Authors: FAEZEH PISHVAEI, MARYAM KARIMI DEHKORDI, MOHAMMAD REZA NAZEM

Abstract: This study aimed to investigate the effect of hyperketonemia on estrogen, progesterone and ovarian follicle size during postpartum as well as on pregnancy rate at first insemination. Regarding this, 90 Holstein cows were selected from one of the industrial dairy farms in Isfahan province, Iran. Estrus synchronization was routinely applied to all cows using the Ovsynch method. The blood sample of the cows was taken two times. The first blood sample was taken in 7-14 days after calving; to measure betahydroxybutyrate (BHBA), and the second sample was taken at the first insemination to measure the 17-ß oestradiol and progesterone hormones. The pregnancy status was recorded at the first insemination. T-test analysis was used to evaluate the effects of hyperketonemia on the concentration of steroid hormones and pregnancy rate at first insemination. 4.4% of cows (4 of 90) had subclinical ketosis (SCK) (BHBA greater than 1000 μmol/L). Results showed that cows with BHBA levels greater than 600 μmol/L in 7-14 days of postpartum had lower 17-ß oestradiol levels (p = 0.04) and higher progesterone levels (p = 0.06) at the time of insemination. Pregnant cows also had significantly lower serum BHBA and higher 17-ß oestradiol levels than nonpregnant cows at first insemination. The levels of BHBA, oestradiol, and progesterone were not significantly different in cows with different ovulation follicle sizes (p > 0.05). However, the level of BHBA was lower in cows that exhibit symptoms of estrus at the time of insemination (p = 0.07). 17-ß oestradiol levels were higher and progesterone levels were lower in cows with estrus symptoms with p = 0.07 and p = 0.01, respectively. The present study confirms that higher ketone bodies have negative effects on 17-ß oestradiol level and fertility. Also it appears that postpartum return to estrus is associated with high concentrations of 17-ß oestradiol and a low concentration of BHBA in early lactation.

Keywords: Beta-hydroxybutyrate (BHBA), estrogen, progesterone, pregnancy at first insemination, follicular size, estrous symptoms

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