Pre-weaning piglet survival on commercial farms.

Pre-weaning piglet mortality (PWM), a trait highly related to litter size, is one of the main concerns associated with productive efficiency and animal welfare in commercial pig farms. The objectives of this work were to study piglet survival at farm level, to establish a survival rate (SR) as a target indicator to be improved, and to model it based on other reproductive parameters. Analysed data corresponded to 580 Spanish commercial farms with a total inventory of 809,768 sows. These farms showed a mean SR of 85.70% piglets born alive (BA), that decreased to 81.81% when total piglets born (TB) were considered. The SR was strongly associated with prolificacy (P<0.01), the parities with highest prolificacy being those that had the lowest SR. Thus, the highest correlations were for the SR of piglets BA in the 3rd and 4th parities (r=-0.460 and r=-0.452, respectively, P<0.01), and for the SR of piglets TB in 4th parity (r=-0.546, P<0.01), which was the one with the highest prolificacy. The values corresponding to the quartile of farms with the highest SR within the most productive farms were established as targets to be improved, which were ≥88.5% piglets BA and 83.2% piglets TB. Nevertheless, the direct associations shown between the piglet's survival and prolificacy and other productive factors, such as the age of piglets at weaning, the farrowings per sow and year and the farrowing interval, suggest the convenience of modelling the risk of PWM on farms to have its own target of survival index to be improved.