Effect Of Milk Fed Withleucine And Phenylalanine Supplementation On The Development Of Digestion System And Pancreas In Holstein Male Calves

Efficient and healthy farming is the trend for animal production at present. As an important energy source in the diet for ruminant, starch digested by small intestine gain 42% energy more than digested by rumen microbes. Compared with rumen, starch digested in the small intestine are thought as a high-efficiency energy supplies strategy. Nevertheless, only 35~60% of starch entering the small intestine is degraded. It has been suggested that pancreatic α-amylase secretion insufficiency is the principal factors limit energy efficiency of starch assimilation in the small intestine, which further results in feed waste and potential large intestinal acidosis. It is critical to improve pancreatic exocrine secretion for make use of feed and post-ruminal digestion of nutrients. This study uses the oesophageal groove reflex, which exist in the suckling calves, to invest the effect of leucine and phenylalanine on the development of the digestion system and pancreas in dairy calves. This study is composed three trails, including the feeding and the slaughter experiments.Effect of leucine and phenylalanine on the growth performance and serum metabolite in Holstein male calves.The objective of this experiment was to characterize the effect of leucine and phenylalanine on the growth and energy supply in Holstein male calves. 20 Holstein male calves(Birth weight 38±3kg) were randomly separated into control, L(1.435 g/L Leucine were added in milk), P(0.725 g/L phenylalanine were added in milk), M(1.435 g/L Leucine and 0.725 g/L phenylalanine were added in milk), four groups in total with one week for adaption diets and seven weeks for feeding experiment. Leucine and phenylalanine decreased the body length of calves in week eight significantly(P<0.05). Leucine increased concentrations of serum histamine, leucine, threonine, total essential amino acids and glucose significantly(P<0.05), and heart girth/body length index in week eight(P<0.01), and there is also an increased trend for total amino acids(P=0.089), but no difference in insulin(P>0.05). Phenylalanine decreased the heart girth in week eight, concentrations of serum glutamate and glucose significantly(P<0.05), and increased the serum concentrations of phenylalanine and glycine significantly(P<0.05), but no difference in concentrations of CCK(P>0.05). These results showed that leucine and phenylalanine could affect the growth direction of calves by affecting the serum composition of amino acids and metabolites.Effect of leucine and phenylalanine on the gastrointestinal development and digestion enzymes in the small intestine in Holstein male calves.20 calves from the feeding experiment were slaughtered in week eight. Results showed that leucine reduced Isc of rumen and duodenum significantly(P<0.01), and decreased the rumen and reticulum weight significantly(P<0.05), but increased trypsin activity at the 20% relative site of small intestine significantly(P<0.05). Compared with the control group, the Isc of rumen and duodenum of group L reduced 34.1% and 26.9% separately. Phenylalanine has an interaction with leucine on the Isc(P<0.01). It’s inhibited the function of leucine on Isc. There’s no significantly difference on α-amylaseand lactose between treatments This study demonstrated that leucine could reduce the Isc of rumen and duodenum, promote the development of the gastrointestinal tract, and increase the trypsin activity in the small intestine. Phenylalanine has an interaction with leucine on the Isc and depressed the function of leucine on Isc.Effect of leucine and phenylalanine on pancreas growth, pancreatic enzymes activity and relative expression of α-amylase, trypsin and lipase in Holstein male calves.Pancreases were taken from slaughter experiment, the results showed that leucine has a tendency to increase the concentration of pancreatic protein(mg/kg of BW, P=0.068). Phenylalanine increased the concentration of serum insulin. CCK, pancreatic DNA(mg/g) and the relative expression of trypsin(P<0.05), but decreased the pancreatic protein/DNA rate(P<0.05). There was no difference in pancreatic DNA(mg/pancreas and mg/kg of BW), pancreatic protein(mg/g pancreas, mg/pancreas and mg/kg of BW)activity of α-amylase, trypsin and lipase among groups(P>0.05). Group L got the max pancreatic protein/DNA rate, but no difference with any group. These results stated that the function of leucine on modulating pancreas development is different with phenylalanine. Leucine have a tendency to increase size of pancreatic cell, however, phenylalanine tends to increase the number of pancreatic cell. Yet, there is no difference on pancreatic enzymes’ activity between groups.In the present study, leucine and phenylalanine could affect the growth of Holstein male calves and modulate the growth of pancreatic cells. Leucine could promote calves’ progress and growth in the direction in which will have a good performance. What’s more. Leucine could also promote the development of the gastrointestinal tract. And the function of leucine and phenylalanine on modulating pancreas development is different. Leucine has a tendency to increase size of pancreatic cells, however, phenylalanine tends to increase the number of pancreatic cells.Both of the changesare not affecting the total enzymesofpancreas in calves.