Behavior, physiology, and performance of sows and their litters produced on a sustainable pork farm

Intensive indoor confinement is the predominate system for the lactating sow and her piglets in the United States (US). Even though these operations yield increased pig performance and provide an inexpensive product, they have been criticized with regard to animal well-being. One alternative is a sustainable outdoor system, however sows and their litters in outdoor systems are exposed to varying climatic conditions and with increased sow mobility the well-being of the piglets becomes questionable. This dissertation covers the areas of: (a) behavior and performance of lactating sows and piglets reared indoors and outdoors, (b) farrowing accommodation designs for the outdoor lactating sow, (c) causes and timing of piglet mortality inside the farrowing hut, and (d) behavior, physiology and performance of the outdoor lactating sow during the hot summer months.

In the first study, 287 Newsham sows and their litters were used to determine the effects of intensive indoor (n = 147) and intensive outdoor (n = 140) production systems on sow and litter performance and behavior. Although outdoor sows and their piglets showed a richer behavioral repertoire, the performance between the two systems were similar indicating that production in a well-managed outdoor unit can compete with an intensive indoor system.

In the second study, 206 PIC sows and their litters were used to determine the effects on performance when sows had either a short wooden or tall metal fender and had either insulated or uninsulated farrowing huts. A total of 301 PIC lactating sows and their litters were used to determine the effects on performance when sows had either a roller or board attached to the tall metal fender. Fender design (tall metal versus short wooden) and insulation status (insulated versus uninsulated) were not different in performance. However when short wooden fenders and insulated huts were combined lighter litters were weaned. Fender design did not reduce the time required to process a litter and temperature and relative humidity inside insulated and uninsulated huts were not different. There were no performance differences between rollers and boards attached onto tall metal fenders.

In the third study, 336 PIC sows and their litters were used to determine the effects of sow behavior in the first 72h after parturition to determine piglet mortality. Sows either crushed (CR) piglets or did not (NC). CR sows spent more time inside the hut by day three and prior to killing a piglet spent more time lying on their sternum compared to NC sows. NC sows pawed the straw more than CR sows when inside the huts and CR sows had a larger litter at farrowing and a higher mortality rate, which resulted in similar numbers of piglets being weaned in both treatments.

In the fourth and final study, 110 PIC sows and their litters were used to determine the effects of shaded (SH) or unshaded wallows (CO) on sow behavior, physiology, and performance. Although no differences were found between the wallow treatments (SH versus CO) for any parameter, wallow treatment interacted with air temperature to influence drinking behavior of the sow and some physiological parameters, for example respiration rate, total white blood cells, Neutrophil to Lymphocyte ratio and chemokinesis. No physiological parameters measured were outside normal ranges for an adult sow suggesting that the sows were coping with the increased heat load. The lactating sows spent a large percentage of their time budget inside the farrowing hut and this resulted in unacceptably high preweaning mortality (32%). Therefore there is a need to redesign the farrowing environment to amorahte the increasing heat load on the sow and improve piglet well-being by decreasing preweaning mortality.

This dissertation investigated the effects of swine housing systems on the behavior, physiology, and performance of the sow and her litter. Although sows and piglets engaged in an enhanced behavioral repertoire permitted through the unrestricted housing design, it is still possible to achieve competitive performance levels that are comparable to that of intensive indoor swine systems. Summer months in West Texas become a critical period when lactating sows are kept outside on pasture. Further techniques to reduce summer mortality need to be investigated.