Milk fatty acid composition, rumen microbial population and animal performance in response to diets rich in linoleic acid supplemented with

Abstract

Context Rumen biohydrogenation is an important way to produce conjugated linoleic acid (CLA), especially the rumenic acid isomer. However, CLA is principally synthesised endogenously in lactating mammals by delta 9-desaturase in breast tissue. Aims The aim of the study was to evaluate milk fatty acid profile, rumen microbial population and animal performance in response to diets containing sunflower oil either supplemented with or without flavonoids and essential oils from Piper betle L. powder (PP) in dairy goats. Method Twelve multiparous Saanen goats (42 ± 1.00 kg; mean ± s.d.) were randomly assigned to two treatment groups in an experiment that lasted for 6 weeks. The two experimental diets formulated as total mixed ration were: control (CTH) diet (containing 0% PP) and DPB diet (CTH diet containing 1.3% PP on a dry-matter basis). Key results Inclusion of flavonoids and essential oils from PP in the diet (DPB) did not affect dry-matter intake but resulted in a greater milk yield and altered the composition of milk. Compared with the control diet (CTH), the DPB diet decreased the saturated fatty acid concentration and increased the unsaturated fatty acid concentration in milk. Inclusion of PP decreased the C18:0 production (P < 0.05), resulting in higher C18:1 trans11 and C18:2 cis9 trans11 (P < 0.05) concentrations. Overall, DPB diet increased the total CLA by 1.5-fold, from 1.77 to 2.62 g/100 g fatty acid. The desaturase rate (except desaturase for carbon 18, P < 0.05), and atherogenic and thrombogenic indices were not affected by inclusion of PP in the DPB diet. Moreover, the DPB diet escalated total volatile fatty acid production and altered the volatile fatty acid profile. Compared with goats fed with CTH diet, PP supplementation increased the presence of ruminal Butyrivibrio fibrisolvens by ~5-fold, but the presence of B. proteoclasticus decreased to about 1/11 of the control. Conclusions The use of sunflower oil at 17.6 g/kg diet and inclusion of a practical dose of flavonoids and essential oils from Piper betle L. leaves in the diet of dairy goats can be an efficient method to improve milk yield and milk composition, including increasing the CLA concentration of milk. Implications These results constitute an alternative strategy to improve milk quality, without negatively affecting animal performance.