Impact of mash and crumble diets on intestinal amino acids transporters, intestinal morphology and pancreatic enzyme activity of broilers.

The objective of this study was to evaluate effects of mash and crumble pre-starter diets on pancreatic enzyme activity, intestinal morphology, gene expression of intestinal peptide and amino acid (AA) transporters of broilers. Broilers in battery cages were assigned to different feed forms of pre-starter diet from 1 to 10 days of age. Significantly increased body weight gain (BWG), feed intake (FI) and lowered FCR were observed in birds fed crumble pre-starter diet (CPD, p < 0.05). Feed forms had no effect on whole and small intestine length, but relative intestinal length and relative small intestinal length significantly increased in the broilers fed a mash pre-starter diet (MPD, p < 0.05). Feeding CPD increased the weight of pancreas (p < 0.05), but relative weight of the pancreas was not influenced by treatments. Pancreatic protease and amylase activities significantly increased in the broilers fed CPD (p < 0.05) but the activity of lipase was not influenced. Crypt depth (CD) and villus height (VH) were higher in broilers fed CPD (p < 0.05) but villus width (VW), villus surface area (VSA) and villus height-to-crypt depth ratio (VCR) were not influenced by treatments. mRNA levels for peptide transporter 1 (PepT1), Na+ -independent cationic AA transporter1 (CAT1), Na+ -independent cationic and Na+ -dependent neutral AA transporter 1 (y+ LAT1) and Na+ -dependent neutral AA transporter (B0 AT) were lower in birds fed CPD (p < 0.05). There were no differences in mRNA abundance of Na+ -independent cationic and zwitterionic AA transporter (b0,+ AT) among treatments. Overall, the present data showed that feeding crumble diet during first 10 days of age, through higher FI, enhanced intestinal histomorphology, increased digestive enzyme activity is beneficial to growth performance of broilers. Indeed, dietary form can be an important factor in the expression of jejunal transporters.

Intestinal amino acid and peptide transporters in broiler are modulated by dietary amino acids and protein.

This study evaluated the effect of three levels of digestible amino acids (DAA; 100, 107 and 114% of Cobb recommendations) on mRNA abundance of peptide (PepT1) and amino acid (AA) transporters in 480-day-old broilers during prestarter period. Jejunal mRNA levels of the PepT1 and b0,+AT increased as DAA level increased from 100 to 114%. The expression of CAT1 mRNA in the jejunum was higher in birds fed 100% DAA diet. The transport systems B0AT and y+LAT1 were not affected by the dietary treatments. These results demonstrated that dietary content of protein and DAA differentially affected the expression of intestinal peptide and AA transporters to modulate absorption of peptide and AA in broilers.

Effects of dietary selenium, vitamin E, and their combination on growth, serum metabolites, and antioxidant defense system in skeletal muscle of broilers under heat stress.

This experiment was conducted to evaluate the effects of dietary vitamin E, selenium (Se), and a combination of the two, on the performance, serum metabolites and oxidative stability of skeletal muscle of broilers during heat stress. The broilers raised in either a thermoneutral (23.9°C constant) or heat stress (23.9°C to 37°C cycling) environment were assigned to 6 dietary treatments (0, 0.5, or 1 mg/kg Se; 125 and 250 mg/kg vitamin E; or 0.5 mg/kg Se plus 125 mg/kg vitamin E) from 1 to 49 days of age. At the end of the experiment, blood samples were collected from chicks, the chicks sacrificed, and pectoralis superficialis muscle was used for measurement of malondialdehyde (MDA) concentration and enzyme activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD). The heat-stressed chicks consumed less feed, gained less weight, and had higher feed conversion ratio when compared to thermoneutral chicks (P<0.05). Serum concentrations of iron (Fe) and zinc (Zn) were decreased by heat stress (P<0.05), whereas the serum concentrations of copper (Cu), glucose, and uric acid were significantly increased under heat stress (P<0.05). The chicks that received supplemental of vitamin E exhibited significantly higher serum concentrations of Zn (P<0.05) and significantly lower concentrations of Cu, glucose, and uric acid (P<0.05) when exposed to heat stress. Dietary Se also caused a significant decrease in serum glucose, uric acid, and Cu concentrations of heat-stressed broilers (P<0.05), but had no significant effect on Zn concentration (P>0.05). The GPx activity remained relatively constant (P>0.05), though SOD activity and MDA levels in skeletal muscle were enhanced on exposure to heat stress (P<0.05). The heat-stressed chicks that received the combined supplementary level of vitamin E and Se had the lowest concentration of MDA and the highest activity of SOD in the skeletal muscle (P<0.05). Dietary Se also caused a significant increase in enzyme activity of GPx in the skeletal muscle (P<0.05). These results indicate that the derangement of blood parameters and oxidative stability in broilers under heat stress are improved by supplemental vitamin E and Se.