This topic is not a completely new one but there does seem to be some renewed interest in investigating the impact of late gestation anemia on farrowing outcomes. The thinking is that without adequate oxygen transport you can’t burn the energy that is required for the intense work involved in farrowing. These Australian and Thai researchers wanted to revisit the effects of sow anaemia on farrowing outcomes. A total of 1136 sows of various parities from commercial swine farms in Thailand were included in the study. Sows were enrolled in the study based on their blood hemoglobin (Hb) concentration. Blood hemoglobin was measured somewhere between 109 to 113 days of gestation. A photometric method categorized sows as either Hb < 10 g/dL = anemic or Hb ≥ 10 g/dL = normal. The researchers recorded farrowing duration, time from last pig to placental expulsion, litter size born, colostrum quality (Brix percentage), circulating concentrations of glucose and cholesterol, prepartum progesterone levels, and backfat thickness.
The researchers found the following:
- Anemic sows (n = 515) exhibited longer farrowing durations and placental expulsion times than normal sows (n = 621) (p < 0.001).
- Anemic sows had a lower number of piglets born alive when compared to normal sows (p = 0.03) although total born and stillbirth rates were not statistically different.
- Anemic sows had lower blood glucose (p = 0.02) and cholesterol (p = 0.005) concentrations and higher prepartum progesterone concentrations (p = 0.03). ( The researchers commented that progesterone concentrations and farrowing durations increased with longer intervals between sampling and farrowing and this highlights the importance of timing in hormonal assessments.)
- The study showed that progesterone levels, sampling interval, gestation length, and hemoglobin concentration were significant predictors of farrowing duration and together these factors could explain 58 % of variability in farrowing outcomes.
Take Home Messages:
- Anemia during late gestation was associated with prolonged farrowing, altered metabolic status, and impaired reproductive outcomes in sows.
- These findings with respect to hemoglobin levels in sows at farrowing are in agreement with a study carried out by KA McClellan , S Sheffield , C L Levesque at South Dakota State University. Those researchers reported that maintaining HbC above 10 g/dL appears beneficial for sows, as lower concentrations of HbC are associated with”prolonged labor and increased removal rates”.
- These findings highlight the need for targeted anemia prevention and management strategies to enhance farrowing efficiency and piglet survival in commercial swine operations.
References: P P Thu , R Kirkwood , N Am-In , Effects of gestational anemia on farrowing duration and reproductive outcomes in highly prolific sows in a tropical climate Theriogenology . 2025 Oct 9:250:117701. doi: 10.1016/j.theriogenology.2025.117701. Online ahead of print.
