Kasimanickam Ramanathan K, Kasimanickam Vanmathy R, Kumar Nishant, Reisenauer Conrad
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA.
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA; AARVEE Animal Biotech LLC, Corvallis, OR, 97333, USA.
Theriogenology. 2021 Mar 15;163:10-17. doi: 10.1016/j.theriogenology.2021.01.004. Epub 2021 Jan 13.
The objectives of this study were to investigate the effect of Day 7 embryo quality and subclinical endometritis (SCE) in repeat breeder recipient cows on morphometry of Day 16 embryo and to determine the association of %PMN, serum progesterone and Day 16 conceptus length. Holstein dairy cows that failed to conceive at least 3 times, (parity, 3 and 4; body condition score, 3 to 3.5 out of 5) with subclinical endometritis (n = 180; SCE, >6% PMN on endometrial cytology) or without subclinical endometritis (n = 180; No-SCE, ≤ 6% PMN) were selected. Cows in each group received single, frozen-thawed, quality 1 (n = 60), 2 (n = 60) and 3 (n = 60) embryos (compact morula or early blastocyst) on Day 7 post estrus in the uterine horn ipsilateral to the ovary containing a corpus luteum, using standard nonsurgical techniques. Only cows that expressed estrus (Select-Synch protocol) and with acceptable corpus luteum (≥1.5 cm in size) were included. Conceptuses were collected on Day 16 from all recipient cows by standard non-surgical uterine flushing technique, using an 18-g embryo collection catheter with Phosphate Buffered Saline (pH 7.4). Blood samples were collected on Day 16 to determine serum progesterone concentrations. After collection, conceptuses were weighed and measured, and were categorized as tubular (underdeveloped, 10-20 mm) or filamentous (normal, >25 mm). Between cows with SCE and No-SCE, mean (±SEM) width (1.68 ± 0.13 mm vs. 1.84 ± 0.16 mm), length (34.4 ± 9.6 mm vs. 55.8 ± 13.4 mm) and weight (22.3 ± 3.7 vs. 40.6 ± 6.4 mg) of Day 16 conceptuses differed (P < 0.05). The mean width (1.75 ± 0.19 mm vs. 1.81 ± 0.22 mm), length (57.7 ± 11.2 vs. 51.1 ± 13.6 mm) and weight (34.3 ± 6.4 vs. 38.5 ± 8.2 mg) of Day 16 embryo following transfer of Day 7 embryo quality grade 1 and grade 2 embryos were not different (P > 0.1), but both differed from the mean width (1.59 ± 0.11 mm), length (28.9 ± 9.7 mm) and weight (25.3 ± 4.6 mg) of Day 16 embryo from Day 7 embryo quality grade 3 (P < 0.05). Total percentage of embryos recovered differed between SCE and No-SCE groups (P < 0.05; 36.1 vs 48.9%). Total percentage of embryos recovered on Day 16 following transfer of grade 1 (53.3%) and 2 (44.2%) Day 7 embryos were greater (P < 0.05) compared with transfer of grade 3 embryos (29.2%) (P < 0.001). Total percentage of filamentous embryos recovered was lower for SCE cows compared with No-SCE cows (P < 0.01; 15.0 vs. 25.6%). Total percentage of tubular embryos recovered did not differ between SCE and No-SCE cows (P > 0.1; 21.1% vs. 22.8%). Filamentous embryo recovered for grade 3 was lower (P < 0.05) compared with grade 1 in both SCE (8.3 vs. 21.7%) and No-SCE groups (15.0 vs. 33.3%). The mean (±SEM) CL volume (cm; 11.8 ± 0.29 vs. 15.9 ± 0.31) and progesterone concentrations (ng/mL; 5.17 ± 1.8 vs. 8.2 ± 1.2) on Day 16 differed between SCE and No-SCE groups (P < 0.05) but not among Day 7 embryo grade groups (P > 0.1). The mean (±SEM) CL volume (cm; 15.6 ± 0.28 vs 12.1 ± 3.9) and serum progesterone concentrations (ng/mL; 8.6 ± 1.4 vs. 4.9 ± 1.9) on Day 16 differed (P < 0.05) between cows yielded filamentous and tubular embryos. When all cows were considered, multiple regression analysis showed that the %PMN (P < 0.0001), progesterone concentrations (P < 0.0001), embryo qulaity (P < 0.05) and %PMN by progesterone interactions (P < 0.0001) influenced the length of Day 16 conceptus. Among cows without subclinical endometritis, only progesterone concentrations (P < 0.0001) and among cows with subclinical endometritis, only %PMN (P < 0.04) influenced the length of Day 16 conceptus. Progesterone concentrations (P < 0.0001) influenced the length of Day 16 conceptus in cows that received embryo quality 1 and 2. Progesterone concentration by %PMN interaction (P < 0.05) also influenced the length of Day 16 conceptus in cows that received embryo quality 2. The %PMN (P = 0.05) influenced the length of Day 16 conceptus in cows that received embryo quality 3. In conclusion, poor quality Day 7 embryo and presence of SCE negatively influenced early embryo development between Days 7 and 16 of gestation probably by dysregulated embryo-maternal interactions due to lower progesterone, prompting loss of the conceptus in sub-optimal uterine environment.
本研究的目的是调查经产受体奶牛中第7天胚胎质量和亚临床子宫内膜炎（SCE）对第16天胚胎形态学的影响，并确定多形核白细胞百分比（%PMN）、血清孕酮和第16天孕体长度之间的关联。选择至少3次配种未受孕的荷斯坦奶牛（胎次为3和4；体况评分，5分制下为3至3.5分），其中患有亚临床子宫内膜炎的奶牛（n = 180；SCE，子宫内膜细胞学检查中PMN>6%）或未患亚临床子宫内膜炎的奶牛（n = 180；无SCE，PMN≤6%）。每组奶牛在发情后第7天，使用标准非手术技术，在含有黄体的卵巢同侧子宫角内移植单个、冻融后的1级（n = 60）、2级（n = 60）和3级（n = 60）胚胎（致密桑葚胚或早期囊胚）。仅纳入表现出发情（Select-Synch方案）且黄体合格（大小≥1.5 cm）的奶牛。在第16天，通过标准非手术子宫冲洗技术，使用带有磷酸盐缓冲盐水（pH 7.4）的18G胚胎采集导管，从所有受体奶牛中采集孕体。在第16天采集血样以测定血清孕酮浓度。采集后，对孕体进行称重和测量，并分为管状（发育不全，10 - 20 mm）或丝状（正常，>25 mm）。在患有SCE和无SCE的奶牛之间，第16天孕体的平均（±SEM）宽度（1.68±0.13 mm对1.84±0.16 mm）、长度（34.4±9.6 mm对55.8±13.4 mm）和重量（22.3±3.7对40.6±6.4 mg）存在差异（P < 0.05）。移植第7天1级和2级胚胎后，第16天胚胎的平均宽度（1.75±0.19 mm对1.81±0.22 mm）、长度（57.7±11.2对51.1±13.6 mm）和重量（34.3±6.4对38.5±8.2 mg）无差异（P > 0.1），但两者均与第7天3级胚胎的第16天胚胎平均宽度（1.59±0.11 mm）、长度（28.9±9.7 mm）和重量（25.3±4.6 mg）不同（P < 0.05）。SCE组和无SCE组回收胚胎的总百分比存在差异（P < 0.05；36.1对48.9%）。与移植3级胚胎（成功率29.2%）相比，移植1级（成功率53.3%）和2级（成功率44.2%）第7天胚胎后，第16天回收胚胎的总百分比更高（P < 0.05）（P < 0.001）。与无SCE奶牛相比，SCE奶牛回收的丝状胚胎总百分比更低（P < 0.01；15.0对25.6%）。SCE和无SCE奶牛回收的管状胚胎总百分比无差异（P > 0.1；21.1%对22.8%）。在SCE组（8.3对21.7%）和无SCE组（15.0对33.3%）中，3级胚胎回收的丝状胚胎均低于1级（P < 0.05）。第16天，SCE组和无SCE组的平均（±SEM）黄体体积（cm；11.8±0.29对15.9±0.31）和孕酮浓度（ng/mL；5.17±1.8对8.2±1.2）存在差异（P < 0.05），但在第7天胚胎等级组之间无差异（P > 0.1）。第16天，产出丝状和管状胚胎的奶牛之间，平均（±SEM）黄体体积（cm；15.6±0.28对12.1±3.9）和血清孕酮浓度（ng/mL；8.6±1.4对4.9±1.9）存在差异（P < 0.05）。当考虑所有奶牛时，多元回归分析表明，%PMN（P < 0.0001）、孕酮浓度（P < 0.0001）、胚胎质量（P < 0.05）以及%PMN与孕酮的相互作用（P < 0.0001）影响第16天孕体的长度。在无亚临床子宫内膜炎的奶牛中，仅孕酮浓度（P < 0.0001）有影响；在患有亚临床子宫内膜炎的奶牛中，仅%PMN（P < 0.04）有影响。孕酮浓度（P < 0.0001）影响接受1级和2级胚胎质量奶牛的第16天孕体长度。孕酮浓度与%PMN的相互作用（P < 0.05）也影响接受2级胚胎质量奶牛的第16天孕体长度。%PMN（P = 0.05）影响接受3级胚胎质量奶牛的第16天孕体长度。总之，第7天胚胎质量差和SCE的存在可能通过孕酮水平降低导致胚胎 -母体相互作用失调，对妊娠第7天至16天的早期胚胎发育产生负面影响，促使孕体在子宫环境欠佳时丢失。
