Camacho L E, Lemley C O, Dorsam S T, Swanson K C, Vonnahme K A
Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, United States.
Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, United States.
Theriogenology. 2018 Aug;116:1-11. doi: 10.1016/j.theriogenology.2018.04.013. Epub 2018 Apr 24.
The objectives were to examine the effects of maternal nutrient restriction followed by realimentation during early to mid-gestation on placental development and uterine and umbilical hemodynamics in the beef cow. On day 30 of pregnancy, multiparous, non-lactating beef cows (620.5 ± 11.3 kg) were assigned to 1 of 2 dietary treatments: control (C; 100% National Research Council [NRC] recommendations; n = 18) and restricted (R; 60% NRC; n = 30). On day 85, cows were slaughtered (C, n = 6; R, n = 6), remained on control (CC; n = 12) and restricted (RR; n = 12), or were realimented to control (RC; n = 11). On day 140, cows were slaughtered (CC, n = 6; RR, n = 6; RC, n = 5), remained on control (CCC, n = 6; RCC, n = 5), or were realimented to control (RRC, n = 6). On day 254, all remaining cows were slaughtered. Heart rate and umbilical and uterine hemodynamics [blood flow, resistance index (RI), and pulsatility index (PI)] were determined via Doppler ultrasonography. As expected umbilical blood flow increased and fetal heart rate decreased as gestation advanced. Umbilical PI in RRC cows was less (P = 0.01) compared to RCC and CCC. During late gestation, RCC cows had greater (P = 0.02) ipsilateral and total uterine blood flow vs. CCC and RRC. There was an increase in the number and weight of placentomes from R cows (P ≤ 0.02) compared to C cows (i.e. day 85). There were more placentomes (P = 0.03) in RR vs. CC and RC cows, but placentome weight was not affected (P = 0.18) by maternal dietary treatment at day 140. Maternal nutrient restriction during early to mid-gestation increased the weight (by day 85) and number (day 85 and 140) of placentomes, and did not reduce fetal weight compared to control cows. A longer realimentation period may enhance uterine blood flow and individual placentome size during later gestation, which may compensate for reduced nutrients experienced early in gestation.
本研究旨在探讨妊娠早期至中期母体营养限制后再恢复营养对肉牛胎盘发育、子宫及脐部血流动力学的影响。妊娠第30天，将经产非泌乳肉牛（体重620.5±11.3千克）分为2种日粮处理组：对照组（C；100%美国国家研究委员会 [NRC] 推荐量；n = 18）和限制组（R；60% NRC；n = 30）。第85天，屠宰部分母牛（C组n = 6；R组n = 6），其余母牛继续维持对照（CC组；n = 12）和限制（RR组；n = 12）饲养，或恢复至对照水平（RC组；n = 11）。第140天，屠宰部分母牛（CC组n = 6；RR组n = 6；RC组n = 5），其余母牛继续维持对照（CCC组；n = 6；RCC组；n = 5），或恢复至对照水平（RRC组；n = 6）。第254天，屠宰所有剩余母牛。通过多普勒超声测定心率以及脐部和子宫血流动力学指标[血流量、阻力指数（RI）和搏动指数（PI）]。正如预期，随着妊娠进展，脐血流量增加，胎儿心率下降。与RCC组和CCC组相比，RRC组母牛的脐部PI较低（P = 0.01）。在妊娠后期，与CCC组和RRC组相比，RCC组母牛同侧和子宫总血流量更大（P = 0.02）。与C组母牛（即第85天）相比，R组母牛胎盘小叶的数量和重量增加（P≤0.02）。与CC组和RC组相比，RR组母牛的胎盘小叶数量更多（P = 0.03），但在第140天，母体日粮处理对胎盘小叶重量无影响（P = 0.18）。与对照母牛相比，妊娠早期至中期母体营养限制增加了胎盘小叶的重量（至第85天）和数量（第85天和第140天），且未降低胎儿体重。较长的恢复营养期可能会增加妊娠后期的子宫血流量和单个胎盘小叶大小，这可能弥补妊娠早期所经历的营养减少。
