艾琳·基廷和贾森·罗斯，助理教授，动物科学，季节性不孕成本生产商美国最重要的猪状态的估计，每年约60亿美元。在全国范围内，养猪业的损失约为420亿美元。
，“基廷说：”经过了漫长，炎热的夏天，猪有问题，要么怀孕或维持妊娠。
其他ISU科学家们正在研究猪的热应激。这是暴露在生殖生理和卵巢功能障碍，引发了她的兴趣在研究可能的胰岛素的作用，研究和基廷的知识。
支持这项研究是由爱荷华州的猪肉生产者协会的资助。
基廷知道母猪的热应力研究中有高水平的胰岛素。她也知道，高循环胰岛素水平和不孕不育的问题，并维持妊娠是常见的肥胖妇女。
“当妇女患有肥胖症，他们有生育问题，”基廷说。“肥胖的女性不排卵非常好，甚至当他们的医生诱导排卵，他们的鸡蛋是质量不是很好。在女性中，肥胖与高循环胰岛素水平。“
猪热应激时，他们吃的并不多。不过，即使他们是不是吃，热应力导致的循环胰岛素升高。
“这是正常相反的任何动物，”她说。“通常情况下，动物吃的时候，你有一个高的血糖水平，然后释放胰岛素，血糖水平恢复正常。因此，通常胰岛素上升后，你已经吃了。但这些热应激抑制动物的采食量。“
基廷称这是一个“奇怪的生理现象”，她是兴趣探索，因为季节性不孕不育是这样一个巨大的经济成本，爱荷华生产者。
她相信，他们可能是第一次科学家研究一个潜在的季节性不孕不育的猪胰岛素链接。
$ 53,000一年IPPA授予允许基廷和罗斯进行研究猪的卵巢在国际滑联的热应力研究。
早期的研究结果表明，有可能是变化的途径，使雌激素在卵巢的热应激的猪，它可以发挥作用的季节性不孕。
“如果你不具有雌激素的释放，你不排卵。在猪，还有什么需要它们来显示他们是在热和人工授精。产妇确认怀孕的雌激素也有必要。因此，当一头猪有一个受精卵，雌激素是什么信号猪的身体增长提供支持，而不是拒绝外国侵略者的鸡蛋。基廷说：“我们想知道发生了什么事在猪体内的雌激素水平和季节性不孕不育的问题。
基廷希望该会资助的研究过程中，他们可能会开始确定治疗或干预策略。将需要更多的研究，包括进行试验之前，任何建议可以向生产者。
“在未来，我们希望能够做一些更大规模的试验，用人缓解策略，是适用于爱荷华州。我们希望能够识别的东西，可以有所作为，做一些事情，帮助经济。如果我们能想出一种治疗或干预策略，它可以节省很多钱，爱荷华州的生产者和周围的人在美国和国外。这是一个全球性的问题，“她说。
Animal scientists at Iowa State University, in Ames, IA, United States are searching for reasons and solutions for seasonal infertility in sows, including what may be the first scientific study of insulin's possible role in the problem.
Aileen Keating and Jason Ross, assistant professors of animal science, estimate that seasonal infertility costs producers the US most important swine state about $60 million a year.Nationally, the losses to the swine industry are approximately $420 million annually.
“After a long, hot summer, pigs have problems with either getting pregnant or maintaining a pregnancy,” said Keating.
Other ISU scientists are studying heat stress in pigs.It was exposure to that study and Keating's knowledge of reproductive physiology and ovarian dysfunction that triggered her interest in studying the possible role of insulin.
The research is supported by a grant from the Iowa Pork Producers Association.
Keating knew that the sows in the heat-stress study had high levels of insulin.She also knew that high circulating insulin levels and problems with infertility and maintaining a pregnancy are common among obese women.
“When women are obese, they have problems with fertility,” Keating said.“Obese women don't ovulate very well and even when they are medically induced to ovulate, their eggs are not very good quality.In women, obesity is associated with high circulating insulin levels.”
When pigs are heat-stressed, they don't eat much.But even though they aren't eating, heat stress causes elevations in circulating insulin.
“That's the opposite of normal in any animal,” she said.“Normally, when animals eat, you have a high level of blood glucose and then insulin is released to get blood glucose levels back to normal.So usually insulin goes up after you've eaten.But these heat-stressed animals have suppressed feed intake.”
Keating called it a “weird physiological phenomenon” that she was interested in exploring because seasonal infertility is such a huge economic cost to Iowa producers.
She believes they may be the first scientists to study a potential insulin link to seasonal infertility in swine.
The $53,000 one-year IPPA grant is allowing Keating and Ross to conduct research on the ovaries of the pigs in ISU's heat stress studies.
Early findings indicate that there may be changes to the pathway that makes oestrogen in the ovary of a heat-stressed pig, which could play a role in seasonal infertility.
“If you don't have an estrogen release, you don't have ovulation.In pigs, it's also what's needed for them to display they are in heat and to be inseminated.Estrogen is also necessary for maternal recognition of pregnancy.So when a pig has a fertilised egg, estrogen is what signals to the pig's body to provide support for growth and not reject the egg as a foreign invader.We want to know more about what's happening with estrogen levels in pigs and the seasonal infertility issue,” said Keating.
Keating is hopeful that during the IPPA-funded study they may begin to identify therapies or intervention strategies.Additional research will be needed, including conducting trials, before any recommendations can be made to producers.
“In the future, we would like to be able to do some larger trials employing mitigation strategies that are applicable to Iowa.We would like to be able to identify something that could make a difference and do something that helps the economy.If we can come up with a kind of therapy or intervention strategy, it could save a lot of money for Iowa producers and those around the US and abroad.This is a global problem,” she said.