The effect of digesta sampling time and dietary protein source on ileal nitrogen digestibility for the growing rat

Abstract

The effect of time that digesta were collected on the quantity and representativeness of ileal digesta and on the determination of apparent and true ileal nitrogen (N) digestibility for growing rats was investigated. Semi‐synthetic diets containing chromic oxide as an indigestible marker were given to 200 g live weight rats for 8 days as a single daily meal. The experimental treatments comprised six diets (lactalbumin, soy protein isolate, wheat gluten, fish, protein‐free (PF), enzymically hydrolysed casein (EHC)) and four ileal digesta sampling times (3, 4, 5 and 6 h after the start of feeding). On the eighth day the rats were fed and slaughtered according to treatment, and digesta were sampled from the terminal ileum. Endogenous ileal nitrogen excretion was determined using both the protein‐free and peptide alimentation methods. There was a significant (P = 0.027) effect of experimental diet averaged across sampling times for chromium recovery (CrRec). The CrRec was higher for the rats fed the PF diet than for the other diets. Responses to sampling time varied significantly (P < 0.05) among diets for ileal digesta weight (IDW), nitrogen/chromium (N/Cr) ratio, ileal digesta weight relative to dry matter intake (IDW/DMI), CrRec, N flow, apparent N digestibility and true N digestibility (determined using the protein‐free method). The optimal digesta sampling times for each of the diets were 3 h for PF, EHC, lactalbumin and fish and 4 h for soy protein isolate and wheat gluten. Consequently, 3 or 4 h after the start of feeding is recommended as the optimum ileal digesta sampling time for most purified protein sources when fed to the growing rat as a single daily meal. © 2002 Society of Chemical Industry

Inclusion of wheat gluten as a protein source in diets for weaned pigs

“…This agrees with the results observed by Butts et al [3] when ileal N digestibility of wheat gluten was compared with fish meal, lactalbumin and soy protein isolate. Ammonia-N concentration in digestive contents might be considered as an index of microbial deamination and therefore reduced the amino acid availability for absorption in the small intestine.…”

The effect of food dry matter intake on the flow of amino acids at the terminal ileum for rats fed an enzyme‐hydrolysed casein‐based diet

“…The present study, by virtue of the flexibility in its design, gave the opportunity to determine whether food dry matter intake would affect the endogenous flow of amino acids at the terminal ileum. Earlier work had shown that a meal feeding regimen was suitable for obtaining representative samples and the measurement of endogenous amino acid flows 6. 13 The procedure adopted for this study, which was based on a meal feeding regimen, was successful in obtaining a range of food dry matter intakes.…”

“…On day 15, at the completion of the experimental feeding period, the rats were rendered unconscious by asphyxiation in carbon dioxide gas and then killed by decapitation. Rats were killed 3 h after the food pots were placed in the cages to start the meal feeding period 6. On the final day the times of placing food in the cages were staggered to enable the ileal digesta samples to be collected within 20 min of the predetermined elapsed interval.…”

Available (Ileal Digestible Reactive) Lysine in Selected Pet Foods

“…Twenty experimental diets were formulated to each contain 100 g/kg protein, such that each cat food was the sole source of protein in the respective diet. The respective inclusion rates for the 20 cat foods (diets [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] were 236, 221, 235, 172, 217, 215, 224, 295, 224, 216, 287, 411, 350, 293, 342, 260, 285, 308, 340, and 243 g/kg. Other dietary ingredients were 50 g/kg purified cellulose, 100 g/kg sucrose, 50 g/kg soybean oil, 50 g/kg proprietary vitamin mix, and 50 g/kg proprietary mineral mix.…”