| Piglet early weaning can improve the reproductive efficiency of sow, the conversion of feed, the utilization of delivery equipment and control the vertical transmission of disease. However, early weaning is a stress response for piglets, it could lead to "piglet early weaning stress syndyome". Piglets would encounter various factors after early weaning, such as:weaning stress and the changes of feed. These factors will lead to the atrophy of intestinal villus, the hyperplasia of crypts and other obvious change in the structure and function of the digestive tract. The function of endocrine system will change with the stress response, and the secretion of stress related hormones will increase during stress response, such as catecholamine and cortisol. Catecholamine such as epinephrine and norepinephrine plays an important role in the immune and stress response of host. Even more important, these catecholamine also can affect the proliferation and related virulence factor expression of bacteria and other microbial.In order to reveal the effect of early weaning (EW) at 14 day on the morpholoy of porcine small intestine mucosa and related hormones. Three nests Large-White piglets were chosen in this study, three piglets were chosen to be killed and taken samples from 3 nests at 14 days old. Then the other piglets were randomly divided into EW and CON(control) groups, they were killed at 15,16,18 and 21 days old respectively and the tissue samples were taken. The results of this study are as follows:1.The effect of early weaning on the morpholoy of piglet small intestine mucosa.The small intestines were collected respectively from 27 pigs killed at 14 (pre-weaning),15(1-day-postweaning),16(2-day-postweaning),18(4-day-postweaning),21(7-day posrweaning) day of age. The results show that in the 4 days postweaning, the EW piglets had shorter villi, deeper crypts, and reduced ratios of villus length:crypts depth (VL:CD) compared with CON pigs. At 16 day of age (2 day postweaning) in EW piglets, the villus length in duodenum was 24.72%(P<0.05) shorter, crypts depth in duodenum and jejunum were 19.82%(P<0.01) and 33.79%(P<0.01) greater, and the ratios of villus length:crypts depth (VL:CD) in duodenum reduced 33.79%(P<0.01) respectively in EW pigs than in CON pigs. The villus length in jejunum and ileum were 54.63%(P<0.05), 32.28%(P<0.05) shorter, crypts depth in duodenum, jejunum and ileum were 12.2%(P<0.01),10.18%(P<0.01) and 11.54%(P<0.05) greater, the ratios of VL:CD jejunum and ileum were reduced 59.10%(P<0.05) and 40.26%(P<0.05) respectively in EW pigs than in CON pigs at 18 day of age (4 day postweaning). The results show that the early stage of EW could lead to villus atrophy and crypt hyperplasia, the mucosal injure will recover in the later stage of EW.2. The effect of early weaning on related hormones in EW piglets.The tissue samples were collected at 14 (preweaning),15(1-day postweaning), 16(2-day postweaning),18(4-day postweaning),21 (7-day postweaning) day of age. The results indicate that the concentration of epinephrine (Epi), norepinephrine (Nor), dopam-ine (Dop) and serotinin (5-HT) in serum and small intestine were rising respectively in E W pigs than in CON pigs in the 4 days postweaning. The concentration of Epi in serum, Epi and Nor in ileum were higher (P<0.05) at 18 day of age (4 day postweaning) in EW pigs than in CON pigs. Comparing with CON pigs, the concentration of glucagon, insulin and interleukin 6(IL-6) in EW pigs were declining (P<0.05) at 15 day of age (1 day postweaning), the concentration of cortisol was rising (P<0.05) after 16 day of age (2 day postweaning). These results demontrate differences in postweaning small intestine mucosa, stress hormones and nutrition between EW and CON pigs. The results show that early weaned stress can lead to the secretion of stress related hormones increase, and the changes can be weaken with the weak of stress respones in in the later stage of EW. |
PDF Full Text Request