The impact of hemoglobin concentration on farrowing duration in sows

Concerns have been raised about the prevalence of anemia in sows, yet our understanding of its consequences, particularly its impact on the farrowing process, remains limited. This study investigated the relationship between hemoglobin concentration (HbC) and farrowing duration in sows. A total of 101 sows (n = 16 parity 0, 15 parity 1, 24 parity 2, and 46 parity 3 sows) were monitored for blood HbC (Hemocue Hb 201 device) from the ear vein before farrowing (day 112 of gestation) and between 40 to 48 h after farrowing (day 2). Sows were categorized as anemic (HbC < 10 g/dL), or nonanemic (HbC ≥ 10 g/dL) based on their day 112 HbC (i.e., prefarrowing status). Surveillance cameras recorded the farrowing process for each sow, complemented by human observation. Farrowing duration was defined as the time elapsed between the first piglet born and the last piglet born. All piglets were individually weighed within 18 h of birth, and stillborn piglets were identified using a lung flotation test conducted within 1 h of birth. The correlation between sow HbC, farrowing duration, and stillborn piglets was assessed using the PROC CORR procedure in SAS. Additionally, the effect of HbC category on labor duration was tested using the PROC MIXED procedure, with total piglets born included as a covariate. Anemic sows had a prolonged farrowing (7.2 h ± 0.92 min, P < 0.001) compared to nonanemic sows (3.5 h ± 0.88 min), and negative correlation was observed between prefarrow HbC and farrowing duration (r = -0.62, P < 0.001). There was a weak correlation between farrowing duration and stillborn piglets (r = 0.32, P = 0.01). No correlation was observed between farrowing duration and total born (r = 0.22, P = 0.11). There was no difference in total born (16.41 ± 0.7 vs 16.3 ± 0.7) between anemic (< 10 g/dL) and nonanemic (≥10 g/dL) sows, respectively. Factors such as barn temperature on the day of parturition and feed intake the day prior did not influence the observed differences in labor duration between anemic and nonanemic sows. In conclusion, maintaining HbC above 10 g/dL appears beneficial for sows, as lower concentrations of HbC are associated with prolonged labor and increased removal rates. Blood HbC could serve as a valuable biomarker for identifying at-risk sows, thereby aiding in improving herd management and productivity.