Classification of stunted piglets as a function of head morphology, and influence of the class on health and zootechnical performance
The selection of hyperprolific sows has led to too many fetuses for the average uterine capacity, which results in altered placental development and delayed development of some fetuses. Piglets with intrauterine growth restriction (IUGR) are at higher risk of postnatal mortality, and have poor postnatal growth. The assessment of head morphology can be used as a method to diagnose these IUGRs (Hansen et al., 2019). This study aimed to evaluate the subjectivity of the classification method and determine the influence of the class on piglet health and growth performances. In this study, novice and expert investigators scored 916 photos (profile) of newborn piglets on a scale from 1 (normal) to 3 (retarded) based on their head shape. We tested the effect of these scores on the health, growth and survival of piglets up to 39 days after birth. While the mean score of novices was higher than that of experts (P < 0.001), the investigator's experience had no influence on predictions of growth (P > 0.05). The score was correlated with piglet growth (P < 0.001), with a difference of 1.75 kg at weaning (25.44 ± 0.05 days of age) between scores 1 and 3. Pigs with score 3 had a 10% lower chance of surviving their first 10 days (P < 0.001). However, IUGR piglets did not undergo more treatment than others (P > 0.05). Furthermore, a novel indicator that divides the birth bodyweight by the score (BwS) can estimate the survivability (P < 0.05) and growth of piglets (P < 0.001).