CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly 37380, France.
UEPEAT, INRAE, Nouzilly 37380, France.
Ecotoxicol Environ Saf. 2022 Aug;241:113741. doi: 10.1016/j.ecoenv.2022.113741. Epub 2022 Jun 6.
Glyphosate (Gly) is the active molecule of non-selective herbicides used in conventional agriculture. Some evidence shows that exposure to Glyphosate-Based Herbicides (GBH) can affect both male and female fertility in animal models. However, few data exist on birds that can be easily exposed through their cereal-based diet. To our knowledge, there are no current studies on the effects of chronic dietary exposure to GBH and the potential reversibility on the fertility and embryo development in chickens. In our protocol, hens (32 weeks-old) were exposed to GBH (47 mg kg-1/day-1 glyphosate equivalent corresponding to half of the No-Observed-Adverse-Effect-Level (NOAEL) as defined by European Food Safety Authority in birds, GBH group (GBH), n = 75) or not (Control group (CT), n = 75) for 6 weeks. Then, both CT and GBH groups were fed for 5 more weeks without GBH exposure. During these two periods, we investigated the consequences on the egg performance and quality, fertilization rate, embryo development, and viability of offspring. Despite the accumulation of Gly and its metabolite aminomethylphosphonic acid (AMPA) in the hen blood plasma, the body weight and laying rate were similar in GBH and CT animals. We observed from the 4th day of exposure an accumulation of Gly (but not AMPA) only in the yolk of the eggs produced by the exposed hens. After artificial insemination of the hens followed by eggs incubation, we showed a strong significant early embryonic mortality level in GBH compared to CT animals (78 ± 2 % vs 2.5 ± 0.3 %, p < 0.0001) with embryo death mainly occurring on the third day of incubation. By using computed tomography (CT) and magnetic resonance imaging (MRI) tools, we noted a significant delay in the embryo development of GBH survivors at 15 days with a reduction by half of the embryo volume and some disturbances in the calculated volumes of the embryonic annexes. At 20 days of incubation, we showed a reduction in the length of the tibia and in the volume of the soft tissues whereas the skeleton volume was increased in GBH chicks. The vast majority of these phenotypes disappeared two weeks after an arrest of the GBH maternal dietary exposure. Taken together, the dietary chronic exposure of broiler hens to GBH at a Gly equivalent concentration lower than NOAEL induces an accumulation of Gly in the egg yolk resulting in severe early embryonic mortality and a delayed embryonic development in survivors that were abolished two weeks after the end of GBH exposure.
草甘膦（Gly）是常规农业中使用的非选择性除草剂的活性分子。一些证据表明，暴露于草甘膦基除草剂（GBH）会影响动物模型中的男性和女性生育能力。然而，关于鸟类的资料很少，因为它们可以通过以谷物为基础的饮食轻易接触到草甘膦。据我们所知，目前尚无关于慢性饮食接触 GBH 及其对产蛋鸡和胚胎发育的潜在可逆性影响的研究。在我们的方案中，32 周龄的母鸡（n=75）暴露于 GBH（47mgkg-1/day-1 草甘膦当量，相当于欧洲食品安全局在鸟类中定义的无观察到不良作用水平（NOAEL）的一半，GBH 组（GBH））或不暴露（对照组（CT），n=75）6 周。然后，CT 和 GBH 两组在没有 GBH 暴露的情况下再喂养 5 周。在此期间，我们研究了对鸡蛋性能和质量、受精率、胚胎发育和后代活力的影响。尽管母鸡血液血浆中草甘膦及其代谢物氨甲基膦酸（AMPA）的积累，但暴露于 GBH 和 CT 动物中的体重和产蛋率相似。我们从暴露母鸡所产鸡蛋的第 4 天开始观察到仅在蛋黄中积累了草甘膦（而不是 AMPA）。在对母鸡进行人工授精并孵化鸡蛋后，我们发现暴露于 GBH 的母鸡的早期胚胎死亡率水平明显高于 CT 动物（78±2%对 2.5±0.3%，p<0.0001），胚胎死亡主要发生在孵化的第三天。通过使用计算机断层扫描（CT）和磁共振成像（MRI）工具，我们注意到 15 天时 GBH 幸存者的胚胎发育明显延迟，胚胎体积减少一半，一些胚胎附件的计算体积也受到干扰。在 20 天的孵化期，我们发现胫骨长度和软组织体积减少，而 GBH 小鸡的骨骼体积增加。这些表型中的绝大多数在 GBH 母体饮食暴露停止两周后消失。综上所述，肉鸡母鸡以低于 NOAEL 的草甘膦当量浓度进行慢性饮食接触会导致蛋黄中草甘膦的积累，从而导致严重的早期胚胎死亡率和幸存者的胚胎发育延迟，这种情况在 GBH 暴露停止两周后消失。
