Impact of sow energy status during farrowing on farrowing kinetics, frequency of stillborn piglets, and farrowing assistance1

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.

We investigated the effect of two types of housing on the duration of farrowing and the physiology of sows before and after farrowing. We assigned 20 sows (PEN) to farrowing pens (210 cm x 335 cm) enriched with straw bedding and 18 sows (CRATE) were placed in farrowing crates (80 cm x 210 cm) with no bedding material. We sampled the animals during period A (from day -5 before farrowing to day +1 of lactation) and during period B (from days +2 to +5 of lactation). We took daily venous blood samples for progesterone measurements and four salivary samples per day (at 09:00, 11:00, 13:00 and 15:00) for cortisol determination. In addition, intensive blood sampling was performed in 18 catheterised sows (9 PEN and 9 CRATE) to determine the level of oxytocin during farrowing. The treatment had no effect on litter size, piglet mortality at birth and weaning, growth of the piglets between days 1 and 5 of life. We found no significant difference in the cortisol concentration between the two groups during period A (p=0.36). Significant difference was found in period B, where the CRATE group had a higher concentration of cortisol than the PEN group (p=0.03). Progesterone concentration did not differ between the two groups (p=0.80). The duration of farrowing was on average 93 min longer in the CRATE sows (n=15), with a mean of 311+/-35 min (mean+/-S.D.), than in the PEN sows (n=19), with a mean of 218+/-24 min (p=0.03). In addition, the mean interval between each piglet expulsion was longer in the CRATE group (n=11), with a mean of 25+/-4 min, than in the PEN group (n=15) with a mean of 16+/-2 min (p=0.05). During farrowing, the post-expulsion oxytocin pulses average tended to be higher in the PEN group (77.6+/-47.6 ng/ml) than in the CRATE group (38.1+/-24.6 pg/ml) (p=0.08). The concentration of oxytocin strongly affected the duration of farrowing (p<0.001). In conclusion, this study showed that the environment influences the physiology of the sow during farrowing and early lactation.

Modern pig farming is still confronted with high perinatal piglet losses which are mainly contributed to factors associated with the progress of piglet expulsion. Therefore the aim of this study was to identify sow- and piglet factors affecting the duration of the expulsive stage of farrowing and piglet birth intervals in spontaneous farrowing sows originating from five different breeds. In total 211 litters were investigated. Breed affected duration of the expulsive stage significantly: the shortest duration was found in Large White x Meishan F2 crossbred litters and the longest duration in Dutch Landrace litters. No effect of parity on the duration of the expulsive stage was found. An increase in littersize (P<0.01), an increase in number of stillborn piglets per litter (P<0.05) and a decrease of gestation length (P<0.05, independently of littersize) all resulted in an increased duration of the expulsive stage of farrowing. A curvilinear relationship between birth interval and rank (relative position in the birth order) of the piglets was found. Besides that, piglet birth intervals increased with an increasing birth weight (P<0.001). Stillborn (P<0.01) and posteriorly presented (P<0.05) piglets were delivered after significantly longer birth intervals than liveborn and anteriorly presented piglets. The results on sow- and piglet factors affecting duration of the expulsive stage and piglet birth intervals obtained in this study contribute to an increased insight into (patho) physiological aspects of perinatal mortality in pigs.