The study defined a set of criteria to assess piglet maturity at birth. This new tool can help farmers evaluate future performance of newborn piglets and assist in reducing their related costs thanks to a more fluid litter management.

In recent years, the race to the hyper-prolific sow has given rise to important litter heterogeneity at birth. Heterogeneity later affects zootechnical performance: mortality, daily weight gain, live weight at weaning. Nevertheless, piglet weight at birth by itself is not discriminating enough to predict the animal’s productive life. Its level of maturity, linked to its intra-uterine development, appears as a more accurate prediction tool to evaluate piglet survival chances and weaning weight.

Audrey Sacy, who conducted the study, explains: "Piglet immaturity is largely underestimated, while it plays a great part in litter heterogeneity. It does affect survival in maternity (in our study, immature piglets survival attained no more than 62 per cent versus 89 per cent for the mature piglets). It also causes growth retardation: average live weight at weaning was 4.7kg for the immature piglets versus 5.7kg for the mature ones. Far from being an isolated phenomenon, immaturity affects all sows at every birth rank. In our study, 11 per cent of the live born piglets were concerned. This can go up to 25 per cent for older sows.”

The study presented in Paris was conducted in 2008 at a 400-sow farm in Brittany. In total, more that 900 piglets were monitored from birth to weaning.

This study provides pig farmers a new tool made of a set of simple criteria aimed at identifying immature piglets at birth:

• Morphological criteria: immature piglets are generally lighter, with a big oval head, a straight, 'dolphin-like' forehead and bulging eyes, no skin folds characteristic of older piglets.
• Behavioural criteria: immature piglets are usually found isolated from the other piglets, lying on their side, and show characteristic behaviour: vocalise, contractions-stretches.

These criteria have been validated by anatomic data: mature and immature piglets show significant differences in the weight raios of their vital organs.

Considering the outcome of immature piglets at farm level as well as the associated costs (mortality, care, delay in building rotation etc.), piglet maturity at birth is indeed an interesting criteria which could be evaluated on a regular basis at farm-level, but which could also be integrated into future sow genetic selection.