By Scout Nelson
Research from South Dakota State University has revealed that limited exposure to mild cold stress during pregnancy could help improve lamb birth weights and early growth performance. The findings offer sheep producers a simple management practice that may enhance flock productivity without adding significant costs.
Scientists investigated the effects of shearing pregnant ewes earlier than normal during gestation. In many sheep operations, ewes carrying spring lambs are commonly shorn later in pregnancy to improve cleanliness and ease management during lambing. However, researchers wanted to understand whether exposing ewes to mild cold conditions earlier in pregnancy could influence fetal development.
“It’s always been known that heat stress, in any pregnant animal, is going to cause problems for the developing fetus, so I wondered what cold stress does,” said Alex Vasquez-Hidalgo, Ph.D., an assistant professor in the SDSU Department of Veterinary and Biomedical Sciences. “It appears that some cold stress, not extreme of course, but some cold stress is beneficial for the physiology of the pregnant ewe.”
The study focused on ewes that were shorn around day 50 of gestation. Researchers compared them with ewes that were not shorn during the same period. The timing was carefully selected because it coincides with an important stage of placental growth and development. The placenta plays a critical role in transporting nutrients and oxygen from the mother to the growing fetus.
From day 50 to day 110 of pregnancy, researchers monitored the animals using ultrasound technology. They measured fetal growth, placental development, and umbilical blood flow to better understand how the developing lambs responded to the environmental changes experienced by their mothers.
The study found that lambs born to ewes exposed to limited cold stress through early shearing were larger and heavier at birth. The effect was especially noticeable among twin and triplet lambs. Researchers also observed greater umbilical blood flow in these pregnancies, suggesting improved nutrient delivery to developing fetuses.
Birth weight is an important factor in sheep production because heavier lambs generally have a better chance of survival during the early stages of life. Producers often aim to improve birth weights within healthy limits because stronger lambs are more likely to thrive and reach important growth milestones.
The benefits observed in the study extended beyond birth. Lambs from the early-shorn ewes remained heavier later in life and recorded greater weights at weaning. These results suggest that the effects of mild cold exposure during pregnancy may continue to influence animal growth well after birth.
Researchers believe that when pregnant ewes experience moderate cold conditions, their bodies respond by adapting to the environment. This response may send important physiological signals to the developing fetus, preparing it for life in a cooler climate. These adaptations could contribute to improved growth and development before birth.
The findings indicate that controlled exposure to mild cold stress may be a valuable management tool for sheep producers, particularly those managing flocks with multiple births. Since twin and triplet lambs often face greater challenges at birth, improvements in birth weight and early growth could have meaningful production benefits.
Importantly, the research does not suggest exposing animals to severe or harmful cold conditions. Instead, the study highlights the potential benefits of carefully managed and limited cold exposure during specific stages of pregnancy. Animal welfare remains a critical consideration in any livestock management practice.
Researchers are continuing to explore the biological mechanisms behind these findings. Future studies will examine whether lambs born to early-shorn ewes respond differently to temperature conditions later in life and whether they gain additional survival or growth advantages as a result. Scientists are also investigating whether the benefits come solely from cold exposure or if the act of shearing itself contributes to the positive outcomes.
The research adds to growing knowledge about how environmental conditions during pregnancy can influence livestock development and performance. By better understanding these relationships, producers may be able to improve animal health, productivity, and profitability through simple management decisions.
For sheep producers looking for practical ways to support lamb growth and survival, early shearing during pregnancy may offer a promising option. While additional research is underway, the findings suggest that a carefully timed management strategy could help produce healthier lambs and improve overall flock performance.
Photo Credit: istock-heebyj
Categories: South Dakota, Livestock, Goats & Sheep