Evaluation of the electrolyte status in hyperprolific sows on the farrowing process under different housing...

In order to expand previous knowledge about the farrowing process of hyperprolific sows, the effect of calcium, magnesium and phosphor concentration in the blood and the importance of husbandry were examined. The study was performed in a small educational agriculture institution in Germany comprising 61 sows of a hyperprolific hybrid line (BHZP db.Viktoria). The sows were either kept in farrowing crates (n = 36) or pens (n = 25). Blood samples were taken every 30 min during the farrowing process, using a central venous catheter (Cavafix Certo®, 16G, 32 cm, B. Braun SE, Melsungen, Germany) placed in an ear vein. Samples for ionized calcium concentration (Ca_ion) were analyzed directly using epoc® BGEM test cards (Alere GmbH, Cologne, Germany). Samples for total calcium (Ca_tot), magnesium (Mg) and phosphor concentration (P_i) were deep-frozen (minus 80 °C, Innova® U202, Eppendorf SE, Hamburg, Germany) for photometric analysis at a later date. With an average farrowing duration of 267.6 ± 108.1 min (min. 71, max. 602 min), an average of 17.2 ± 4.2 piglets were born. Eutocic farrowing duration was 193.1 ± 75.2^a minutes. Dystocic farrowing duration was 324.9 ± 94.1^b minutes (a:b p < 0.0001). Farrowing duration did not differ between housing conditions (277.1 ± 117.4 min in crates, 275.0 ± 99.0 min in pens, p > 0.05). Dystocic farrowings were characterized by the occurrence of (at least) one time lapse of more than 60 min without piglet expulsion. In general, 35 of 61 sows suffered from dystocic parturition and received obstetrical intervention. 20 of 36 (55.6%) crate housed sows and 15 of 25 (60%) sows in pens experienced dystocic parturition (p > 0.05). Ca_tot measured at the beginning of the expulsion stage had a prognostic value for the rest of the farrowing process. Above a threshold value of 2.385 mmol/l, eutocic parturition could be expected, while sows with a lower Ca_tot value generally suffered from dystocic farrowings. Also, sows with eutocia had significantly higher Ca_tot values during parturition than sows with dystocia (p = 0.001). The beginning of the lactation period was characterized by a rise in Ca_ion (1.17 ± 0.04 to 1.21 ± 0.06 mmol/l; p < 0.0001). Mg was significantly higher before than during farrowing (p = 0.0003). During parturition, Mg decreased gradually from 0.86 ± 0.1 to 0.84 ± 0.1 mmol/l. Afterwards, Mg values showed an 18.45% increase. Sows without farrowing complications showed significantly higher Mg than those suffering from dystocia (p = 0.024). The same significant trend was observed for P_i (p = 0.002). The deficiencies in Ca_tot/ion, Mg and P_i led to insufficient contractions and thus to farrowing problems. Parturition in the pen showed a general positive effect on the well-being of the sows and a stabilizing influence on the metabolic conditions compared to parturition in the crate. Sows in pens had higher Ca_tot (p = 0.055) and Mg (p = 0.0004). In conclusion, the results provide clear evidence that a large proportion of hyperprolific sows suffer from previously unknown deficiencies electrolyte homeostasis around and during parturition, which is reflected by the large number of dystocic farrowings and the deficiencies in electrolyte concentrations during dystocia.