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.

Hydrolyzed soy protein isolate sustains high nutritional performance in veal calves.

Milk replacers containing skim milk powder or a mixture of whey and soy protein provided by a hydrolyzed soy protein isolate or a heated soybean flour were fed to 1-mo-old calves for 101 d. The isolate and the flour provided 56 and 72% of dietary proteins, respectively. Digestibility of feed constituents was measured between 9 to 14 d and 65 to 70 d of treatment. Digestive function was evaluated by measurement of ruminal pH, plasma kinetics of triglyceride and glucose concentrations, and xylose absorption. Antibody production was also recorded. Growth and carcass characteristics were satisfactory for the control diet and the diet based on soy isolate, partly because of high apparent digestibility of protein and lack of antibody synthesis in response to soy isolate. In contrast, protein from soybean flour was poorly digested and highly immunogenic. Ruminal pH at 2.5 h after the meal was unaffected by dietary treatments. Postprandial changes in concentrations of triglycerides and glucose in plasma suggested a lack of abomasal clotting with both diets based on soy. Xylose concentration in plasma was only slightly affected by dietary treatment and calf age. Hydrolyzed soy protein is suitable for veal calves and can account for at least half of protein intake.

The role of migrating myoelectric complexes in the regulation of digesta transport in the preruminant calf.

Four calves were equipped with an electromagnetic flow probe inside the transverse duodenum and with electrodes at intervals of 2 cm on either side of the probe. Amounts of 0.5, 2.0, 3.5, and 5.0 kg of whole milk were given according to a latin square design. Recordings of digesta flow and myoelectric activity were made during a 5.6-h period after feeding to quantify the influence of migrating myoelectric complexes on digesta flow through the transverse duodenum of preruminant calf under different levels of milk intake. Immediately after feeding, a phase of irregular spiking activity appeared; its length increasing linearly (p = 0.002) with the amount of milk fed. Increasing milk intake led to linear increases in duration (p = 0.001) and total electrical activity (p = 0.002) of the irregular activity phases, quadratic shortening of the quiescent phases (p = 0.021), and linear decrease (p = 0.006) in the numbers of migrating myoelectric complexes. Intermittent flows of digesta, each of them corresponding to a strong spike burst, appeared during irregular spiking activity phases. Augmentation of the milk ingested did not affect the volume of each gush of digesta but caused a cubic increase in the number of gushes (p = 0.023) and in the total volume of digesta (p = 0.009). These cubic effects implied that with increased intake of milk, the duodenum endeavoured to accelerate the flow of digesta in an attempt to return to an "empty state" in about the same time for all levels of milk consumed. This was achieved mainly through adjustments in the duration and activity of the irregular spiking activity phase.

Studies of method of conserving grass herbage and frequency of feeding in cattle. 2. Eating behaviour, rumen motility and rumen fill.

The influence of the method of conserving grass herbage and the frequency of feeding on eating behaviour, rumen motility and rumen fill was studied in growing steers. Silage and hay were offered to twelve rumen-cannulated Friesian steers (average initial live weight (LW) 128 kg) at a restricted level of intake (20 g dry matter (DM)/kg LW) either once or eight times daily. With once daily feeding, the daily intake of hay was consumed in a single large meal which lasted about 2 h, while silage was eaten in many small meals throughout the day. The proportion of the day spent ruminating was higher (0.39) for steers offered hay once daily than for those offered silage (0.28) or hay eight times per day (0.29). There was little effect of conservation method on frequency of rumen contraction, but contractile intensity (integration of frequency and amplitude) increased during the second half of the 24 h feeding cycle in steers offered hay either once daily or eight times daily, while the same effect was only observed when silage was offered once daily. Total daily contractile activity (the integration of the frequency and duration of myoelectric spike bursts) was significantly (P less than 0.05) higher in steers offered hay, compared with silage, once daily. The mean weight of organic matter in the reticulo-rumen of steers offered hay was significantly higher than for silage both with once (1593 v. 1326 g organic matter (OM)/100 kg LW, P less than 0.01) and eight (1367 v. 1160 g OM/100 kg LW, P less than 0.05) times daily feeding. The proportion of the particulate pool which was present as small (less than 1.2 mm) particles was always greater than 0.60.

Sensitisation of preruminant calves and piglets to antigenic protein in early weaning diets: control of the systemic antibody responses.

The immune response stimulated by dietary protein was studied in preruminant calves and piglets. Calves receiving dietary soya developed high serum titres of soya-specific IgG which did not decline with prolonged feeding. IgG1 and IgG2 subclasses showed a parallel rise although IgG1 predominated. Levels of antibody evoked by a combination of oral and parenteral sensitisation with soya protein were significantly greater than by parenteral sensitisation alone. These results suggest that the calves failed to develop oral tolerance. Passively acquired maternal soya-specific antibody did not influence the response to oral or parenteral sensitisation with soya. By contrast, piglets weaned onto a soya-containing diet became hyporesponsive to injection with soya protein. Thus, calves and piglets appear to differ in their ability to control adverse immune responses to dietary antigens. This could influence the severity of gastrointestinal disorders associated with early weaning diets.

Nutrient sensitivity of gastric emptying of digesta in the preruminant calf.

1. Studies of gastric function were made in preruminant calves fitted with a single abomasal cannula, re-entrant cannulas in the duodenum close to the pylorus and recording electrodes on the pyloric antrum and proximal duodenum. 2. Simultaneous measurements were made of gastric emptying of a saline (9 g sodium chloride/l) meal, myoelectric activity of antral muscle and plasma concentration of somatostatin in jugular blood whilst infusing the duodenum with different solutions. The duodenal infusates were isotonic sodium bicarbonate (300 mosmol/kg), hyperosmolar solutions of NaCl (1000 mosmol/kg), sodium carbonate (500 mosmol/kg), sucrose (1000 mosmol/kg), 41 g emulsified butterfat/kg or 60 mM-hydrochloric acid. 3. Infusing the duodenum with isotonic NaHCO3 stimulated intense myoelectric activity of the antral smooth muscle and rapid emptying of the test meal. In contrast, infusions of 60 mM-HCl reduced antral motility and inhibited gastric emptying of digesta. This inhibitory response to HCl infusion was related to a significant (P less than 0.05) increase of somatostatin in peripheral venous blood. 4. The Na2CO3 infusate, like HCl, inhibited gastric motor activity and digesta emptying, but the concentration of circulating somatostatin was only slightly elevated above pre-infusion levels. 5. Compared with the effects of infusing HCl, infusions of emulsified butterfat or hyperosmolar NaCl and sucrose induced a greater intensity of antral motor activity and faster outflow of gastric effluent, although not to the same extent as with isotonic NaHCO3. However, as with isotonic NaHCO3, these infusates did not evoke the release of somatostatin.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mechanisms implicated in the intestinal allergic reaction to soya proteins in the preruminant calf]. / Mécanismes impliqués dans la réaction allergique intestinale aux protéines de soja chez le veau préruminant.

Studies of intestinal motility in calves given antigenic soya protein or sucrose showed disturbances linked to diarrhoea. Disorders arising from feeding antigenic soya protein were distinct from abnormal motility induced by indigestible carbohydrate. Suppression of the digestive disorders by a drug having anti-allergic properties implied the involvement of an immunological mechanism.

A comparison of the antigenicity of soya-bean-based infant formulas.

1. The antigenicity of four soya-bean-based infant formulas (Prosobee powder, Prosobee liquid concentrate (Mead Johnson, Uxbridge, Middx), Wysoy (Wyeth, Maidenhead, Berks) and Formula S (Cow and Gate, Trowbridge, Wilts] was measured by enzyme-linked immunosorbent assays (ELISAs) specific for glycinin and beta-conglycinin. Results were compared with in vivo assessments of antigenicity using guinea-pigs, rabbits and calves. 2. The levels of antigenic glycinin and beta-conglycinin in Wysoy and Formula S were below the limits of detection of the ELISA. Both these proteins were detected in Prosobee powder and Prosobee liquid concentrate with the highest levels, especially for glycinin, being present in Prosobee powder. 3. Wysoy was sufficiently antigenic to evoke a soya-bean-specific serum antibody response in rabbits injected with this formula emulsified in complete Freunds adjuvant. A significantly greater response was obtained when rabbits were similarly injected with Prosobee powder. 4. The formulas varied in their ability to sensitize guinea-pigs for both anaphylaxis and antibody production when given orally, although the differences were not statistically significant. Prosobee powder appeared to be the most antigenic and Formula S the least, with Prosobee liquid concentrate and Wysoy being intermediate. 5. Similar variations in antigenicity were observed when Prosobee powder, Wysoy and Formula S were fed to soya-bean-sensitive calves. These formulas were all capable of provoking intestinal disturbances (seen as increased ileal flow-rate, decreased small intestinal transit time and decreased nitrogen absorption) but the most severe reactions were seen when Prosobee powder was fed and the least with Formula S. 6. Thus the four soya-bean-based infant formulas showed considerable differences in antigenicity. In vivo studies using guinea-pigs, rabbits and calves were in good agreement and broadly correlated with the immunochemical assessment of antigenicity. However, the in vitro and in vivo results did not correspond exactly and levels of glycinin and beta-conglycinin below the limit of detection by ELISA could evoke an immune response in the different animal species. We believe that these variations in antigenicity of different commercial products prepared from isolated soya-bean protein may be important when interpreting the results from studies of the development of allergy in infants given soya-bean-based formulas.

Effect of soya protein on digestive enzymes, gut hormone and anti-soya antibody plasma levels in the preruminant calf.

The effect of a milk substitute diet containing concentrated soya protein on secretory functions of the abomasum and pancreas and on plasma concentrations of gut hormones and soya antibodies was studied. Sixteen calves aged 12-19 weeks were given a milk substitute in which a major part of the protein source was either soya concentrate (soya diet) or skim milk (control diet). The soya diet was prepared by hot aqueous ethanol extraction of soya bean meal to remove oligosaccharides and inactivate antigenic constituents. Circulatory IgG antibodies against soya proteins were found in all of the calves when they were 16 weeks of age. Their titres increased slightly between 16 and 19 weeks, irrespective of the diet. It seems unlikely that the presence of these antibodies was related specifically to the feeding of the soya concentrate. At slaughter the weight of the gastric mucosa and pancreas and quantities of pancreatic protein together with specific activities of trypsin and chymotrypsin were significantly lower (17, 20, 16, 30 and 36%, respectively) with the soya diet. The quantities of enzymes in the gastric mucosa or the specific activity of pancreatic amylase were not affected, whereas that of lipase increased by 26%. Total enzyme activities as well as units per kg live weight gave significant differences only for trypsin and chymotrypsin which were reduced by 43 and 38%, respectively. With the soya diet, fasting concentrations of gastric inhibitory peptide (GIP) and secretin in plasma samples were significantly lower (49 and 34%, respectively). Values of GIP were also lower (54%) 1 h after feeding. In contrast, postprandial values of cholecystokinin (CCK) were 1.4 times greater. No significant differences were found between the two diets for gastrin, vasoactive intestinal peptide (VIP), bovine pancreatic polypeptide (BPP), somatostatine and motilin. In general these observations could be explained, in part, by the more rapid passage of protein and fat from the abomasum to the duodenum following feeds containing soya concentrate. However, these differences in concentrations of gut hormones did not seem to be related to variations in the weights of gastric mucosa and pancreas or activities of pancreatic enzymes.

Survival of dietary antigens in the digestive tract of calves intolerant to soybean products.

Preruminant calves were given a series of feeds containing heated soybean flour. Digesta collected from the small intestine were analysed by haemagglutination inhibition assay for soluble soybean antigens. The presence of undenatured glycinin and beta-conglycinin in ileal contents was associated with digestive disturbances. In vitro experiments showed that, under optimal conditions of pH for protease activity, beta-conglycinin but not glycinin, was unaffected by pepsin and both antigens were resistant to rennin and trypsin. The solubility of glycinin and beta-conglycinin in saline extracts remained high over pH ranges of 2 to 3 and 6 to 10 but under conditions of intermediate pH, about 4.5, solubility was minimal. It was concluded that preruminant calves suffer from gastrointestinal hypersensitive responses to certain soybean products because major proteases of the digestive tract fail to denature soluble antigenic constituents of the soybean protein.

Effect of feed intake on digesta flow and myoelectric activity in the gastrointestinal tract of the preruminant calf.

The effect of feed intake on abomasal digesta outflow and gastrointestinal motility of preruminant calves given whole milk was studied. Digesta collections were made from calves fitted with re-entrant duodenal cannulas. In other calves myoelectric activity was recorded from electrodes implanted on the abomasum and proximal small intestine, sometimes concurrently with recordings from an electromagnetic flow sensor on the duodenum. After a feed of 2-8 kg milk recurring patterns of intestinal myoelectric activity associated with fasting were temporarily interrupted by a period of continuous irregular spike activity; the duration of the post feeding activity increased with intake of milk. Patterns of abomasal digesta flow were characterized by alternating periods of rapid and slower flow with a frequency that corresponded to cyclic change in myoelectric activity of the small intestine. Hourly rates of abomasal emptying of digesta during a 6-h collection period were significantly greater (P less than 0.05) after giving feeds of 6-8 kg milk compared with measurements of flow rate when 2 kg feeds were given. It is concluded that myoelectric activity of the proximal small intestine exercises control over abomasal emptying of digesta by a mechanism which adjusts the mixing and propulsive functions of gut motility in accordance with the amount of milk consumed.

Effect of duodenal cannulation on abomasal emptying and secretion in the preruminant calf.

1. The effect of re-entrant cannulation of the duodenum on digesta flow from, and secretion into, the abomasum of the preruminant calf was studied. 2. Calves fitted with abomasal cannulas and, at the same time or later, with re-entrant duodenal cannulas were given, by abomasal infusion, test feeds containing glucose and minerals. Net volumes of secretory fluids entering the abomasum and amounts of digesta flowing to the duodenum were estimated from changes in concentrations of water soluble markers (phenol red and polyethylene glycol) in digesta samples collected from an abomasal cannula. 3. Amounts of abomasal contents, net volumes of secretory fluids and digesta flow to the duodenum for calves fitted with only an abomasal cannula did not differ significantly from those obtained for animals with abomasal and re-entrant duodenal cannulas. 4. Collecting digesta from a re-entrant cannula and returning it promptly to the animal did not affect net volumes of secretory fluids. Under these conditions with cannulas open to the atmosphere, rather than being connected together, the amounts of digesta entering the duodenum increased slightly but differences were not significant. 5. Weight gains of calves fitted with abomasal and duodenal cannulas were similar to those of intact animals. 6. It is concluded that in calves receiving liquid feeds duodenal re-entrant cannulation is a suitable preparation for investigating digestive processes of the abomasum.

Gastrointestinal allergy to soyabean protein in preruminant calves. Antibody production and digestive disturbances in calves fed heated soyabean flour.

Preruminant calves were fed heated soyabean flour as a constituent of a milk based diet. Within two weeks IgG and IgE antibodies specific for soyabean proteins appeared in their serum. To measure the rate of flow of digesta through the small intestine, other calves were cannulated in the abomasum and distal ileum. They were given single experimental feeds containing heated soyabean flour as the sole source of protein. The production of similar antibodies in these animals coincided with an increase in the rate of flow of digesta produced from an experimental feed. These results suggest the development of a gastrointestinal allergy to soyabean proteins.

Gastrointestinal allergy to soyabean protein in preruminant calves. Allergenic constituents of soyabean products.

Preruminant calves fed heated soyabean flour produced high titres of serum antibodies with specificity mainly for soyabean glycinin and beta-conglycinin. Various soyabean products that had been processed by different methods were analysed by immunological techniques to determine their content of glycinin and beta-conglycinin in soluble and undenatured form. The presence of such proteins in soyabean flour fed to preruminant calves was associated with the development of digestive disturbances and the production of serum antibodies. It is suggested that the suitability of soyabean products for calf nutrition could be assessed by simple immunological methods to detect these constituents.