Abstract

The effects of sub-clinical endometritis (scEndo) on ovarian follicular activity in pasture-fed dairy cows were determined. The uterine-health status of lactating dairy cows (n = 169) was assessed on day (D) 21 (± 3 days) postpartum by Metricheck. In a sub-population (n = 47; 32 clean, 15 scEndo), Metricheck assessment was repeated on D42 and uterine cytology undertaken on D21 and D42 [scEndo = polymorphicnuclear (PMN) cells >18%]. Follicular activity was assessed by ultrasound on D42 and D63. Metricheck evaluation revealed that the proportion of cows with scEndo was 15/169 (8.9%) and 4/47 (8.5%) on D21 and D42 respectively. Irrespective of the method used to determine scEndo, dominant (P <0.001) but not subordinate (P >0.1) follicles were larger and grew faster on D63 than on D42. Based on the D21 Metricheck but not the %PMN classification, dominant follicles of scEndo cows were larger and grew faster (P = 0.02) than those in clean cows. No overall effect of uterine status was found on the subordinate follicles, although these tended (P = 0.06) to be larger on D63 than on D42 but only in clean cows. Thus early postpartum scEndo appears to modulate the subsequent size of the dominant follicle. However, it remains to be determined whether this affects the subsequent fertility of these cows.

PJ, Back, AM Ledgard, S Beaumont, MC Berg, AJ Peterson, KP McNatty, and MP Green

Proceedings of the New Zealand Society of Animal Production, Volume 69, Christchurch, 32-36, 2009