Environmental and sow-related factors affecting the duration of farrowing.

A short duration of farrowing is important for piglet survival as a delay can increase the number of stillborn. Many factors may affect the duration of farrowing, including breed, age of the sow, length of gestation, number of piglets born, housing (CRATE vs. PEN), body condition of the sow and state of constipation. The aim of the present study was to investigate these factors and how they interact with each other and thus increasing the risk of prolonged farrowing. The total duration of farrowing and average piglet birth interval were recorded in 172 sows from two herds (HERD-1, n = 76; HERD-2, n = 96). Back-fat measurements and intestinal activity (based on the mean of a constipation index) were measured in all 172 sows. The total duration of farrowing was 272 +/- 152 min (mean +/- SD, n = 172): 301 +/- 165 min (n = 115) in the CRATE group and 212 +/- 95 min (n = 57; P < 0.05) in the PEN group. The average piglet birth interval was 26 +/- 25 min (mean +/- SD, n = 172): 29 +/- 29 min (n = 115) in the CRATE group and 19 +/- 10 min (n = 57; P < 0.05) in the PEN group. Housing (P < 0.05), stillborn (P < 0.001), back-fat average (P < 0.001) and constipation index (P < 0.05) significantly correlated with the duration of farrowing. In conclusion, allowing the sow to move freely before farrowing, reducing the constipation state and avoid excessive fattening during late pregnancy all appear to be key factors in shortening farrowing time and reducing perinatal mortality.