Fatty acid metabolism in lambs fed hazelnut skin as a partial replacer of maize

The aim of this study was to investigate the effect of dietary inclusion of hazelnut skin (HS) on growth performances and fatty acid metabolism of lambs. Twenty-two lambs were assigned to 2 treatments and fed ad libitum for 56 days: a maize-barley based diet (CON group) or a diet containing 150 g/kg on a dry matter (DM) basis of HS to replace maize (HS group). After slaughter, samples of muscle, rumen and abomasum digesta were collected and analyzed for fatty acid composition. The dietary inclusion of HS did not affect the DM intake, final body weight, carcass weight and average daily gain (P > 0.05), whereas feed conversion ratio was increased by HS diet (P = 0.014). Ruminal fluid pH, ammonia and total volatile fatty acids were not affected by the dietary inclusion of HS (P > 0.05), while HS diet increased the molar proportion of butyrate and reduced the proportion of valerate (P < 0.05). Replacing 150 g/kg dry matter maize with HS increased the concentration of vaccenic acid in ruminal digesta, abomasum content and intramuscular fat (P < 0.01). Polyunsaturated fatty acids (PUFA) of muscle were increased by hazelnut diet (P < 0.05). Although PUFA n-6/n-3 ratio was lower in the control treatment (P < 0.001), atherogenic and thrombogenic indexes were not affected by dietary treatment (P> 0.1). In conclusion, these results suggest that HS could replace 150 g/kg DM of maize without affecting animal performances and increasing the muscle concentration of PUFA and vaccenic acid.