Effect of grape by-products inclusion on ruminal fermentation, blood metabolites, and milk fatty acid composition in lactating Saanen goats

Abstract

Grape by-product is one of the distillery industries which could be used in animal nutrition. In this 60-d trial, 16 lactating Saanen goats were assigned to four homogeneous groups and fed as follows: (1) control (CON) diet, (2) diet supplemented with 50 g/kg dry matter (DM) of grape by-product (GPB5), (3) diet supplemented with 100 g/kg DM of grape by-product (GPB10), and (4) diet supplemented with 150 g/kg DM of grape by-product (GPB15). The dry matter intake and apparent total-tract digestibility of DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were not affected (P>0.05) by grape by-products supplementation. Ruminal fermentation characteristics include pH and NH3-N were not affected by GBP treatments (P>0.05). Supplementing with GBP reduced propionate (P=0.06) without effect on other volatile fatty acids (VFAs). Increasing the percentage of grape residues to 10% of the total diet had no significant effect on goat milk production (P>0.05), but milk fat and protein percentage decreased in diets containing GBP (P<0.05). Plasma concentrations of glucose, cholesterol, and total protein were not affected by dietary treatments, but plasma concentration of triglyceride increased in GPB15. Inclusion of grape by-products in lactating Saanen goats diets had no significant effects (P>0.05) on the concentration of major classes of milk fatty acid (FA) according to the degree of saturation (i.e., saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA)). These findings indicated that the inclusion of GBP to 15% in replacement of beet pulp in the diet of dairy Saanen goats have no adverse effects on ruminal fermentation, blood metabolites and milk fatty acid.