Investigating Strategies to Optimize Farrowing Performance and Piglet Survival

Sow litter sizes have been increasing over the years. Increasing litter sizes typically result in an increased duration of farrowing which can be detrimental to piglet survival due to the increased risk of in-utero asphyxiation. The cumulative effect of repeated contractions over extended time results in increased pressure on the umbilical cord. This causes an interruption of blood and oxygen to the piglet brain, increasing the risk of death. Although asphyxiation is the cause of the majority of stillbirths, piglets who are born alive can also suffer from in-utero asphyxiation. These piglets are considered to be of low vitality and are severely disadvantaged in regard to survival and growth. Different methods have been explored on ways to decrease farrowing duration, reduce stillbirths, and improve piglet survival, but the neonatal mortality rate is still rather high and is not decreasing. Therefore, new methods need to be investigated in the hopes of successfully decreasing the farrowing duration of sows.

The first project aimed to shorten the farrowing duration and improve piglet survival in farrowing crates via the provision of nesting material and enriched piglet mats. There have been several studies on the effects of nesting material in farrowing crates, but most of those studies use materials that will fall through the slatted floors and block the liquid manure systems. The current study implemented the use of jute as the nesting material and proposed a novel way to present the material, by attaching it to the side of the crate, to prevent it from falling through the slatted floors and disrupting the manure systems. The enriched piglet mats were made from a microfiber material to promote homeothermy and reduce heat loss, thus potentially positively impacting piglet growth and survival. Twenty sows were randomly assigned to 1 of 2 treatments: 1) farrowing crate with jute nesting material (Nest; n = 10; 3 pieces of jute, each 40.6 cm x 21.6 cm) and two enriched piglet mats made from an acrylic board (28.0 x 86.4 cm) covered with a microfiber material, or 2) farrowing crate without nesting material (Control; n = 10) and 1 standard rubber mat (28.0 x 86.4 cm) for piglets. Sows had access to the jute material from approximately d 113 of gestation until they finished farrowing, while piglets had access to the mats for the first 3 d of age. Sow saliva was collected to measure Immunoglobulin A (IgA) and cortisol to assess stress on d -1, 0, 1, and 2, relative to farrowing, and a final sample at weaning (d 16.9 ± 0.18). Piglet plasma Immunoglobulin G (IgG) was collected from 4 piglets/litter at 48 h, 7 d, and weaning. Piglet skin temperature was measured from two piglets/litter using an infrared camera for 3 d after birth. Video was continuously coded for observations of jute-directed and crate-directed interactions. Nest sows performed less crate-directed behavior than Control sows (P = 0.02), while both groups performed the same amount of total nesting behavior (the sum of crate-directed plus jute-directed behavior) (P > 0.05). Cortisol tended to be less in Nest sows (P = 0.08), but there was no difference in IgA concentrations (P > 0.4). Nest piglets tended to be heavier on d 7 (P = 0.095), had greater IgG concentrations (P = 0.03), and greater skin temperatures (P = 0.02). There were no differences in farrowing duration or number of stillbirths (P > 0.7).

The second study investigated the effects of a dietary supplement, 6.6% resistant starch (RS), on sow farrowing performance and piglet survival and vitality. Since RS has been shown to help stabilize blood glucose levels post-prandially, it was hypothesized that RS would decrease farrowing duration by improving the energy status of sows during farrowing. Forty-two sows were balanced for parity and randomly assigned to 1 of 2 treatments: standard lactation diet (n = 21) or diet containing RS (n = 21). Sow blood was analyzed for glucose concentrations at baseline, after 1 wk of being on their respective diets, and during farrowing. Blood glucose for RS sows increased between the beginning and end of farrowing while Control sow blood glucose decreased (P = 0.04). However, there were no other effects on sow blood glucose. Farrowing duration and number of stillbirths did not differ between treatments (P > 0.05). Piglet blood glucose concentrations for RS piglets tended to increase as the birth order increased, while blood glucose for the Control piglets tended to decrease. The other piglet vitality measures, assessed by blood lactate, pH, partial pressure of carbon dioxide (PCO₂), partial pressure of oxygen (PO₂), total carbon dioxide (TCO₂), bicarbonate (HCO₃), base excess (BE_ecf), and oxygen saturation (sO₂) did not differ between treatments (P > 0.05).

In conclusion, farrowing duration was not successfully decreased by the provision of jute nesting material attached to the side of the farrowing crate or by supplementation of RS. However, the jute nesting material and enriched piglet mats did positively impact sow welfare and piglet measures to an extent, although this did not translate into improved piglet survival. The resistant starch supplementation seemed to impact sow glucose during farrowing, but not enough to impact farrowing performance or piglet survival or vitality. These results could be because the nesting treatment was not robust enough to allow sows to fully express their nesting behavior needs in order to impact farrowing performance, while the RS supplementation may have been too low of a dosage, not fed long enough, or a less effective type of RS. Novel ways to optimize sow farrowing performance and piglet survival are still needed.