Characteristics of Swedish gilts at service and producers’ opinions about gilt production

Abstract: In Sweden, selection for leanness in pigs has been going on for almost a century. This sometimes results in gilts and sows being too lean and consequently in a risk for reduced reproduction and health status. The Swedish recommendation includes that gilts should be mated after seven months of age, after one documented oestrus, at 120-140kg live weight and with a backfat thickness of 16-20mm. Five gilt producing herds were visited and records of age, heart girth (for weight estimation), body condition (visual estimation), backfat thickness and exterior were made. The same records were also taken in four gilt buying herds on newly purchased gilts. Interviews were made with all farmers regarding the relationship to customers or producers, gilt rearing, gilt characteristics at first service and what a good gilt look like. The statistical analysis showed that gilts are inseminated at an average age of 245 days, at 156kg live weight and with an average backfat thickness of 13.3mm. The exterior status was good among all gilts. The interviews confirmed that gilt producers and the gilt buyers agree on what a good gilt should look like. One difference regarding traits of a good gilt was that the gilt producers sometimes focused more on direct production traits like litter size, while their gilt buyers found traits like body condition, exterior and age more important. Both producers and buyers stressed that age and size are most important when inseminating gilts. As long as the gilts had at least 12mm backfat both parts seemed to be satisfied. Based on the literature, the records and the interviews, a change of the current recommendation on backfat thickness is suggested. The proposed recommendation includes that gilts should be mated between seven and nine months of age, on the second or third oestrus, at around 140kg live weight and with a backfat thickness of 13-18mm. Some producers asked for a production follow-up, and the thesis includes a draft of a follow-up form that gilt producers can send to their customers.