Both the body structure and the body condition, which refers to the extent of the fat layer, change over time in breeding sows. On the one hand, sows have not yet finished growing until their first litter, so they will continue to grow for some time. On the other hand, a certain amount of fat reserves is important for breeding sows because hormone-like substances are formed in the fat cells that influence fertility, and because fat reserves serve as energy stores for the nursing period. Therefore, it is physiologically normal for breeding sows to mobilize fat reserves during the nursing period to ensure a good supply of milk for their piglets, and for these reserves to be replenished afterwards. However, these fluctuations should not be too strong, as sows that are too thin can have impaired fertility and are prone to animal welfare-related problems such as shoulder lesions. Sows that are too fat are more likely to have difficult births.
While extensive data on changes in body condition and recommendations based on this are available for breeding sows in conventional husbandry systems, the data available in the organic sector is sparse. This is due, among other things, to the small market share of organic pig farming and to the fact that measurements on sows in free farrowing systems are time-consuming. Due to the longer suckling period of organic breeding sows, it can be assumed that their body condition develops somewhat differently than that of their conventionally kept counterparts. In the “Sow Condition” project, the body condition of breeding sows is closely monitored over the course of the nursing period under the controlled conditions of the Bio-Institut's experimental facility at the Thalheim/Wels site. The survey of body condition includes weighing the animals, direct measurement of the fat layer using ultrasound, and visual grading. The aim of the project is to be able to display condition progressions under biological husbandry conditions and to show possible connections with aspects of animal welfare and performance.