متاآنالیز اثر روغن های گیاهی غنی از 18:2n-6 روی ترکیب اسیدهای چرب شیر در گاوهای شیرده

Background: including plant oils rich in unsaturated fatty acids in lactating cow diets can be used as a nutritional strategy to alter milk fatty acid composition for long-term human health.objectives: effects of dietary plant oils rich in 18:2n-6 (pola) on milk fatty acid (fa) composition in lactating cows, using meta-analysis and meta-regression approach were evaluated. methods: twenty experiments containing 27 comparisons between treatment and control groups, which met the selection criteria, were used. two levels of supplementing pola were evaluated: ? and > 30 g/kg diet dm. results: the pola, at both level, reduced relative proportions of 6:0–16:0, enhanced 18:0, cis (?9–12, and 15) and trans 18:1 (?6?14), 18:2n-6, cis-9,trans-11 cla, and trans-10,cis-12 cla, whereas approximately 20 g/kg dm oil supplementation had no effect on 4:0 and 18:3n-3 concentrations in milk fat. results of meta-regression showed that dietary 18:2n-6 content explained more than 55% of variation in results of 8:0–15:0. dietary total fa content differences, grain level of basal diets, and parity were the sources of heterogeneity in milk cis-9 18:1. milk trans-11 18:1 increased with increased dietary 18:2n-6 content and forage level of basal diets. safflower oil > sunflower oil > corn oil > soybean oil > cottonseed oil induced higher standardized mean difference of milk 18:2n-6, trans-10, cis-12 cla and 18:0 content.conclusions: feeding pola lowered milk saturated fa and increased trans, monounsaturated and polyunsaturated fa.