Effects Of Casein Hydrolysate And Insulin On The Functional Development In The Liver Of Neonatal Piglets

The aim of this study was to explore the effect of milk-borne bioactive peptides on the functional development in the liver of neonatal pigs. Insulin and casein hydrolysate were fed to experimental animals including normal weight (NW) and intrauterine growth retardation (IUGR) neonatal pigs. Fifty neonatal pigs were selected from thirteen litters (one or two NW and one or two IUGR neonatal pigs from one litter) and divided into newborn group (N), milk group (M), insulin group (I), casein group (C) and casein hydrolysate group (CH). The piglets in group N were killed and sampled immediately after birth. Piglets in groups M and I were fed milk and milk supplemented with 66IU-L-1 insulin, respectively. The piglets in groups C and CH were fed milk substituted 1.5% casein and 1.5% hydrolysed casein solution for 10% (v/v) milk, respectively. The piglets were fed by 30ml/kg body weight every three hours. The piglets were slaughtered and sampled after feeding three days. The enzyme activities and biochemical indices were analyzed according to appropriate methods.The results were demonstrated that the concentrations of protein in liver significantly increased in group CH (216.57 48.38mg-g-1 in NW pigs, 231.66 31.95mg-g-1 in IUGR pigs) and in group C (160.74 38.86mg-g-1 in NW pigs, 184.49 19.54mg-g-1 in IUGR pigs) than that in group N (116.64 10.56mg-g-1 in NW pigs, 109.06 13.91mg-g-1 in IUGR pigs) (P<0.01) after artificially reared three days. Liver protein content was higher in group CH than that of group C (P<0.05) and it also showed a tendency to be higher in IUGR pigs than that in NW pigs (P>0.05). The concentrations of plasma urea nitrogen showed a tendency to decrease in group CH (104.35 35.18mg-L-1 in NW pigs, 230.67 84.45mg-L-1 in IUGR pigs) than that of group C (132.73 41.78mg-L-1 in NW pigs, 306.95 72.26mg-L-1 in IUGR pigs) (P>0.05). It showed the same tendency between NW and IUGR pigs (P>0.05). The activity of GOT in the liver of IUGR pigs in group CH markedly increased than that of group C (P<0.05), and it also showed the same tendency betweengroup CH and group C in NW pigs (P>0.05). After three days, liver glycogen contents in M, I, C and CH group all decreased significantly than that of group N (P<0.01). In contrast, there was a marked increase in the concentration of plasma FFA and insulin and the activities of LDH, GPT and CAT of the liver in M, I, C and CH group than those in group N (P<0.01). The content of plasma glucose and the activities of lipase, HL, G-6-PD, ICD and SOD were showed no significantly difference in M, I, C and CH group when compared with the N group (P>0.05). The concentration of plasma insulin in group I (10.26 2.02mIU-L-1)was higher than that in group M (7.81 1.34mIU-L-1) in NW pigs (P<0.05), and it showed same tendency in IUGR pigs (P>.05).In conclusion, great changes took place in proteometabolism, glycometabolism, lipometabolism and antioxidation function in the liver of piglets during the early postnatal period. The casein hydrolysate significantly stimulated protein synthesis in the liver and upgrowth in IUGR neonatal pigs, however, insulin was no significantly effect on the protein synthesis in the postnatal liver. Casein hydrolysate and insulin showed no significantly effect in glycometabolism, lipometabolism and antioxidation function in the liver of neonatal pigs.