Concurrent studies of the flow of digesta in the duodenum and of exocrine pancreatic secretion of calves

1. The duodenal flow of digesta and the concurrent pancreatic secretion were compared when six Ayrshire calves, with duodenal re-entrant and pancreatic sac cannulas, were fed on three reconstituted milks. The diets were: reconstituted, ‘mildly’ preheated, spray-dried skim-milk powder (SK); the same skim milk containing 20 g fat/l (SKF); and reconstituted, ‘severely’ preheated skim-milk powder containing 20 g fat/l (HSKF). The calves were fed ad lib. from teats twice daily from 9 to 21 d of age, each diet being offered for 4 d. Collections of duodenal digesta and pancreatic secretions were made for 12 h after the fourth and eighth meals on each diet.2. The calves tended to have the highest liquid intakes when diet SK was given. After adjustment for differences in intake, diet SK resulted in the appearance of more hydrogen, chloride and potassium ions but less undigested protein nitrogen in the duodenal digesta than with either diet SKF or HSKF.3. Compared with diets SK and SKF, the whey fluids from diet HSKF took significantly longer to leave the abomasum, less H+ passed through the duodenum during the first 6 h after feeding and less Cl− during the whole postprandial period. More undigested protein N and fat from diet HSKF passed through the duodenum during the first 6 h after feeding, although this difference was significant only for protein N during the 1st hour after feeding.4. Over the 12 h postprandial period, the duodenal digesta contained almost exactly the same quantities of polyethylene glycol (PEG), N and fat as those in the meal. The total volume of digesta was 2.25 l greater than the quantity of milk ingested. When the hourly duodenal flows of PEG and fluid were expressed as the square root of the hourly quantities recovered, the pattern of abomasal emptying was rectilinear. The flows of N and fat were curvilinear, when expressed on the same basis.5. The concentration of ‘sodium-free’chloride in the duodenal digesta, in excess of that ingested in the milk, was used as an indicator of the quantity of acid secreted by the abomasum. The relative quantity of acid secreted was greatest with diet SK and least with diet HSKF.6. The pancreatic secretion of fluid was highest during the period 5–9 h after feeding but the secretion of enzyme activity was highest during the first 2 h after feeding.7. Considerable variability in the secretion of enzyme activity was observed and the rate of secretion did not appear to be related to any component of the duodenal digesta.8. Diet SKF was associated with a greater volume of pancreatic secretion and more pancreatic protease secretion than either diet SK or HSKF, but most amylase activity was secreted when diet HSKF was given. Evidence is presented which suggests that pancreatic enzyme activity adaptation occurred when diet HSKF was offered in succession to diet SK or SKF. The secretion of trypsin activity did not differ between diets.

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Concurrent studies of the flow of digesta in the duodenum and of exocrine pancreatic secretion of calves

British Journal Of Nutrition ◽

10.1079/bjn19750023 ◽

1975 ◽

Vol 33 (2) ◽

pp. 181-196 ◽

Cited By ~ 42

Author(s):

J. H. Ternouth ◽

J. H. B. Roy ◽

S. Y. Thompson ◽

Joyce Toothill ◽

Catherine M. Gillies ◽

...

Keyword(s):

Enzyme Activity ◽

Pancreatic Enzyme ◽

Milk Powder ◽

Skim Milk ◽

Milk Proteins ◽

Skim Milk Powder ◽

Protein Marker ◽

Total N ◽

Postprandial Period ◽

Pancreatic Fluid

1. The flow of digesta through the duodenum and the concurrent secretion of the pancreas were studied in four Friesian calves given four milk-substitute diets. The diets were: reconstituted, ‘mildly’ pre-heated, spray-dried skim-milk powder with (SKF) or without (SK) margarine fat or with 50% of the skim-milk powder in diet SKF replaced by soya-bean flour (ASKF) or fish-protein concentrate (BSKF), together with dried whey. The diets were given ad lib. twice daily from 13 to 37 d of age, each diet being given for 6 consecutive days. Collections of duodenal digesta and pancreatic secretions, from cannulas, were made for 12 h after feeding the 6th and 12th meals (‘experimental’ meals) for each diet2. The diets fed as ‘experimental’ meals contained polyethylene glycol (PEG) as a fluid (whey) marker and goat's milk containing [3H]lysine as a marker for total protein; β-carotene was added as a lipid marker to the three diets containing margarine fat3. Over the 12 h postprandial period, the patterns of duodenal digesta flow and secretion of pancreatic fluid did not differ markedly between the four diets. The abomasal outflow of both nitrogen and lipid in a 12 h postprandial period was related to their intakes from the ‘penultimate’(5th and 11th) meals for diets SKF and SK but to their intakes at the ‘experimental meals’ for diets ASKF and BSKF. Secretion of pancreatic enzyme activity was highest during the 1st hour after feeding but the main outflow from the abomasum of total N and lipid occurred 5–10 h after feeding4. The time required for all the whey marker (PEG) to pass through the duodenum was similar for diets SKF and SK, but only 53 and 42% respectively of the ingested protein marker passed through the duodenum in the 12 h after feeding. More acid appeared to be secreted by the abomasum when diet SK was given; also less undigested protein passed out of the abomasum after giving this diet. It is concluded that the physical absence of fat globules in the abomasal clot increases the degree of proteolysis5. The secretions of pancreatic fluid and pancreatic enzyme activity were all markedly lower for diet SK than for diet SKF6. With diets containing non-milk proteins (ASKF and BSKF), abomasal proteolysis was less efficient and the ingested protein passed out of the abomasum more rapidly than for diet SKF. There was no difference in the rate of abomasal outflow of the whey fluids between diets SKF, ASKF and BSKF7. In comparison with diet SKF, diets ASKF and BSKF tended to induce less pancreatic enzyme secretion over a 12 h postprandial period, with the exception of lipase8. There appeared to be no direct relationship between the quantities of any of the pancreatic enzymes secreted during a postprandial period and either the concurrent flow of duodenal digesta or the total quantities of dietary constituents passing through the duodenum.

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The effect of heat treatment on the nutritive value of milk for the young calf

British Journal Of Nutrition ◽

10.1079/bjn19690088 ◽

1969 ◽

Vol 23 (4) ◽

pp. 763-782 ◽

Cited By ~ 41

Author(s):

H. Tagari ◽

J. H. B. Roy

Keyword(s):

Heat Treatment ◽

Nutritive Value ◽

Milk Powder ◽

Skim Milk ◽

Sampling Period ◽

Skim Milk Powder ◽

Protein Nitrogen ◽

High Ph ◽

N Concentration

1. Four Ayrshire bull calves between 8 and 34 days of age and fitted with duodenal and ileal re-entrant cannulas were used to study the effect of heat treatment of the milk they received on the pH and nitrogen composition of the pyloric outflow and ileal contents.2. Milk A contained a spray-dried skim-milk powder pre-heated during the drying process at 74° for 30 min and milk B a similar powder pre-heated at 77° for 15 sec. In milk A about 50% of the non-casein protein N had been denatured.3. Milk B resulted in a lower pH than milk A in the pyloric outflow throughout the sampling period of 6.5 h after feeding. It resulted also in an increased volume of outflow during the 1st h after feeding, a reduced output of undigested protein, an increased output of non-protein nitrogen (NPN) and a different pattern of flow of NPN during the first 4 h after feeding.4. These differences between milk A and milk B were associated largely with different clotting characteristics, which were demonstrated in vitro at two levels of addition of rennet with or without the addition of calcium. The buffering capacity of the two milks was similar.5. Variation between calves in their response to these two milks was attributed to the age of the calves and to differences in inherent clotting or proteolytic activity.6. In the ileal outflow, bacterial activity, as measured by dehydrogenase activity, was positively related to N concentration, but the N concentration when milk A was given did not appear to differ from that when milk B was given.7. One calf had diarrhoea when given milk A at a young age. This was associated with an increased pyloric outflow, an increased outflow of undigested protein but little difference in the rate of proteolysis, and a high pH. In the ileal outflow the volume and amount of N was much increased although the N concentration was reduced.8. It is concluded that the detrimental effect of milk A, found in earlier experiments, was largely associated with high pH and poor digestibility of protein in the abomasum, conditions which allow multiplication of coliform organisms in the intestine.

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QUALITY OF PROTEIN IN MILK REPLACERS FOR YOUNG CALVES. III. RENNET COAGULATION AND UNDENATURED WHEY PROTEIN NITROGEN CONTENT OF SKIM MILK POWDERS AND COMMERCIAL MILK REPLACERS

Canadian Journal of Animal Science ◽

10.4141/cjas76-039 ◽

1976 ◽

Vol 56 (2) ◽

pp. 335-338

Author(s):

D. B. EMMONS ◽

E. E. LISTER ◽

D. L. CAMPBELL

Keyword(s):

Whey Protein ◽

Milk Powder ◽

Skim Milk ◽

Skim Milk Powder ◽

Plant Proteins ◽

Protein Nitrogen ◽

Rennet Coagulation ◽

Powder Samples ◽

Milk Replacers

Reconstituted commercial skim milk powder samples which produced a firm (> 30 g) rennet curd had high levels (> 4 mg N/g) of undenatured whey protein nitrogen (WPN) as measured by the modified Harland–Ashworth test. However, similar samples which also had high levels of WPN (> 6 mg N/g) had low curd firmness or failed to coagulate. Of 24 commercial samples of milk replacers, 2 formed a soft curd; the rest did not coagulate. Five had high levels of WPN (> 6 mg N/g); one sample contained 17.8 mg N/g, well above normal levels of skim milk powder. Plant proteins may have caused high WPN values and interfered with the Harland–Ashworth test. It was concluded that WPN is neither an acceptable index of rennet coagulability of milk replacers, nor a reliable index for selecting commercially produced skim milk powders with good rennet coagulability.

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Milk-substitute diet composition and abomasal secretion in the calf

British Journal Of Nutrition ◽

10.1079/bjn19760090 ◽

1976 ◽

Vol 36 (3) ◽

pp. 317-335 ◽

Cited By ~ 26

Author(s):

V. J. Williams ◽

J. H. B. Roy ◽

Catherine M. Gillies

Keyword(s):

Milk Powder ◽

Skim Milk ◽

Live Weight ◽

Dilution Effect ◽

Titratable Acidity ◽

Skim Milk Powder ◽

Protein Sources ◽

Milk Substitute ◽

Protease Secretion ◽

Spray Dried

1. The effect of different protein sources in milk-substitute diets on abomasal acidity and proteolytic activity was studied in Friesian calves, aged 20–58 d (Expt 1). The diets contained ‘mildly’ preheated, spray-dried skim-milk powder (MHM), ‘severely’ preheated, spray-dried skim-milk powder (SHM), fish-protein concentrate (FPC) or solvent-extracted soya-bean flour (SF) as the main protein source.2. Gastric juice was collected from abomasal pouches before feeding and at 15 min intervals for 8 h after the morning feed. Samples of digesta were obtained from the abomasum at 1 h intervals during the same period.3. Digesta pH was lower and titratable acidity higher 0-3 h after giving the diet containing MHM than when any of the other three diets was given.4. Acid secretion from the pouches for the different diets was in the order: FPC > MHM > SHM ≥ SF.5. Protease secretion from the pouches, assayed at pH 2.1, was in the order: MHM > SHM = FPC > SF.6. The effect of dry matter (dm) intake and concentration on abomasal acidity was also studied in calves given diets which contained MHM (Expt 2). This diet was reconstituted at either 100 or 149 g dm/kg liquid diet and fed at either 32.5 or 49.0 g DM/kg live weight 0.75 per d. Samples of abomasal digesta were collected as in Expt 1.7. A high intake of dm at a low dm concentration resulted in low acidity of the digesta in the first 3 h after feeding, which suggested a dilution effect. Comparison of two diets of different dm concentration, which were fed in the same volume of liquid, indicated that the greater the dm intake, the greater was the amount of acid secreted.8. It is concluded that the protein sources varied in their ability to stimulate abomasal acid and protease secretion and it is suggested that this may relate to calf performance.

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Relationship between whey protein nitrogen index of skim milk powder and the heat stability of recombined filled evaporated milk

LWT ◽

10.1016/j.lwt.2021.112754 ◽

2021 ◽

pp. 112754

Author(s):

Jianfeng Wu ◽

Chunxia Su ◽

Lorenz de Neve ◽

Ali Sedaghat Doost ◽

Karin De Grave ◽

...

Keyword(s):

Whey Protein ◽

Milk Powder ◽

Skim Milk ◽

Heat Stability ◽

Skim Milk Powder ◽

Protein Nitrogen

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An Evaluation of Dye Binding and Admi Methods for Determination of Undenatured Whey Protein Nitrogen in Skim Milk Powder

Canadian Institute of Food Science and Technology Journal ◽

10.1016/s0315-5463(81)72756-1 ◽

1981 ◽

Vol 14 (3) ◽

pp. 164

Author(s):

M.A. Amer ◽

D.B. Kupranycz ◽

Lea Gay ◽

D.B. Emmons

Keyword(s):

Whey Protein ◽

Milk Powder ◽

Skim Milk ◽

Skim Milk Powder ◽

Protein Nitrogen ◽

Dye Binding

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Effect of β-lactoglobulin phenotype on whey protein nitrogen index and sulphydryl content of skim milk powder

Dairy Science & Technology ◽

10.1051/lait:1999219 ◽

1999 ◽

Vol 79 (2) ◽

pp. 229-244 ◽

Cited By ~ 4

Author(s):

E. Antoinette O'Sullivan ◽

Philip M. Kelly ◽

Richard J. Fitzgerald ◽

Kevin O'Farrell ◽

Matthew F. Murphy ◽

...

Keyword(s):

Whey Protein ◽

Milk Powder ◽

Skim Milk ◽

Skim Milk Powder ◽

Protein Nitrogen ◽

Β Lactoglobulin

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Studies on the Production of Acid Protease by Submerged Fermentation

International Journal of Food Engineering ◽

10.2202/1556-3758.1338 ◽

2009 ◽

Vol 5 (1) ◽

Cited By ~ 5

Author(s):

Shishir Sinha ◽

Shalini Sinha

Keyword(s):

Enzyme Activity ◽

Proteolytic Activity ◽

Enzyme Production ◽

Milk Powder ◽

Skim Milk ◽

Peanut Meal ◽

Tween 80 ◽

Skim Milk Powder ◽

Acid Protease ◽

Aspergillus Awamori

Proteases are enzymes that hydrolyze peptide bonds and, therefore, lead to the disassembly of proteins. Commercially these are extremely important as more than 60% of the total enzyme market is made up of proteases, out of which 40% are acid proteases. The objective of this study was to compare the available standard strains, Rhizopus oligosporus MTCC-556, Rhizomucor miehei MTCC-546 and Aspergillus awamori MTCC-548, which were examined for the production of acid protease by submerged fermentation. Aspergillus awamori showed maximum proteolytic activity and was selected for further optimization studies. During the course of study the medium was altered. Effect of different carbon sources (lactose, sucrose, and combination of these two in same ratios and glucose) on the proteolytic activity of acid protease produced by A. awamori MTCC 548 was studied and it was found that glucose showed highest proteolytic activity. The effect of various concentrations of glucose was also studied on the acid protease production and its 1% concentration was found to be optimum; it showed proteolytic activity of 0.11 U/ml. Among the different nitrogen sources, such as casein, peptone, skim-milk powder and peanut meal, the peanut meal was found better for enzyme production. Peanut meal, with a concentration of .2% in the medium, increased proteolytic activity up to 0.218 U/ml. The effect of additives, such as Tween-80 and chemicals like CaCl2 and skim-milk powder, was also studied and it was found that 0.05% Tween-80 was effective in enzyme production and a proteolytic activity of 0.225 U/ml was obtained. The enzyme extract was separated in the form of supernatant by using centrifuge and the enzyme activity was analyzed by Ansons method using a spectrophotometer. The enzyme produced was recovered by using a saturated solution of 80% ammonium sulphate and protein content was determined by Lowery method using a spectrophotometer. It was found that the specific enzyme activity was increased from 0.155 U/mg proteins to 0.174 U/mg proteins showing a purification fold by a factor of 1.12 by using 80% saturated ammonium sulphate.

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