Effects of soya-bean products on digestive processes in the gastrointestinal tract of preruminant calves

Graduate Student Literature Review: The past and future of soy protein in calf nutrition

Our objective with this review is to encourage more research about the use of soy protein in young calf diets by learning from the mistakes of the past and acknowledging the promising results found when modern techniques are applied to treat soybeans. Total or partial substitution of milk proteins with soy proteins can represent a substantial increase in the economic efficiency of calf diets as long as it does not affect calf performance. Unfortunately, the results found in the literature indicate that the inclusion of soy protein in diets of young calves usually diminishes growth and health outcomes. The interaction of the antinutritional factors and antigenic proteins in soybeans with the gastrointestinal tract triggers a physiological response with negative consequences for the digestive tract and immune system of the calf. In this article, we highlight the importance of a correct processing method of soybeans by reviewing some of the published research that has evaluated different soy-based ingredients in diets for young calves. Conventional methods such as heating, ethanol extraction, and protein isolation can produce favorable results provided that the final product contains minimum or null amounts of antigenic and antinutritional factors. More recently, further processing methods such as microbial treatment of soybean meal reduces those antinutritional and antigenic factors, and can also increase the quality of soy protein by reducing the peptide size and by triggering the release of bioactive compounds. Experiments in which soy protein modified by this method was fed have increased in the scientific literature during the last decade due to the favorable results obtained in calves as well as in monogastric animals.

Effects of swimming exercise and soybean supplementation on the immune functions of rats fed a high-fat diet

1. In the present study, the effects of swimming exercise and soybean supplementation on the immune functions of rats fed a high-fat diet were examined. 2. Thirty-four male rats were randomly divided into four groups: (i) HS, a high-fat diet sedentary group (n = 8); (ii) HE, a high-fat diet exercised group (n = 9); (iii) SS, a soybean diet sedentary group (n = 8); and (iv) SE, a soybean diet exercised group (n = 9). The high-fat diet was composed of 35% carbohydrate, 20% protein and 35% fat. For the soybean diet, 3% crude soybean extract was substituted for the protein, carbohydrate and fat according to the energy content of the diet. In the exercise groups, rats swam for 60 min/day, 5 days/week for 4 weeks. 3. The subpopulation of CD4(+) cells and the CD4(+)/CD8(+) ratio did not differ significantly between the high-fat diet and soybean diet groups. However, the subpopulation of CD8(+) cells in the spleens of SS rats was significantly higher than that in the spleens of HS rats (P < 0.05). In addition, splenic interferon-gamma secretion in the SE group, with or without conconavalin A stimulation, was significantly increased compared with the SS group (P < 0.05 and P < 0.01, respectively). 4. These results show that regular endurance exercise training with soybean supplementation ameliorates splenic T cell-mediated immunity.

Gut regulatory peptides in young cattle and sheep

This review summarizes recent advances on blood plasma patterns, receptors, secondary messengers and metabolism of gut regulatory peptides (i.e. gastrin, secretin, somatostatin, cholecystokinin, vasoactive intestinal polypeptide, pancreatic polypeptide, gastric inhibitory polypeptide, motilin), in young ruminants during fetal and perinatal stages, during the preruminant stage and at weaning. It also deals with their role in the digestive tract function and postabsorptive changes. Some pathological situations in young ruminants are considered. Recent molecular aspects of digestive enzyme synthesis are also reported.

Analytical criteria for predicting apparent digestibility of soybean protein in preruminant calves

A series of experiments on the use of soybean as a protein source in milk replacers for veal calves was undertaken to determine the relationships between the physicochemical and antinutritional properties and apparent digestibilities of nine soybean products. Soybean provided between 58 and 71% of dietary CP, and skim milk or whey powder provided the remainder. Soybean products were analyzed for CP, native protein, aggregated protein, carbohydrate-linked protein, peptides, antitryptic activity, and immunoreactivity of lectin, glycinin, alpha-conglycinin, and beta-conglycinin. The apparent digestibility of N calculated for soybean protein varied between 59 and 84%. Simple linear correlations were significant between apparent digestibility of soybean N and concentrations of native protein, antitryptic activity, glycinin, alpha-conglycinin, and beta-conglycinin. However, only variation in antitryptic activity, alpha-conglycinin, and beta-conglycinin contributed significantly to an explanation for the variation in apparent digestibility of soybean N in a multiple linear equation. Under our experimental conditions, beta-conglycinin was the best predictor of digestibility of soybean N. Antitryptic activity became the best predictor when soybean products had no detectable beta-conglycinin.

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.

Growth, digestibility, and enzyme activities in the pancreas and intestines of guinea-pigs fed on raw and heated soya-bean flour

The nutritional effects of giving raw (RSF) or heated (HSF) soya-bean flour to young guinea-pigs were investigated in trials 1 and 2, in which the levels of dietary protein were 120 and 190 g/kg diet respectively. The growth rate of animals fed on RSF was lower than that of those fed on HSF. Growth retardation of guinea-pigs fed on RSF was accompanied by a lower apparent digestibility of the protein (0.49-0.53) compared with HSF (0.67-0.76) and lower food conversion efficiency. In RSF-fed animals, increasing dietary protein affected growth and food conversion efficiency negatively. The pancreas of animals fed on RSF and HSF was similar in weight but secreted less trypsin, chymotrypsin and amylase, in RFS-fed animals. It was concluded that the mechanism by which raw soya-bean negatively affects the growth rate of guinea-pigs by reducing the activity of intestinal enzymes, differs from that suggested for rats and chicks, but is similar to that of pigs and calves.

Thermostable factor(s) in soya producing a net excess of secretion in the ligated gut test in pigs

The ligated gut test (LGT) is the standard method for the examination of Escherichia coli strains for enterotoxin production in pigs. As solid pig feed has been associated with diarrhea, soya products (the main protein source for piglets) were investigated with the same test as E. coli strains. After injection of different soya products into ligated segments of the small intestine fluid accumulation was observed, indicating a net excess of secretion. The factor in soya products responsible for this effect was found to be thermostable, as its effect was unaltered after heating at 120 degrees C during an hour. No indications of a possible allergic phenomenon accounting for the fluid accumulation were found. From the results of this study it is concluded that soyabean products can produce results in the LGT similar to those produced by enterotoxigenic E. coli strains.