4.3. Assessment of Neonatal Features and Early Postnatal Development of Piglets

At birth, the total number of piglets was recorded for each sow. Sex, weight, and head and body measurements (biparietal diameter, occipito-nasal length, trunk length, and abdominal and thoracic circumferences) were recorded for each piglet. Head measurements were used to calculate the ratio occipito-nasal length/biparietal diameter. Immediately, all living piglets were tagged with earrings for their identification and underwent within-group fostering to equalize the number of animals among dams. Piglets remained with sows in individual pens until weaning at 30 days old.

All the piglets were again weighted and measured at 15 and 30 days old. Weight values were used to determine the ADWG and the FGR; weight gained per day per starting weight) for the time-intervals. At 30 days old, all the piglets were euthanized by stunning and exsanguination in compliance with standard procedures (RD 53/2013) and sampled for determining the effects of maternal metformin treatment on early postnatal body weight and size, adiposity, and body composition. The head was immediately separated from the trunk at the atlanto-occipital joint and weighted, all thoracic and abdominal viscerae were removed, and the weight of the carcass and the total viscerae together were recorded. The back-fat depth and the loin diameter were recorded with a measuring tape at the carcass, and the major organs (heart, lungs, liver, intestine, kidney, spleen, pancreas, and adrenal glands) were weighed individually. The following weight ratios were considered: weights of head to body weight and weights of brain, heart, lungs, liver, kidneys, intestine, pancreas, spleen, and adrenal glands relative to both total body weight and total viscera weight.