Bernhard Cathy J, Sharp Katharine G, Safranski Timothy J, Lamberson William R, Lucy Matthew C
Division of Animal Sciences, University of Missouri, Columbia, MO.
J Anim Sci. 2020 Nov 1;98(11). doi: 10.1093/jas/skaa352.
The primary objective was to assess the development of fetal gonads and measure the subsequent reproductive capacity of boars and gilts whose mother was either subjected to gestational heat stress (GHS) or thermoneutral (GTN; control) conditions during pregnancy. Gilts were subjected to either GHS (28 to 38 °C; 65% to 88% relative humidity [RH]; n = 30) or GTN (17 to 22 °C; 56% to 65% RH; n = 29) for the second month of gestation (a period that coincides with a critical window of gonadal development). A subset of GHS (n = 12) and GTN (n = 11) gilts was sacrificed immediately following treatment for the collection of pregnancy data. The remaining gilts (n = 18 GHS and n = 18 GTN) were allowed to farrow. Female offspring from the farrowed gilts were studied through puberty, first insemination, and early pregnancy when fetal tissues were again collected. During the treatment period, GHS gilts had greater (P < 0.001) rectal temperature and respiration rate at both measurement time points (morning and afternoon) compared with GTN gilts. When assessed at the end of the second month of gestation, the total number of viable fetuses did not differ (P > 0.10) for GHS vs. GTN. Likewise, the weight of the fetus, placenta, fetal testes, and fetal ovaries were similar (P > 0.10) for GHS and GTN pregnancies. There was a tendency for an effect of treatment (63.3 ± 2.3 vs. 70.1 ± 2.6; GHS vs. GTN; P < 0.073) on the number of oogonia per histological section in the fetal ovaries. There was no effect of treatment on the number of prespermatogonia per histological section in the fetal testis. For gilts farrowing after treatment, litter size, piglet birth weight, and weaning weight were similar (P > 0.10) for the GHS and GTN gilts. Testes collected from castrated GHS boars had fewer prespermatogonia per seminiferous tubule cross section (P < 0.049). Female offspring from the GHS (n = 30) or GTN (n = 37) sows reached puberty at a similar age, and their pregnancies (ninth week of gestation) had fewer corpora lutea (15.6 ± 0.5 vs. 17.1 ± 0.4; GHS vs. GTN; P < 0.038) but the number of fetuses was similar for GHS and GTN. In summary, compared with GTN, GHS during a critical window of gonadal development tended to reduce the number of oogonia in the fetal ovary, reduced the number of prespermatogonia in the neonatal testes, and reduced ovulation rate at first pregnancy in gilts.
主要目的是评估胎儿性腺的发育情况，并测量其母亲在孕期经历妊娠热应激（GHS）或处于热中性（GTN；对照）条件下的公猪和后备母猪随后的繁殖能力。在妊娠第二个月（这一时期与性腺发育的关键窗口期重合），将后备母猪置于GHS（28至38°C；相对湿度[RH]65%至88%；n = 30）或GTN（17至22°C；RH56%至65%；n = 29）环境中。治疗结束后，立即处死一部分GHS（n = 12）和GTN（n = 11）的后备母猪，以收集妊娠数据。其余的后备母猪（n = 18只GHS和n = 18只GTN）则任其产仔。对产仔后备母猪的雌性后代进行研究，直至其进入青春期、首次配种以及再次收集胎儿组织的早期妊娠阶段。在治疗期间，与GTN后备母猪相比，GHS后备母猪在两个测量时间点（上午和下午）的直肠温度和呼吸频率均更高（P < 0.001）。在妊娠第二个月末进行评估时，GHS组与GTN组的存活胎儿总数无差异（P > 0.10）。同样，GHS和GTN妊娠的胎儿、胎盘、胎儿睾丸和胎儿卵巢的重量相似（P > 0.10）。治疗对胎儿卵巢中每个组织学切片的卵原细胞数量有一定影响趋势（63.3 ± 2.3对70.1 ± 2.6；GHS对GTN；P < 0.073）。治疗对胎儿睾丸中每个组织学切片的精原细胞前体细胞数量没有影响。对于治疗后产仔的后备母猪，GHS和GTN后备母猪的窝产仔数、仔猪出生体重和断奶体重相似（P > 0.10）。从阉割的GHS公猪收集的睾丸中，每个生精小管横截面积的精原细胞前体细胞较少（P < 0.049）。GHS（n = 30）或GTN（n = 37）母猪的雌性后代在相似年龄达到青春期，且它们妊娠（妊娠第九周）时的黄体数量较少（15.6 ± 0.5对17.1 ± 0.4；GHS对GTN；P < 0.038），但GHS和GTN的胎儿数量相似。总之，与GTN相比，在性腺发育的关键窗口期的GHS倾向于减少胎儿卵巢中的卵原细胞数量，减少新生睾丸中的精原细胞前体细胞数量，并降低后备母猪首次妊娠时的排卵率。
