Selection for longevity works
High total feed efficiency in the value chain is dependent on sows delivering their litters at a steady rate. The cost of producing replacement gilts is substantial and involuntarily culling of a sow will decrease total profit. Reasons for culling are numerous and including each reason as a specific trait in a breeding goal is not feasible. An alternative route is to select for longevity directly, measured by how many litters a sow has produced within a given timeframe.
As Topigs Norsvin we believe in using customer sow management data from all over the world to influence purebred selection at our nucleus farms. Our database contains data from more than 35 million animals and we strive to obtain as much pedigreed data as possible. We currently use two longevity traits; 2nd litter longevity and 5th litter longevity.
The first is a trait that indicates if a sow is bred for a second litter or not. We know that the fall out rate is highest from parity 1 to parity 2 and that if a sow makes it to parity 2 then there is a increased chance she will stay in the herd for multiple parities.
Our goal is to avoid involuntary culling at low parities and so the trait 5th litter longevity is included in the breeding goal. This trait reflects the number of litters a sow has produced within a set number of days after her first farrowing. The genetic correlation between 2nd litter longevity and 5th litter longevity is very high, and a direct selection for 5th litter longevity will lead to an indirect selection for improved 2nd litter longevity.
Longevity has been implemented in the breeding goal of the Topigs lines since 2006 and since February 2016 the trait has been implemented in the Norsvin Landrace