Influence of endometritis on the follicular dynamics, recovery, quality, gene expression, nuclear maturation and in-vitro developmental competence of oocytes in Sahiwal cattle.

Abstract

Uterine infections often lead to culling of valuable animals from a herd, resulting in genetic drain. The genetic potential of problematic females could be harvested by in-vitro embryo production. The objective of this study was to evaluate the effect of clinical endometritis on follicular dynamics, recovery, quality, gene expression, nuclear maturation and in-vitro developmental competence of oocytes in Sahiwal cattle. The B-mode ultrasonography was performed to examine the uterus for the presence of pus. Based on the history and reproductive examination of cows, a total of twelve (n=12) Sahiwal cattle were selected for the experiment: (1) healthy group (n=6) and (2) clinical endometritis group (n=6). The 1st ovum pick-up (OPU) was conducted on day 165 postpartum. The collected cumulus oocytes complexes (COCs) were graded into A, B, C and D grades depending on the number of layers of cumulus cells and homogeneous nature of cytoplasm. Nuclear maturation was assessed by staining the oocytes with Hoechst 33,342. The results revealed that the number of medium-sized follicle (1.3±0.1 versus 0.6±0.1) and total number of follicles (9.1±0.7 versus 6.6±0.7) were higher (p<.05) in the healthy group as compared to clinical endometritis group, respectively. Similarly, the number of oocytes recovered (5.0±0.4 versus 2.8±0.4), oocytes with grade A, B and C (2.9±0.3 versus 1.5±0.3), proportion of oocytes with grade A or B (33±0.0 versus 20±0.1) and nuclear maturation (68±0.1 versus 55±0.1) were also higher (p<.05) in the healthy group as compared to clinical endometritis group, respectively. Perhaps, cleavage rate (55.1±0.1 versus 46.2±0.1) and blastocyst rate (29.7±0.0 versus 26.3±0.1) did not differ (p>.05) between the groups. Likewise, the expression level of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) in immature oocytes did not differ (p>.05) between both the groups. In conclusion, clinical endometritis has a negative effect on follicular dynamics, oocyte recovery, oocyte quality and nuclear maturation; furthermore, the developmental competence of COCs is not compromised by it.