Effect of pomegranate seed oil as a source of conjugated linolenic acid on performance and milk fatty acid profile of dairy goats

Abstract

The objective of this experiment was to investigate the effects of dietary pomegranate seed oil and linseed oil on lactational performance, ruminal fermentation parameters, nutrients digestibility and milk fatty acid (FA) content, particularly conjugated linoleic acid (CLA), conjugated linolenic acid (CLnA) and vaccenic acid (VA) of dairy goats. Twenty-four Mahabadi goats in mid lactation were assigned to three dietary treatments: 1- control diet, basal diet without added oil (CON), 2- diet supplemented with 25g/kg pomegranate seed oil (PSO), and 3- diet supplemented with 25g/kg linseed oil (LSO), on a dry matter (DM) basis. Feed intake, milk yield and 4% fat-corrected milk yield were similar for goats fed different diets. Milk fat concentration (P<0.01) and fat/ protein ratio (P<0.0001) of goats fed PSO and LSO diets increased, while milk protein, lactose and solid not fat concentrations were not affected by diets (P>0.05). Addition of vegetable oils to diet had no effect on apparent digestibility of nutrients and ruminal fermentation parameters (P>0.05). The proportions of VA (P<0.001) and C18:1 (trans-9+trans-10, P<0.01) acids were increased in milk fat from goats fed PSO and LSO diets compared with goats fed CON diet. The concentration of cis-9, trans-11 CLA (rumenic acid) increased with oil supplements (P<0.0001) and was greatest for goats fed PSO diet. Compared with CON and LSO diets, feeding PSO diet increased cis-9, trans-11, cis-13 C18:3 CLnA (punicic acid) in milk fat (P<0.0001). The concentrations of monounsaturated fatty acids (MUFA; P<0.05), polyunsaturated fatty acids (PUFA; P<0.0001) and n-3PUFA (P<0.0001) increased and n-6/n-3 PUFA ratio (P<0.0001) decreased with oil supplemented diets. In conclusion, feeding PSO and LSO to dairy goats was a useful way to increase milk fat, CLA, and VA content of milk and to reduce the n-6/n-3 PUFA ratio without negative effects on intake, milk yield, and nutrients digestibility.