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R Toullec

Publications and source records attributed to R Toullec.

71 records · Page 4Linked to original sources
PubMed1982

[Distribution of enzyme concentrations in the abomasal mucosa of the preruminant calf. Age changes].

The aim of this trial was to draw an "enzyme map" of the abomasum of the preruminant calf in order to determine the secretory capacities of various areas and to study their age changes. Three pairs of calves were slaughtered at 1.5 days and at 10 and 19 weeks. The abomasum was divided into 12 parts (fig. 1). The chymosin and pepsin extracted from each part were separated and assayed. We found large individual variations in the amount and distribution of the enzymes (fig. 2, table 1) but, in all cases, more than 78 p. 100 were present in the fundus, while the antrum usually contained very little. The cardiac part contained as much as the fundic parts of similar size. The distribution of enzymes in the fundus between the parietal and visceral surfaces or between the proximal, median and distal plicae did not seem to change with age. On the contrary, that part of the enzymes provided by the ventral surface (along the greater curvature) increased with age, while the part provided by the dorsal surface (along the lesser curvature) decreased (fig. 2; table 2). However, the supply of the distal region (parts 3 + 7) of the latter surface varied within much smaller limits, and the pepsin/chymosin ratio remained close to that observed in the whole abomasum. Therefore, the distal region would be the most suitable for making an abomasal pouch which would retain the same representativeness in relation to the whole of the abomasum. It could eventually be extended on the side of the distal plica.

Abomasum↗
PubMed1980

[Influence of age on the secretion of gastric juice and electrolytes in the preruminant calf].

Four preruminant Friesian calves were fitted with an innervated abomasal fundic pouch cut from the lesser curvature. They were fed twice daily a milk substitute containing only spray-dried skim-milk powder as protein source. The daily outflow of gastric juice regularly increased from 400 to 1 800 g/day between 2 and 16 weeks of age and did not change later. The daily outflow/100 kg liveweight increased until 7 to 9 weeks of age and decreased later until 30 weeks (fig. 1). The pH of the secretion always ranged between 1 and 2, except during the days following surgery and when the calves were ill (fig. 2). Expressed in absolute terms, the total outflow of hydrogen, sodium, potassium and chloride ions increased with age; this was mainly due to the increase in the outflow of gastric juice since the ion concentration showed a cyclic pattern with age (fig. 3). When expressed on a liveweight basis, the daily ion output alternatively showed increasing and decreasing periods, mainly in relation to changes in concentration, but no significant trend with age was observed (fig. 4).

Abomasum↗
PubMed1980

[The effect of postruminal supplementation of energy or energy and proteins on feed intake in the ruminant calf].

Forty-eight Friesian bull calves were weaned at 8 weeks of age. They were divided into four groups (T, L, LS1 and LS2) 4 weeks before weaning. All the animals were fed a concentrate diet ad libitum, containing 16 p. 100 of crude protein on a DM basis, and hay. The animals of groups L, LS1 and LS2 also received a limited amount (24 p. 100 of the ingested DM) of a liquid supplement of deproteinized whey fed alone (group L) or mixed with 25 (group LS1) or 50 p. 100 (group LS2) of soybean oil-meal. The voluntary intake of DM/kg live weight0.75 was increased before weaning by giving the three liquid supplements (table 1). That effect lasted until 10 weeks of age in groups LS1 and LS2. On the contrary, the DM intake/kg0.75 decreased from 10 to 14 weeks of age in group L. From 15 to 19 weeks, the DM intake/kg0.75 was the same in group L as in group T, but was lower in groups LS1 and LS2. The plasma glucose level was higher in groups LS1 and LS2 than in group T; it was noticeably higher in group L than in group T (table 1). The plasma urea level was always very low in group L; the urea level of groups LS1 and LS2 was lower at 10 weeks of age than that of group T, but was as high (group LS1) or higher (group LS2) at 16 weeks (table 1). It is concluded that the voluntary intake of young ruminant calves is limited by rumen volume until 3 months of age; the supply of lactose or lactose and protein through the rumen bypass allows an increase in intake. After that period, voluntary intake is rapidly regulated by metabolic mechanisms in relation to the degree of satisfaction of energy and protein requirements; glycemia does not play a role in this regulation. As in monogastric animals, the nitrogen/energy ratio has a determining effect on the control of voluntary intake.

Aging↗
PubMed1977

Influence of age, dietary protein and weaning on calf abomasal enzymic secretion.

Using fistulated calves, the influence of the age, type of dietary protein and weaning on the secretion of chymosin and pepsin by the abomasum were studied. The abomasum secreted both chymosin and pepsin when the animals were fed milk. Chymosin secretion appeared to be independent of the age of the animals whereas a slow increase in pepsin secretion was observed as the calves aged. Several preruminant animals were fed either a skim-milk diet or a milk substitute in which proteins were provided by fish, soya or whey concentrates. Each of these 3 milk substitutes led to a decrease in chymosin secretion without modification of pepsin secretion. Chymosin secretion was partly restored when the claves were again given a skim-milk diet. At weaning, chymosin secretion dropped abruptly, but the pepsin level was not affected. These results indicate that milk (most probably its casein fraction) is responsible for the activation of chymosin secretion.

Abomasum↗
PubMedDate not supplied

Nutritional value of the proteins of soybeans roasted at a small-scale unit level in Africa as assessed using growing rats.

Increasing the roasting time of soybeans from 15 (RSF15) to 25 (RSF25) min led to an important decrease in the antitryptic activity and immunoreactivity of the storage globulins, but it did not seem to greatly affect the concentrations of the indispensable amino acids in the protein. The RSF15 and RSF25 flours were used as the only protein sources in balanced diets for growing rats, and they were compared to a diet based on casein in a pair-feeding experiment. When roasted as usually happens at the workshop level (RSF15), soybean flour induced a significant hypertrophy of the pancreas. Increasing the roasting time by up to 25 min considerably improved the nutritional value of the soybean protein, without apparent consequence on the levels of free amino acid pools in the plasma and muscles. The data also indicated that the tissues of the small and large intestines of the young rat were sensitive to the hyperactivity of the intestinal microflora, and also possibly to the residual activity of some antinutritional factors.

Amino Acids↗
PubMedDate not supplied

Morphology and enzyme activities of the small intestine are modulated by dietary protein source in the preruminant calf.

A study was undertaken to assess the impact of the protein nature and soya antigenicity on the morphology and some enzyme activities of the jejunum in preruminant calves. Twenty Holstein calves fitted with a duodenal cannula were fed a liquid diet based on skimmed milk powder (SMP) for 2 weeks. They were then switched onto diets containing a mixture of SMP and either antigenic heated soybean flour (HSF; n = 12) or hypo-antigenic soya protein concentrate (SPC; n = 8) for 8 weeks, after which they were reverted back to the SMP diet for 2 weeks. The diets contained similar amounts of digestible nitrogen and energy, and were fed at a rate of 55 g DM/kg(0.75)/d. Proximal jejunal biopsies were collected just before (week 0), during (weeks 2 and 8) and after (week 10) feeding of the soya-based diets, and were used for morphology measurements and the determination of total alkaline phosphatase, lactase, amino-peptidases A and N, and dipeptidyl peptidase IV activities. Feed intake and growth were similar between the HSF and SPC groups during the experimental period. The effects of antigenicity and the antigenicity x time interaction were never significant (P > 0.05). Villus height decreased (P < 0.01) between weeks 0 and 2, and increased (P < 0.05) between weeks 8 and 10. Villus width increased between weeks 2 and 8 (P < 0.001). Crypt depth also increased between weeks 0 and 2 (P < 0.001). Specific activities of alkaline phosphatase (P < 0.01) and amino-peptidase N (P < 0.05) decreased between weeks 0 and 2. Conversely, those of alkaline phosphatase (P < 0.0001), lactase (P < 0.01) and dipeptidyl-peptidase IV (P < 0.0001) increased between weeks 8 and 10. Specific activities for lactase and amino-peptidase N decreased (P < 0.01) between weeks 2 and 8. The treatments had little effects on the amino-peptidase A activity. In conclusion, the present work demonstrated that soybean protein markedly depressed the morphology and most enzyme activities of the calf small intestine. On the contrary, the in vitro antigenicity of soybean protein had little influence on these parameters in this study.

Aging↗
PubMedDate not supplied

Small intestinal motility disorders in preruminant calves chronically fed a diet based on antigenic soya: characterization and possible mediators.

Intestinal motility disorders and some mediators implicated in these disorders were studied in preruminant calves that had been chronically fed a diet containing an antigenic heated soyabean flour (HSF) for 3 months. The calves in the present study had previously been shown to present strong immune reactions against soyabean proteins, as assessed through plasma antibody titres, direct skin tests and in vitro lymphoproliferation. Four of these calves sensitive to soya were fitted with an abomasal catheter and wire electrodes on the jejunum. Myoelectric activity was recorded over 7 h following test meals containing skim milk powder (SMP), HSF or a non-antigenic hydrolysed soya protein isolate (HSPI). The pattern of myoelectric complexes migrating to the jejunum was regular with SMP (mean durations of phases I, II and III: 26, 38 and 5.28 min, respectively). With HSF, diarrhoea appeared, and the total duration of phase I decreased from 149 to 68 min (P < 0.01) while that of phase II increased from 239 to 328 min (P < 0.01). The mean duration of phase III decreased from 5.3 to 3.9 min (P < 0.01). These changes, including diarrhoea, were substantially reversed by feeding HSPI. When promethazine, a H-1 histamine receptor antagonist, was administered i.v. prior to feeding HSF the number of phases I tended to decrease and diarrhoea virtually disappeared. In contrast, indomethacin, a cyclooxygenase inhibitor, had limited effects on motility patterns and diarrhoea. These disorders were partially reproduced by i.p. administration of platelet-activating factor (PAF) prior to feeding with SMP. These findings suggest that calves chronically fed antigenic soya suffer from immune-mediated motility disorders which are linked to histamine action via H-1 receptors, and possibly with PAF. The role of arachidonic acid catabolites of the cyclooxygenase pathway is probably minor.

Allergens↗