This is largely due to breeding companies intensively selecting for this trait and prioritising it in their breeding programs.

However we appear to have now reached the stage where sows are unable to cope with these excessively big litters, which primarily is the result of two factors:

1. As a greater number of piglets are born alive, there is greater variation in birth weights.
2. When a sow has a large litter there is greater competition for teat space; some sows may not have the milking capacity to rear these large litters.

Piglet viability, survival and growth depends primarily on colostrum and milk intake. A sow’s capacity to produce milk can vary during lactation. Milk production is a complex process; however it is a heritable trait.

Hermitage demonstrated that light weight piglets at weaning are less profitable because they grow slower and require more feed to achieve target slaughter weights. To tackle this issue Hermitage has established a comprehensive R & D program which involves the weighing of all Maternal Line litters at weaning.

This data is incorporated into the Hermitage BreedDirect BLUP system with a respective Breeding Value produced. This project led to Hermitage developing the MLI 2; Litter Weight at Weaning.

The results from this work has demonstrated that there is a significant variation in the weaning weight output of Maternal Line sows. Sows producing heavier litters at weaning are profitable for two reasons:

1. A heavier more viable piglet at weaning is better equipped to deal with the various challenges at weaning. These heavier weaned pigs achieve slaughter weight more efficiently and economically, producing the ‘Full Value’ pig.

2. Sows producing heavier pigs at weaning have an increased feed intake and better feed conversion ratio of feed intake to piglet gain, which creates a more economical and profitable lactating sow. The FCR of sow feed intake to piglet gain is approx. 2.7:1.

Litter weight at weaning is a means of selecting for high milk yield (a heritable trait).

Since January 2014 Hermitage Breeding Units have weighed more than 3000 Landrace and Large White litters at weaning to select Dam Line boars for their AI studs with high breeding value for milking ability. 1kg at weaning gives an economic advantage of €3.09 per finished pig.

Hermitage understand that some farms want to focus on improving litter size as a first priority, while other farms are now interested in the weaning weight of the litter as they are satisfied with the number born alive. Hermitage can facilitate this option for its customers by using the MLI 2 index with a higher emphasis on litter weaning weight.

Recently Hermitage recorded a record litter weight at weaning of 138kgs with a third parity sow weaning 14 piglets at 27 days (an average of 9.8kg/piglet). This demonstrates the potential than can be achieved with this trait.