Effect of pre‐ and post‐partum supplementation with lipid‐encapsulated conjugated linoleic acid on milk yield and metabolic status in multiparous high‐producing dairy cows

Summary We evaluated the lactation performance, liver lipid content and plasma metabolites indicating the energy balance of dairy cows supplemented with conjugated linoleic acid ( CLA ) pre‐ and post‐partum ( PP ) vs. only PP . A total of 60 cows were divided into three groups ( n  = 20). Daily diet of cows was supplemented with 14 g of CLA (7 g cis‐9, trans‐11 and 7 g trans‐10, cis‐12 isomers) from week 3 before the expected date of calving (group CLA 1), or from the day of calving (group CLA 2) until 77–91 days PP . Control cows were fed an isocaloric, isonitrogenous and isolipidic diet without CLA . Between week 3 and week 6 PP , the milk yield of cows in both CLA ‐treated groups was approximately 4.5 kg higher (p < 0.05) than in control. Milk fat concentrations decreased from week 3 and were lower in both CLA groups than in control (p < 0.01). Body condition score loss was lower (p < 0.05) in the CLA 1 than in the control group on week 5 PP . By week 11 PP , the body condition of both CLA 1 and CLA 2 groups exceeded that of control. Plasma non‐esterified fatty acid was lower in CLA 1 compared to CLA 2 and control during the early PP period (p < 0.05), while this difference faded away by the late PP period. Beta‐hydroxybutyrate ( BHBA ) increased rapidly in all groups following calving. In CLA 1 group, it began to decrease sooner than in CLA 2 and control. The prevalence of subclinical ketosis ( BHBA  > 1.2 m m ) was lower in CLA 1 group than in CLA 2 and control (p < 0.05). Liver biopsy analyses showed that CLA 1 treatment decreased (p < 0.05) the total lipid content of liver compared to control at week 5 after calving. Our results show that CLA supplementation is more efficient in alleviating body mass mobilization and decreasing the incidence of subclinical ketosis when applied as early as 3 weeks before calving than started feeding after calving.