Effect of extruded linseed on sarda donkey milk quality

Abstract

The aim of this work was to evaluate the effect of extruded linseed in donkey diet on milk yield, milk composition and milk fatty acids (FA) profile. Eight Sarda donkeys were allocated to two groups homogenous for milk yield (0.354 ± 124 kg/d), days in milking (123 ± 41 d), and body weight (110 ± 15 kg). The first group was fed a control diet (CON), while the second group was fed the control diet supplemented with 100 g/day per head of extruded linseed (ELS). The trial lasted 7 weeks, with 2 weeks of adaptation and 5 weeks of experimentation. Data were analysed using a linear mixed model, considering the diet, sampling time and their interaction as fixed effects and animals as random effect. Milk yield and milk chemical composition were not affected by the diet. The diet led to some variations of FA profile. Long-chain FA, unsaturated FA and polyunsaturated FA were higher in ELS compared to control group. These results reflected the trend of some individual FA, in particular the concentration of alpha-linolenic acid. This FA was affected by diet, sampling time and their interaction and, at the end of the trial, the average value was double in ELS than CON. Dietary linseed reduced thrombogenic and atherogenic indices and increased hypo-to hypercholesterolemic ratio of milk. In conclusion, extruded linseed can be used in donkey diet to improve the milk FA profile, in terms of polyunsaturated FA and nutritional indices, which could have a positive impact on human health. Highlights The valorisation of donkey milk could be a good strategy to preserve donkey native breed. Extruded linseed, rich in alfa-linolenic acid, improves fatty acid profile of donkey milk, increasing PUFA and decreasing SFA. Linseed supplementation affects positively milk nutritional indices.