Effect of conjugated linoleic acid supplementation during the transition period on plasma metabolites and productive and reproductive performances in dairy cows

The objective of this study was to determine the effects of dietary conjugated linoleic acid (CIA) supplementation during the transition period on plasma metabolites and productive and reproductive performance in dairy cows. Seventy five multiparous Holstein cows approximately 3 weeks before expected calving date were randomly assigned to 1 of 4 diets containing: (1) CLA21 (n = 18), rumen protected CLA (75 g/h/d, Lutrell Pure, BASF, Ludwigshafen, Germany) from 21 d before parturition (dbp) to 21 d postpartum (dpp); (2) CLA42 (n = 19), rumen protected CIA from 21 dbp to 42 dpp; (3) P021 (n = 18), palm oil (75 g/h/d) from 21 dbp to 21 dpp; or (4) P042 (n = 20), palm oil from 21 dbp to 42 dpp. Daily milk yield and body condition score (BCS) at calving and 42 dpp were recorded. Milk fat, protein and lactose were determined weekly. Blood samples were collected from 8 cows in each dietary group at 20.2 +/- 3.2 (mean SEM), 0, 10, 21 and 42 d relative to calving (day 0) to determine plasma concentration of glucose, cholesterol, triglyceride, high density lipoprotein (HDL), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and insulin. Milk yield was greater in cows fed diets supplemented with CIA compared to those fed PO diets, conversely overall milk fat content and fat yield was lower in cows fed CIA compared to those fed diets supplemented with PO. There were no differences among diets for dry matter intake (DMI). Cows in CLA21and those in PO42 dietary treatments had the least and greatest BCS loss, respectively from calving until 42 dpp. Plasma concentrations of glucose and cholesterol were greater in CIA fed cows compared with PO fed cows. Plasma NEFA and BHBA were lower in PO21 and CLA21 cows than in PO42 and CLA42 cows. However, dietary treatment had no effect (P >= 0.05) on plasma concentration of triglyceride, HDL, SGOT, SGPT and insulin. In addition, reproductive performance did not differ among dietary groups. In summary, feeding CLA during transition period decreased milk fat percentage, BCS loss and increased plasma concentrations of glucose and cholesterol, and milk yield. Extending supplementation of either CLA or PO from 21 to 42 dpp increased plasma concentrations of BHBA and NEFA, but did not alter milk composition and yield. Reproductive performance of dairy cows did not differ among dietary treatments. (C) 2016 Elsevier B.V. All rights reserved.