Whole exhausted berries of Myrtus communis L. supplied to dairy ewes: Effects on milk production traits and blood metabolites

Abstract

Exhausted myrtle berries (EMB) is a by-product of the maceration process of myrtle (Myrtus communis L.) berries to produce a commercial liqueur called Mirto. This study evaluated the effect of the dietary inclusion of EMB on milk production traits, milk coagulation properties, liver and kidney metabolic activity and nitrogen balance in lactating dairy ewes. Thirty Sarda dairy ewes were randomly assigned to 3 dietary treatments consisting of a control diet (CON), a diet supplemented with 50g/d per head of EMB (EMB50), or a diet supplemented with 100g/d per head of EMB (EMB100). The study lasted 13 weeks, with 2 weeks of adaptation period and 11 weeks of experimental period. Milk yield was measured and milk samples were collected weekly and analyzed for fat, protein, casein, lactose, milk urea (MU) content and somatic cell count (SCC). Milk samples collected every two weeks were analyzed for milk coagulation properties. Blood samples were collected on d 0, 15, 30, 45 and 60 of the experiment by jugular vein puncture and analyzed for hematological parameters, albumin, alkaline phosphatase (ALP), bilirubin, creatinine, gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), protein, blood urea (BU), and serum protein fractions. Dietary treatments did not affect milk yield, composition and coagulation properties, except for MU, which decreased as the dose of EMB in the diet increased, and SCC. Diets did not influence hematological, kidney and liver parameters, except for BU content and blood protein, which decreased with the inclusion of EMB in the diet. The reduction in MU and BU as EMB dose increased suggests that the EMB use might positively affect the dietary nitrogen use. The limited variation in milk production traits, and hematological and metabolic parameters suggests that EMB can be included in the diet of dairy ewes without adverse effects on milk production and health status.