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Abstract Prolonged farrowing duration may have detrimental effects on sows, leading to physical strain and potential complications post farrowing. Severe hypoxia experienced by piglets during farrowing can result in stillbirths or birth of weak piglets, increasing the likelihood of pre-weaning mortality. While the prevalence of anemia in sows has recently gained attention, the consequences of this condition are not yet well understood. Blood concentration of hemoglobin (Hb) has a role in oxygen carrying capacity and thus may influence the resilience of a sow during farrowing. Evaluating Hb in sows before farrowing could offer insights for improving sow welfare and reducing pre-weaning mortality. The primary objective of this study was to examine the relationship between sow Hb and farrowing duration. A total of 57 sows (n = 5, 6, 29, and 17 of parity 1, 2, 3, and 4, respectively) were monitored for Hb using a Hemocue Hb 201+ handheld Hb monitor where sow blood samples were collected before farrowing (on d 112) and between 40 and 48 h after farrowing (i.e., on d 2) from an ear vein using a 20 G needle. Sows were categorized as anemic (Hb 10 g/dL) or non-anemic (Hb ≥ 10 g/dL) based on their Hb at d 112. Among sows that were evaluated, 25 were classified as non-anemic- and 32 were classified as anemic. Surveillance cameras were employed to record the farrowing process for each sow, accompanied by human observation. The time of birth for each piglet was recorded to calculate average birthing interval. Within 12 h of birth, all piglets were weighed individually. Stillborn piglets were identified using a lung flotation test conducted within 1 h of birth. The correlation between sow Hb, farrowing duration, stillborn piglets, and total piglets born was evaluated using the PROC CORR procedure and Proc Mixed in SAS was used to test the effect of Hb category on farrowing duration with total piglets born as a covariate. A negative correlation was observed between pre-farrow Hb and farrowing duration (r = -0.62, P 0.0001). No correlation was observed between farrowing duration and total born (r = 0.22, P = 0.11). However, a significant weak correlation was found between farrowing duration and stillborn piglets (r = 0.32, P = 0.01). Anemic sows had prolonged farrowing duration (7.2 h ± 0.92 min, P = 0.0005) compared with non-anemic sows (3.5 h ± 0.88 min, P = 0.0005). There was no difference in litter size (16.41 ± 0.7 vs 16.3 ± 0.7) for anemic and non-anemic sows, respectively. These findings highlight the importance of sow Hb status at farrowing and indicate sows with decreased Hb may experience prolonged farrowing duration. Strategies to identify anemic sows before farrowing may reduce stillborn rate and improve sow resilience after farrowing.
Sheffield et al. (Wed,) studied this question.