Relationships among diet, plasma and milk total polyphenol content in milking goats

Some Mediterranean forages are interesting for their polyphenol content, which may perform beneficial functions to animal and nutraceutical effects on consumer. In ruminants, the fraction transferred into the milk may reflect the feeding regime and thus used as biomarker for the diet traceability. In order to highlight the relationships among polyphenols in feed intake, plasma and milk, total polyphenols was measured in the diets used by goats and in the corresponding plasma and milk. During March-May, twelve Girgentana goats, averaging 37.2 kg live weight, 86 days in milk and 2.0 kg milk yield were allocated to three groups and, according to a 3 x 3 Latin square design with three periods of 21 days (14 days for adaptation and 7 days for measuring and sampling), fed with three diets in succession: sulla fresh forage (SFF), sulla fresh forage plus 800 g/d barley meal (SFB), mixed hay plus 800 g/d barley meal (MHB). During each period, offered and refused feed of each goat were weighed daily, sampled twice and disaggregated into botanical parts to estimate the mean amount and the quality of feed intake; the individual milk yield was recorded daily and samples of milk and blood were collected at the end of each period. During each period, observations means of total polyphenols intake (ItP), and the corresponding total polyphenols in plasma (PtP) and milk (MtP) were used for Pearson correlation. Due to the polyphenols content of sulla forage, such as condensed tannins, the SFF and SFB diets increases ItP (9.21 and 9.29 vs. 2.84 g GAE/d; P<0.001), PtP (304 and 309 vs. 294 microg/ml GAE; P<0.05) and MtP (0.964 and 1.081 vs 0.819 g GAE/d; P<0.05). During the first period of experiment (March), a positive correlation between ItP and MtP was detected (r=0.60; P=0.040). This relationship might depend on a high percentage of leaf blade in the fresh forage ingested in this period compared to the others. Also, ItP and PtP content showed a positive correlation (r=0.61; P=0.038). Regarding all experimental periods, a positive correlation between plasma free polyphenol content and MtP content was found (r=0.38; P=0.031). Our results suggests that polyphenol content in animal diets is reflected in milk