different livestock production systems in caprine milk and cheese odd and branched chain fatty acids (OBCFA) composition

Odd and branched chain fatty acids (OBCFA) are produced by rumen biochemical mechanisms and by mammary lipogenic activity of ruminants. Although OBCFA represent a lesser component of milk, they are recognised as important bioactive components because of their positive role in gastrointestinal microbial ecology and their potential anti-cancer activity. In this study, we investigated the influence of the livestock production system on milk and cheese fatty acid composition of three different small goat farms: a conventional Saanen farm (CS) characterised by local ryegrass hay based diet, a conventional Alpine farm (CA) with dairy goats fed with alfalfa hay based diet and an organic Alpine farm (OA) characterised by grazing. Bulk raw milk samples were twice a month sampled from March to October and fresh cheese samples were monthly collected in the same period. Fat was extracted according to Folch (1957) and fatty acids methyl esters were prepared by base catalysed methanolysis of glycerides as described by Christie (1982) and analysed by gas-chromatography. Data were analysed by one way ANOVA and multivariate statistic (PCA). Results showed significant differences in the composition of fatty acids in goat milk and cheese. Particularly, OBCFA showed a satisfactory discriminant capacity for the livestock production system. Samples coming from the conventional Saanen farm (CS) resulted enriched in SFA and PUFA, whereas OA and CA milk and cheese were higher in MUFA and OBCFA. The highest OBCFA value (4.66%) was detected in milk of OA farm goats fed with the highest quantity of fibre, incoming from fresh grass and forage. On the contrary, Saanen goats, not grazing and fed with a higher quantity of concentrate, produced milk lacking in OBCFA (3.92%). The highest values of C13:0 and C15:0 resulted in OA milk (0.13% and 1.14%, respectively) at different level, if compared to CA and CS farm. C17:0 values resulted higher in OA (0.70%) and in CA (0.75%) than in CS (0.57%); we obtained similar results for C17:1, higher in OA (0.33%) and CA (0.32%) milk, than in CS (0.22%) milk. Cheese samples mirrored the same trend for OBCFA values observed in milk, with higher values in OA and CA than in CS. Considering the whole OBCFA, there were no statistically significant differences between OA and CA samples (4.95% and 4.82%, respectively) in fresh cheese. However, these samples showed a difference if compared to cheese samples coming from the conventional farm (4.14%).