Impairment of fertility
- Returned delay to cyclic activity due to reduced GnRH and LH pulsatility, which is essential for follicular development and ovulation 59
- follicles developing during NEB showed a reduced sensitivity to circulating LH leading to reduced estradiol production 59, 60, 61
- an increased concentration of BHBA in follicular fluid impaired the developmental potential of oocytes, thus coupled with poor CL formation and function increasing the risk of embryo death 62, 63
- SCK and clinical ketosis are associated with reduced intensity and duration of estrus activity 64, 65
- Cows in NEB with increased blood BHBA in early lactation showed an increased calving to first service interval of 10 d compared to nonaffected counterparts 61
Since elevated BHBA during NEB occurs mostly concomitantly with other metabolic and endocrine changes (e.g. re-initiation of cyclic ovarian activity) some of the effects observed may not be exclusively ascribed to ketone bodies 48.