Hematological parameters in sows with normal and prolonged farrowing duration and in neonatal piglets with varying degrees of vitality.

This study aimed to evaluate the effects of parity and prolonged farrowing on sow hematology and to characterize the hematological profiles of newborn piglets classified as normal and weak. The study was conducted on a commercial swine herd in the central region of Thailand and involved 86 Canadian Landrace × Yorkshire crossbred sows and 59 randomly selected live-born neonatal piglets from their litters. The sows had an average parity of 3.7 ± 2.4 (range: 1-9). Based on farrowing duration, the sows were categorized into two groups: normal farrowing (<300 min; n = 51) and prolonged farrowing (≥300 min; n = 35). They were also classified by parity into three groups: parity 1 (n = 30), parities 2-5 (n = 30), and parities 6-9 (n = 26). At the end of parturition, 2.0 mL of blood was collected from each sow's ear vein and immediately analyzed for hematological parameters using a handheld i-STAT portable clinical analyzer (i-STAT Alinity, Abbott Laboratories Co., Ltd., IL, USA). For the piglets, a total of 59 randomly selected live-born neonatal piglets were classified into two groups: normal piglets (mean birth weight 1.46 ± 0.24 kg and able to stand within 1 min of birth; n = 30) and weak piglets (mean birth weight 0.64 ± 0.12 kg; n = 29). Within 1 min of birth, approximately 1.0 mL of blood was collected from the umbilical cord and analyzed for the same hematological parameters measured in the sows. Sows experiencing prolonged farrowing (381.9 ± 97.6 min) exhibited higher base excess (BE) values than those with normal farrowing durations (197.2 ± 60.1 min) (4.2 ± 0.5 vs. 2.3 ± 0.4 mmol/L; P = 0.011). They also tended to have higher blood bicarbonate (HCO3-) concentrations (P = 0.082) and slightly elevated pH levels (P = 0.069). Parity number affected several physiological and metabolic indicators in sows. Primiparous sows showed higher rectal temperatures and postpartum fever rates, as well as elevated HCO3-, BE, total carbon dioxide (TCO2), and glucose levels compared with older parities (P < 0.05). Fever rate was defined as the proportion of sows exhibiting a rectal temperature ≥40.0 °C within 24 h after farrowing or ≥39.3 °C at 24-72 h postpartum. Among piglets, normal newborns showed higher levels of HCO3- (P = 0.011), BE (P = 0.004), TCO2 (P = 0.005), sodium (Na; P = 0.005), hematocrit (Hct; P = 0.003), and hemoglobin (Hb; P = 0.005) compared with weak piglets. Live-born piglets born to sows with prolonged farrowing duration had higher pCO2 concentrations (4.1 ± 0.3 vs. 3.2 ± 0.2 mmol/L; P = 0.047) and tended to have lower sO2 (87.2 ± 3.1 vs. 94.0 ± 2.1%; P = 0.074) than those born to sows with normal farrowing duration. The reduction in sO2 was significant in weak piglets (82.3 ± 4.8 vs. 96.0 ± 3.2%; P = 0.023) but not in normal piglets (P = 0.983). In conclusion, sows undergoing prolonged farrowing demonstrate specific physiological adjustments, particularly in acid-base balance, to cope with the metabolic demands of extended parturition. The findings also reveal marked hematological differences among normal and weak piglets, highlighting the potential value of blood parameter monitoring for early identification of at-risk neonates and timely intervention.