engleski

Effect of parity on serum nonesterified fatty acid, HDL- cholesterol and apolipoprotein A- I levels and paraoxonase- 1 activity in Holstein cows during the transition period

The transition from the non-lactating to lactating stage causes nutritional and metabolic stress in dairy cows. Parity is an important factor that could influence the ability of cows to cope with demanding energy and metabolic conditions during the transition period. The aim of this study was to assess the effect of parity on lipid metabolism, apolipoprotein A- I (ApoA- I) and paraoxonase-1 (PON1) activity in transition dairy cows. The study included 24 dairy cows assigned to two groups according to the number of lactations: primiparous (n = 12) and multiparous cows (n = 12). Blood samples were collected on days −30, −10, −2, 0, 5, 12, 19, 26 and 60, relative to calving. Serum nonesterified fatty acid (NEFA) concentration was measured using the Randox NEFA kit on the biochemical analyzer SABA 18 (AMS, Rome, Italy), while high-density lipoprotein- cholesterol (HDL-C) concentration was assayed by the method based on selective inhibition of non- HDL fractions by means of polyanions on Beckman Coulter AU 680 (Beckman Coulter Biomedical Ltd., Ireland). ApoA-I was assayed by the bovine ELISA kit (NovaTeinBio, USA). PON1 activity was measured by the spectrophotometric assay with paraoxon as a substrate on Beckman Coulter AU 680. Statistical analysis was performed using the SAS 9.3 So􀁛ware. There were no significant differences in NEFA, HDL- C, ApoA- I and PON1 between primiparous and multiparous cows during the transition period (p > 0.05). Nevertheless, in all cows, PON1 and HDL-C were significantly lower (p < 0.05) at parturition, while NEFA was significantly elevated at calving (p < 0.05). Results indicated that lipid metabolism, ApoA-I and PON1 activity were not influenced by parity. However, NEFA, HDL- C and PON1 were greatly influence by the transition period.

parity; serum nonesterified fatty acid; HDL-cholesterol and apolipoprotein A-I; paraoxonase-1; Holstein cows; transition period

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