Heat stress in sows and its effects on farrowing duration

Heat stress in sows affects the duration of farrowing. In fact, it can affect sows’ entire reproductive cycle (Lucy & Sanfranski, 2017). Negative effects such as fewer embryos and shorter gestation duration can be observed when associated with the mother’s gestation period. Furthermore, at the end of pregnancy, heat stress can increase the duration of farrowing and significantly result in an increased number of stillborn piglets.

When temperatures rise above the thermal comfort zone for sows, typically around 18-22°C (64-72°F), they experience physiological stress. This stress disrupts hormonal balances crucial for reproductive processes. Changes in the hormonal cycle lead to irregular estrus cycles, reduced conception rates, and increased incidences of early embryonic loss.

For example, Munns et al. (2016) evaluated the productive indicators of femalesunder heat stress conditions (maximum of 25 ºC) at the end of pregnancy. Females housed in an ideal environment (maximum of 20 ºC). The results of this study showed that the sows under the control treatment had a shorter farrowing period than those under heat stress (412 vs. 580 min).

Other consequences

Heat stress affects the duration of the farrowing cycle in sows. They may exhibit prolonged labour, leading to higher rates of stillbirths and compromised piglet viability. Furthermore, sows under heat stress often reduce feed intake to lower metabolic heat production, resulting in poor body condition and insufficient milk production, adversely affecting piglet growth and survival.

That prolonged farrowing duration has adverse effects on both sows and piglets. Long farrowing can, for example, compromise the piglets’ intake of quality colostrum since the concentration of immunoglobulins significantly decreases after the first 6 hours of the birth of the first piglet (Adi et al., 2022). For those reasons, providing sows with heat comfort is essential.

Managing heat stress through cooling systems, proper ventilation, and nutritional strategies is essential to maintain the health and productivity of sows, ensuring successful farrowing cycles and overall herd performance.