Growth and small intestine histomorphology of low and normal birth weight piglets during the early suckling period

The present study compared growth performance and small intestinal histomorphological changes between low birth weight (LBW) and normal birth weight (NBW) piglets at day 0 and day 7 postpartum. The LBW and NBW piglets (Large White x Landrace x Duroc) from five multiparous crossbred sows were used. At birth, all piglets were weighed and classified into LBW (0.8-10 kg) or NBW (1.4-1.6 kg) piglets. At days 0 and 7 postpartum, one LBW and one NBW piglets per sow were randomly selected and euthanized for sample collection. The results showed that at day 7, the average daily gain and percentage change of body weight from day 0 of LBW piglets were not different from NBW piglets; however, their body weights were still lower than those of NBW piglets (P < 0.01). The organ weights including small intestine, large intestine, liver, spleen and kidney as normalized per 100 g of body weight showed no difference between LBW and NBW piglets at the same day; but they increased with age (P < 0.05). The histomorphological changes of small intestine revealed that the villus height and crypt depth were not different between groups at the same day; but they increased with age (P < 0.01). In terms of the enterocyte turnover rate as determined by the ratio of villus height to crypt depth, at day 7, the LBW piglets had a higher ratio of villus height to crypt depth with significant effect at the duodenum (P < 0.05). Additionally, the proliferative marker index (Ki-67) was also greater in LBW than NBW piglets at day 7 with significant effect at the ileum (P < 0.05). These results indicated that the LBW piglets grew at the same rate as NBW piglets with undisturbed organ developments as evidenced by the similar average daily gain, percentage change of body weight and normalized organ weights. Furthermore, the difference in enterocyte proliferation and turnover rate of the small intestine indicated a difference in small intestine development and function between LBW and NBW piglets. These data suggest that the LBW piglets were not only different from their NBW littermates in the body weight but also in small intestinal histomorphology. (C) 2013 Elsevier B.V. All rights reserved.