The level of distribution of carbohydrases in the small intestine mucosa of pigs from 3 weeks of age to maturity

Laminaria japonica Polysaccharides Improves the Growth Performance and Faecal Digestive Enzyme Activity of Weaned Piglets

The aim of this experiment was to investigate the effect of Laminaria japonica polysaccharide (LJP) supplementation at levels of 100, 200, or 400 mg/kg on the growth performance, faecal digestive enzyme activity, and serum biochemistry and amino acids of weaned piglets. One hundred and twenty weaned piglets (Barkshire × Licha Black, 21 days old, 6.13 ± 0.16 kg) were randomly divided into four groups with five replicates of six piglets in each group based on body weight. Piglets were fed with different levels (0, 100, 200, and 400 mg/kg) of LJP for a 21-day trial. On day 21, faecal and blood samples were collected from one piglet per pen. The results showed that the supplementation of the 200 and 400 mg/kg LJP significantly increased average daily gain (ADG) and average daily feed intake (ADFI) compared to the control group (p = 0.007; p = 0.002), and dietary LJP linearly increased ADG and ADFI (p = 0.002; p < 0.001). In addition, the supplementation of the 200 and 400 mg/kg LJP significantly increased faecal amylase activity (p < 0.001) compared to the control group, and dietary LJP linearly increased faecal amylase and lipase activities (p = 0.001; p = 0.037). Moreover, dietary LJP at 400 mg/kg increased serum histidine content compared to the other groups (p = 0.002), and dietary LJP linearly increased the contents of serum histidine and asparagine in piglets (p < 0.001; p = 0.046). In conclusion, supplementation of 200 and 400 mg/kg LJP could enhance growth performance and faecal digestive enzyme activity and modulate the serum amino acid content of weaned piglets, potentially contributing to the health of weaned piglets.

Impacts of weaning age on dietary needs of whey permeate for pigs at 7 to 11 kg body weight

Background

Whey permeate is an effective lactose source for nursery pigs and the most benefits are obtained when pigs are at 7 to 11 kg BW. Altering weaning ages could cause different length of early-weaner phases until 7 kg BW and thus it would influence the dietary need of whey permeate during 7 to 11 kg BW of pigs. This study aimed to evaluate if weaning ages would affect the dietary needs of whey permeate for optimum growth performance of pigs at 7 to 11 kg BW.

Methods

A total of 1,632 pigs were weaned at d 21 (d 21.2 ± 1.3) or d 25 (d 24.6 ± 1.1) after birth. All pigs had a common early-weaner feeds until they reached 7 kg BW. When pigs reached 7 kg BW within a weaning age group, they were allotted in a randomized complete block design (2 × 4 factorial). Two factors were weaning age groups (21 and 25 d of age) and varying whey permeate levels (7.50%, 11.25%, 15.00%, and 18.75%). Data were analyzed using the GLM and NLIN procedures of SAS for slope-ratio and broken-line analyses to determine the growth response to whey permeate and optimal daily whey permeate intake for the growth of the pigs weaned at different ages.

Results

Pigs weaned at 21 d of age had a common diet for 11 d to reach 7 kg BW whereas pigs weaned at 25 d of age needed 2 d. The G:F of pigs weaned at 25 d of age responded to increased daily whey permeate intake greater (P < 0.05) than pigs weaned at 21 d of age. Breakpoints were obtained (P < 0.05) at 88 and 60 g/d daily whey permeate intake or 17.0% and 14.4% of whey permeate for G:F of pigs weaned at 21 and 25 d of age, respectively.

Conclusion

Pigs weaned at an older age with a short early-weaner phase had a greater growth response to whey permeate intake compared with pigs weaned at a younger age with a long early-weaner phase. Altering weaning ages affected dietary needs of whey permeate for optimum growth performance of pigs from 7 to 11 kg BW.

Birth Weight and Nutrient Restriction Affect Jejunal Enzyme Activity and Gene Markers for Nutrient Transport and Intestinal Function in Piglets

Simple Summary

Birth weight and nutrient utilization are thought to have significant effects on intestinal development in neonatal pigs. The present study evaluated the impact of low and normal birth weight with and without nutrient restriction during the neonatal period on jejunal development. The results observed suggest that during the first 28 d of life, birth weight had greater effects on intestinal development than nutrient level, however, at d 56, the nutrient level was a significant contributor to intestinal function and enzyme activity compared to birth weight. Taken together, both birth weight and nutrient restriction have effects on intestinal development, but may have a greater impact in early life (d 28).

Abstract

Significant variation in the birth weight of piglets has arisen due to increased sow prolificacy. Intestinal development and function may be affected by birth weight. Low birth weight (LBW) pigs may also have reduced feed intake, leading to further impairment of intestinal development. The objective of this study was to examine the intestinal development pattern of LBW and normal birth weight (NBW) piglets with normal nutrition (NN) or restricted nutrition (RN) in the pre-weaning period. Jejunal intestinal samples were analyzed for target gene expression and enzyme activity at d 28 (weaning) and d 56 (post-weaning). At d 28, excitatory amino acid transporter (EAAC1) and sodium-dependent neutral amino acid transporter (B⁰AT1) were downregulated in LBW compared to NBW pigs (p < 0.05). On d 56, B⁰AT1 and ASCT2 (glutamine transporter) were downregulated in RN compared to NN pigs (p < 0.05), regardless of birth weight. Peptide transporter 1 (PepT1) expression was downregulated in LBW compared to NBW pigs at 28 d (p < 0.05), with no effects of treatments at 56 d. Sodium-glucose transporter-1 (SGLT1) was upregulated in NBW-NN compared to LBW-NN pigs (p < 0.05) at 28 d. Alkaline phosphatase (ALP) was upregulated in LBW-RN at d 28. At d 56, claudin-3 (CLDN-3) and Zonular occludin-1 (ZO-1) were upregulated in NN compared to RN pigs (p < 0.05). There were no treatment effects on ALP, maltase, or sucrase activity at 28 d. However, at 56 d, ALP was upregulated in NBW-NN pigs while sucrase activity was upregulated in NN pigs (p < 0.05). The results demonstrate differences in jejunal gene expression associated with birth weight, with reduced gene expression of amino acid transporters (PepT1, EAAC1, B⁰AT1) in LBW compared to NBW pigs (p < 0.05). While neonatal nutrient restriction had minimal effects at 28 d and d 56 for tight junction protein transcript abundance, neutral amino acid transporter abundance was upregulated in NN pigs compared to RN piglets (p < 0.05).

The role of lactose in weanling pig nutrition: a literature and meta-analysis review

Lactose plays a crucial role in the growth performance of pigs at weaning because it is a palatable and easily digestible energy source that eases the transition from milk to solid feed. However, the digestibility of lactose declines after weaning due to a reduction in endogenous lactase activity in piglets. As a result, some lactose may be fermented in the gastrointestinal tract of pigs. Fermentation of lactose by intestinal microbiota yields lactic acid and volatile fatty acids, which may positively regulate the intestinal environment and microbiome, resulting in improved gastrointestinal health of weanling pigs. We hypothesize that the prebiotic effect of lactose may play a larger role in weanling pig nutrition as the global feed industry strives to reduce antibiotic usage and pharmacological levels of zinc oxide and supra-nutritional levels of copper. Evidence presented in this review indicates that high dietary lactose improves growth performance of piglets, as well as the growth of beneficial bacteria, particularly Lactobacillus, with the positive effects being more pronounced in the first 2 weeks after weaning. However, the risk of post-weaning diarrhea may increase as pigs get older due to reduced lactase activity, high dietary lactose concentrations, and larger feed intakes, all of which may lead to excessive lactose fermentation in the intestine of the pig. Therefore, dietary lactose levels exert different effects on growth performance and gastrointestinal physiological functions in different feeding phases of weanling pigs. However, no formal recommendation of lactose for weanling pigs has been reported. A meta-analysis approach was used to determine that diets fed to swine should include 20%, 15%, and 0 lactose from d 0–7, d 7–14, and d 14–35 post-weaning, respectively. However, sustainable swine production demands that economics must also be taken into account as lactose and lactose containing ingredients are expensive. Therefore, alternatives to lactose, so called “lactose equivalents” have also been studied in an effort to decrease feed cost while maintaining piglet performance with lower dietary lactose inclusions. In summary, the present review investigated dose-response effects of dietary lactose supplementation to exert positive responses and begin to elucidate its mechanisms of action in post-weaning pig diets. The results may help to replace some or all lactose in the diet of weanling pigs, while improving production economics given the high cost of lactose and availability in some swine production markets.

Effects and interaction of dietary electrolyte balance and citric acid on growth performance, intestinal histomorphology, digestive enzyme activity and nutrient transporters expression of weaned piglets

Fifty-six piglets were weaned at 21 days and randomly assigned to 1 of 8 dietary treatments with 7 replicate pens for a 14-day experimental period. The eight experimental diets were prepared via a 2 × 4 factorial arrangement with citric acid (CA; 0 and 0.3%) and dietary electrolyte balance (dEB, Na +K - Cl mEq/kg of the diet; -50, 100, 250, and 400 mEq/kg). Varying dEB values were obtained by altering calcium chloride and sodium bicarbonate contents. Dietary CA significantly increased (p < .05) villus height (VH) and villus height:crypt depth (VH:CD) in the jejunum. Piglets fed a 250 mEq/kg diet increased (p < .05) VH and VH:CD values in the duodenum. Jejunal VH and VH:CD increased (quadratic; p < .05), and ileal VH:CD (liner and quadratic; p < .05) decreased as dEB was increased in diets without CA, but no such effect was observed on the diets containing CA (dEB ×CA; p < .05). The CD in jejunum (quadratic; p < .05) increased as dEB was increased in diets containing CA, whereas it was decreased (linear; p < .05) in the diets without CA (dEB ×CA; p < .001). Dietary CA increased maltase activity and reduced the number of Ki67-positive cells (p < .05). Increasing dEB values in diets without CA increased sucrose and lactase activities (quadratic; p < .05), but no such effect was observed in the diets with CA (dEB ×CA; p < .05). An interaction effect between dEB and CA on the number of Ki67-positive cells was observed (p < .001). In conclusion, 250 mEq/kg dEB diet with CA improved piglet intestinal digestion and absorption function by improving intestinal morphology and increasing digestive enzyme activities. However, these improvements were also observed in piglets fed the 100 mEq/kg dEB diet without CA.

The role of liver metabolism in compensatory-growth piglets induced by protein restriction and subsequent protein realimentation

The aim of this work was to study the role of hepatic metabolism of compensatory growth in piglets induced by protein restriction and subsequent protein realimentation. Thirty-six weaned piglets were randomly distributed in a control group and a treatment group. The control group piglets were fed with a normal protein level diet (18.83% CP) for the entire experimental period (day 1-28). The treatment group piglets were fed with a protein-restriction diet (13.05% CP) for day 1 to day 14, and the diet was restored to normal protein level diet for day 15 to day 28. RNA-seq is used to analyze samples of liver metabolism on day 14 and day 28, respectively. Hepatic RNA-sequencing analysis revealed that some KEGG signaling pathways involved in glycolipid metabolism (eg, "AMPK signaling pathway," "insulin signaling pathway," and "glycolysis or gluconeogenesis") were significantly enriched on day 14 and day 28. On day 14, protein restriction promoted hepatic lipogenesis by increasing the genes expression level of ACACA, FASN, GAPM, and SREBP1C, decreasing protein phosphorylation levels of AMPKɑ and ACC in AMPK signaling pathway. In contrast, on day 28, protein realimentation promoted hepatic gluconeogenesis by increasing the concentration of G6Pase and PEPCK, decreasing protein phosphorylation levels of IRS1, Akt, and FoXO1 in insulin signaling pathway. In addition, protein realimentation activated the GH-IGF1 axis between the liver and skeletal muscle. Overall, these findings revealed the importance of liver metabolism in achieving compensatory growth.

Weaning affects the glycosidase activity towards phenolic glycosides in the gut of piglets

Phenolic compounds in pig diets, originating either from feed ingredients or additives, may occur as glycosides, that is conjugated to sugar moieties. Upon ingestion, their bioavailability and functionality depend on hydrolysis of the glycosidic bond by endogenous or microbial glycosidases. Hence, it is essential to map the glycosidase activities towards phenolic glycosides present along gut. Therefore, the activity of three key glycosidases, that is α-glucosidase (αGLU), β-glucosidase (βGLU) and β-galactosidase (βGAL), was quantified in small intestinal mucosa and digesta of piglets at different gastrointestinal sites (stomach, three parts of small intestine, caecum and colon) and at different ages around weaning (10 days before and 0, 2, 5, 14 and 28 days after weaning). Activity assays were performed with p-nitrophenyl glycosides at neutral pH. The αGLU activities in mucosa and digesta were low (overall means 1.4 and 60 U respectively) as compared to βGLU (15.2 and 199 U) and βGAL (23.4 and 298 U; p < .001). Moreover, αGLU activity in mucosa was unaffected by age. Conversely, βGLU and βGAL activities dropped significantly after weaning. Minimal levels, ranging between 18% and 54% of the pre-weaning values, were reached at 5 days post-weaning. Similarly, in small intestinal digesta, reductions from 60% up to 90% were observed for the three enzyme activities on day five post-weaning as compared to pre-weaning levels. In caecal contents, activities were lowest at 14 days post-weaning, while in stomach and colon no clear weaning-induced effects were observed. Our data suggest that weaning affects the glycosidase activity in mucosa (mainly endogenous origin) and digesta (primarily bacterial origin) with the most pronounced effects occurring 5 days post-weaning. Moreover, differences in activities exist between different glycosidases and between gut locations. These insights can facilitate the prediction of the fate of existing and newly synthetized glycosides after oral ingestion in piglets.

Feed intake patterns nor growth rates of pigs are affected by dietary resistant starch, despite marked differences in digestion

Current feed evaluation systems often assume that fermented starch (i.e. resistant starch (RS)) yields less energy than digested starch. However, growth rates of pigs fed low and high RS diets are often the same when feed is available ad libitum. This may be explained by its effect on digestive processes changing feeding behavior, and consequently energy utilization. This study aims to investigate the effect of RS on nutrient digestion and digesta passage rate in pigs, in combination with its effect on feeding behavior and growth performance under ad libitum conditions. In experiment 1, 20 male pigs (40 ± 2.82 kg) were fed diets containing either 50% waxy maize starch (low in RS (LRS)) or high-amylose maize starch (high in RS (HRS)), and soluble and insoluble indigestible markers. After 14 days of adaptation to the diets, pigs were fed hourly to reach steady state (6 h), dissected, and digesta were collected from eight segments. From the collected samples, nutrient digestion and passage rate of the solid and liquid digesta fraction were determined. In experiment 2, 288 pigs (80 ± 0.48 kg; sex ratio per pen 1 : 1; boar : gilt) were housed in groups of 6. Pigs were ad libitum-fed one of the experimental diets, and slaughtered at approximately 115 kg. Feed intake, growth and carcass parameters were measured. Ileal starch digestibility was greater for LRS-fed than for HRS-fed pigs (98.0% v. 74.0%; P < 0.001), where the additional undigested starch in HRS-fed pigs was fermented in the large intestine. No effects of RS on digesta passage rate of the solid or liquid digesta fraction and on feeding behavior were observed. Growth rate and feed intake did not differ between diets, whereas feed efficiency of HRS-fed pigs was 1%-unit higher than that of LRS-fed pigs (P = 0.041). The efficiency of feed used for carcass gain did not differ between diets indicating that the difference in feed efficiency was determined by the non-carcass fraction. Despite a 30% greater RS intake (of total starch) with HRS than with LRS, carcass gain and feed efficiency used for carcass gain were unaffected. RS did not affect digesta passage rate nor feeding behavior suggesting that the difference in energy intake between fermented and digested starch is compensated for post-absorptively. Our results indicate that the net energy value of fermented starch currently used in pig feed evaluation systems is underestimated and should be reconsidered.

Pigs Ferment Enzymatically Digestible Starch when it Is Substituted for Resistant Starch

BACKGROUND

Feeding behavior is controlled by satiety mechanisms, which are affected by the extent of starch digestion, and thus resistant starch (RS) intake. Alterations in feeding behavior to changes in RS intake may depend on the adaptation of processes involved when shifting from starch digestion to fermentation or vice versa.

OBJECTIVES

The aim of this study was to investigate how growing pigs adapt their feeding behavior in response to increasing and decreasing dietary RS concentrations.

METHODS

Thirty-six groups of 6 pigs (25.4 ± 2.8 kg; Hypor Libra × Hypor Maxter; male:female, 1:1) were fed diets containing 50% high-amylose maize starch (high RS; HRS) or waxy maize starch (low RS; LRS). Over 28 d, diets were exchanged following a 5-step titration (25% per step) that was executed in the upward (LH) or downward direction (HL). Twelve groups received a control diet to correct for changes over time. Individual feeding behavior and total tract starch digestion and fermentation were evaluated. The response in each parameter to increasing dietary HRS inclusion was estimated through the use of linear regression procedures, and tested for titration direction and sex effects.

RESULTS

Complete substitution of LRS with HRS increased the proportion of starch fermented, which was greater in LH pigs than in HL pigs (17.6% compared with 8.18%; P < 0.001), and decreased the feed intake (106 g/d; P = 0.021) and meal size (12.6 g; P < 0.001) of LH pigs, but not of HL pigs. In LH pigs, the size of the starch fermentation response positively correlated with the size of the feed intake response (r = 0.90, P < 0.001).

CONCLUSIONS

The attenuated response in starch fermentation in HL pigs indicates that pigs adapt more slowly to dietary supply of digestible starch than to RS, consequently resulting in fermentation of enzymatically digestible starch. Feed intake and feeding behavior only changed in pigs poorly adapting to RS, indicating that adequacy of adaptation, rather than RS itself, drives feed intake. These findings stress the importance of diet history for nutrient digestion and feeding behavior.

Zinc strengthens the jejunal barrier by reversibly tightening the paracellular route

During the postweaning period, piglets are prone to gastrointestinal infections. The resulting impairment of intestinal barrier function may cause diarrhea associated with growth retardation or even death of piglets. Orally applied Zn is commonly used to prevent and treat diarrhea, but its mode of action still needs to be elucidated. To analyze the molecular mechanism whereby Zn acts on porcine intestinal barrier function, ex vivo studies on piglet jejunum and accompanying in vitro studies on a porcine jejunal epithelial cell line, IPEC-J2/PS, were performed with electrophysiological tools. Feeding pharmacological Zn doses exerted no significant electrophysiologically ascertainable short- and long-term effects on jejunal barrier function ex vivo. However, in IPEC-J2/PS, basolateral Zn was cytotoxic since its application caused a release of lactate dehydrogenase and an irreversible breakdown of the epithelial barrier. In contrast, apical Zn application caused an immediate increase in paracellular resistance and a decrease in permeability to the paracellular marker fluorescein, reflecting overall barrier strengthening in vitro. Apical effects were fully reversible upon washout. This indicates that Zn supplemented to feed was completely washed out during ex vivo jejunum preparation. We conclude that there is no evidence for long-term barrier effects through prophylactic Zn supplementation and that extracellular Zn acts acutely and reversibly from the apical side via tightening the paracellular route, thus counteracting leak-flux diarrhea.NEW & NOTEWORTHY Therapeutically administered Zn successfully treats diarrhea in veterinary and human medicine. Here we present data that Zn strengthens the porcine jejunal epithelial barrier by reversibly tightening the paracellular route for inorganic ions and small solutes. Acute or long-lasting Zn effects on transcellular transport (Cl^- secretion) were not detected. We therefore conclude that Zn is useful for acutely treating leak-flux diarrhea rather than secretory diarrhea. Suitability as prophylactic feed supplement, however, is questionable.

Fermentation in the small intestine contributes substantially to intestinal starch disappearance in calves

BACKGROUND

The proportion of starch disappearing from the small intestinal lumen is generally lower in ruminants than in monogastric animals, and there are indications that the starch digestion capacity in ruminants is limited.

OBJECTIVES

Milk-fed calves were used to study the rate-limiting enzyme in starch hydrolysis and to quantify starch fermentation in ruminants.

METHODS

Forty male Holstein-Friesian calves were fed milk replacer containing either lactose (control) or 1 of 4 corn starch products. The following starch products differed in the enzyme ratios required for their complete hydrolysis to glucose: gelatinized starch [α-amylase and (iso)maltase], maltodextrin [(iso)maltase and α-amylase], maltodextrin with α-1,6-branching (isomaltase, maltase, and α-amylase), and maltose (maltase). In the adaptation period, calves were stepwise exposed to an increasing dose of the starch product for 14 wk to allow maximal adaptation of all enzyme systems involved. In the experimental period, apparent total tract and ileal starch product disappearance, total tract starch product fermentation, and α-amylase, maltase, and isomaltase activities were determined at 18% inclusion of the starch product.

RESULTS

Maltase and isomaltase activities in the brush border did not increase for any of the starch product treatments. Luminal α-amylase activity was lower in the proximal (3.9 ± 3.2 and 2.7 ± 1.7 U/mg Co for control and starch product calves, respectively) but greater in the distal small intestine of starch-fed calves than in control calves (0.0 ± 0.0 and 6.4 ± 1.5 U/mg Co for control and starch product calves, respectively; means ± SEs for control and means ± pooled SEMs for starch product treatments). Apparent ileal (61.6% ± 6.3%) and total tract (99.1% ± 0.4%) starch product disappearance did not differ between starch product treatments, suggesting that maltase activity limits starch digestion in ruminants. Total tract starch product fermentation averaged 414 ± 43 g/d, corresponding to 89% of intake, of which half was fermented before the terminal ileum, regardless of starch product treatment.

CONCLUSION

Fermentation, rather than enzymatic digestion, is the main reason for small intestinal starch disappearance in milk-fed calves.

In vitro gastrointestinal digestion study of two wheat cultivars and evaluation of xylanase supplementation

BACKGROUND

The filamentous fungus Talaromyces versatilis is known to improve the metabolizable energy of wheat-based poultry diets thanks to its ability to produce a pool of CAZymes and particularly endo-β(1,4)-xylanases. In order to appreciate their in vivo mode of action, the supplementation effect of two of its xylanases, XynD and XynB from families GH10 and GH11 respectively, have been evaluated on two different wheat cultivars Caphorn and Isengrain, which were chosen amongst 6 varieties for their difference in non starch polysaccharides content and arabinoxylan composition.

RESULTS

Polysaccharides digestion was followed during 6 h along the digestive tract using the TNO gastrointestinal model-1, to mimic monogastric metabolism. Polysaccharide degradation appeared to occur mainly at the jejunal level and was higher with Isengrain than with Caphorn. For both cultivars, XynD and XynB supplementation increased notably the amount of reducing end sugars into the jejuno-ileal dialysates, which has been confirmed by a valuable increase of the soluble glucose into the jejunal dialysates.

CONCLUSIONS

The amounts of arabinose and xylose into the dialysates and ileal deliveries increased consequently mainly for Caphorn, suggesting that XynD and XynB supplementation in wheat-based diet could alleviate the anti-nutritional effects of arabinoxylans by limiting the physical entrapment of starch and could increase the available metabolizable energy.

Oral Administration of EC-12 Increases the Baseline Gene Expression of Antiviral Cytokine Genes, IFN-γ and TNF-α, in Splenocytes and Mesenteric Lymph Node Cells of Weaning Piglets

Weaning piglets are continuously exposed to various viruses. The antiviral effects of lactic acid bacteria (LAB) have been confirmed mainly in humans and mice, while few studies have been conducted in livestock. In this study, we evaluated the effect of oral administration of Enterococcus faecalis strain EC-12 (EC-12) on the gene expressions of antiviral cytokines in weaning piglets. Piglets were allocated to the EC-12-administered group (E group) and the no-treatment control group (C group). The small intestinal tissue, the mesenteric lymph node (MLN) cells and the splenocytes were collected from the piglets. The tissue and cells were co-cultured with a live vaccine of porcine reproductive respiratory syndrome virus, porcine epidemic diarrhea virus or EC-12. After the incubation, the gene expressions of IFN-γ and TNF-α in the tissue and cells were evaluated. The gene expressions of IFN-γ in the MLN cells and TNF-α in the splenocytes were significantly higher in the E group than in the C group. However, the increase in the gene expression of antiviral cytokines was observed independently of the antigen treatments. The results of the present study suggest that oral administration of EC-12 did not increase the response of immune cells to specific viral antigens but increased the baseline gene expression of antiviral cytokines.

Correlation between villous height and the disaccharidase activity in the small intestine of piglets from nursing to growing

Early weaning induces villous atrophy in the small intestine. Reduction in villous height in the small intestine after weaning is associated with reductions in brush-border enzyme activity. Body weight gain after weaning is, therefore, correlated with villous height. This evidence suggested that the maintenance of small intestinal structure and function after weaning is important for the growth of young pigs. On the other hand, the relationship between villous height and the activity of the digestive enzymes in the small intestine has not been studied with piglets from the suckling to the growing period. Five suckling piglets, four piglets in the proximal stage of weaning, four pigs in the distal stage of weaning and four growing pigs were used. The activities of lactase (LA), sucrase (SA) and maltase (MA) were determined. LA showed a positive correlation with villous height in weaning. SA and MA were positively correlated with villous height from suckling to growing. In a previous study, non-infectious dyspeptic diarrhea was frequently observed in growing piglets on Japanese swine farms. The maintenance of villous height to retain disaccharidase activity may prevent dyspepsic diarrhea in this stage.

Triennial Growth Symposium: effects of polymeric carbohydrates on growth and development in pigs

Polymeric carbohydrates, starch and nonstarch polysaccharides (NSP), quantitatively represent the largest portion of the diets for pigs and are, therefore, the largest energy contributor. The 2 types of polysaccharides, however, have different fates and functions in the gastrointestinal tract and lead to different metabolites upon digestion. Pancreatic and mucosal enzymes in the small intestine break down the majority of starch, whereas NSP primarily are degraded by the microflora in the large intestine. Starch degradation leads to the release of glucose, which is absorbed by an active absorption process that triggers the release of insulin from the pancreas, whereas the fermentation of NSP to short-chain fatty acids (SCFA; i.e., acetate, propionate, and butyrate) occurs at a slower and more constant rate and with SCFA being absorbed by passive diffusion. Type and amounts of polymeric carbohydrates influence growth and development through different mechanisms. First, the proportion of starch to NSP plays an important role for the content of available energy (i.e., DE, ME, and NE); available energy relative to protein is crucial for performance and carcass quality. Second, the proportion of starch to NSP will influence rate and type of metabolites (i.e., glucose vs. SCFA) deriving from carbohydrate assimilation. Third and finally, the type of starch (i.e., types A, B, and C) and soluble NSP will influence the release of insulin, the hormone that facilitates nutrient uptake by tissues, organs, and cells, and thus plays a critically essential role in protein synthesis and muscle growth, as well as lipid synthesis and adipose tissue growth. In conclusion, polymeric carbohydrates influence growth and development through events in the gut and direct and indirect effects of different metabolites deriving from carbohydrate assimilation.

Effect of dietary inorganic sulfur level on growth performance, fecal composition, and measures of inflammation and sulfate-reducing bacteria in the intestine of growing pigs

Two experiments investigated the impact of dietary inorganic S on growth performance, intestinal inflammation, fecal composition, and the presence of sulfate-reducing bacteria (SRB). In Exp. 1, individually housed pigs (n = 42; 13.8 kg) were fed diets containing 2,300 or 2,100 mg/kg of S for 24 d. Decreasing dietary S had no effect on ADG, ADFI, or G:F. In Exp. 2, pigs (n = 64; 13.3 kg) were fed diets containing 0, 0.625, 1.25, 2.5, or 5.0% CaSO(4), thereby increasing dietary S from 2,900 to 12,100 mg/kg. Two additional diets were fed to confirm the lack of an impact due to feeding low dietary S on pig performance and to determine if the increased Ca and P content in the diets containing CaSO(4) had an impact on growth performance. Pigs were fed for 35 d. Ileal tissue, ileal mucosa, and colon tissue were harvested from pigs fed the 0 and 5% CaSO(4) diets (low-S and high-S, respectively) to determine the impact of dietary S on inflammation-related mRNA, activity of mucosal alkaline phosphatase and sucrase, and pathways of inflammatory activation. Real-time PCR was used to quantify SRB in ileal and colon digesta samples and feces. Fecal pH, sulfide, and ammonia concentrations were also determined. There was no impact on growth performance in pigs fed the diet reduced in dietary S or by the increase of dietary Ca and P. Increasing dietary S from 2,900 to 12,100 mg/kg had a linear (P < 0.01) effect on ADG and a cubic effect (P < 0.05) on ADFI and G:F. Real-time reverse-transcription PCR analysis revealed that pigs fed high-S increased (P < 0.05) the relative abundance of intracellular adhesion molecule-1, tumor necrosis factor-α, and suppressor of cytokine signaling-3 mRNA, and tended (P = 0.09) to increase the relative abundance of IL-6 mRNA in ileal tissue. Likewise, pigs fed high-S had reduced (P < 0.05) abundance of nuclear factor of κ light polypeptide gene enhancer in B-cells inhibitor-α and increased (P < 0.05) phospho-p44/p42 mitogen-activated protein kinase in ileal tissue, but there was no effect of dietary S on mucosal alkaline phosphatase or sucrase activity. Pigs fed the high-S diet had decreased (P < 0.05) total bacteria in ileal digesta, but increased (P < 0.05) prevalence of SRB in colon contents. Fecal sulfide was increased (P < 0.05) and fecal pH was deceased (P < 0.05) in pigs fed high-S. The data indicate that growing pigs can tolerate relatively high amounts of dietary inorganic S, but high dietary S content alters inflammatory mediators and intestinal bacteria.

Wheat starch in the diet of pigs between 7 and 28 days of age

Sixty-four pigs were given diets containing lactose or starch as the major source of carbohydrate in two separate experiments conducted between 7 and 28 days of age.

In the first experiment, pigs were offered lactose, wheat starch, wheat or extruded wheat. Performance over the whole experimental period, of pigs given lactose or wheat, was similar, but greater than that of pigs given wheat starch. Apparent digestion of wheat diets was less than that of the other diets. In the second experiment, performance of pigs given lactose or wheat was also similar over the whole experiment. However, between 7 and 14 days of age in both experiments, weight gains and food conversion ratios of pigs given wheat were less than those of pigs given lactose.

The activity of maltase and amylase in the intestinal mucosa, and amylase in the pancreas, increased between 7 and 28 days of age. The maltase and amylase activity in the intestinal mucosa and pancreas of the pigs given wheat was greater than that of the pigs given lactose, while the activity of lactase in the intestinal mucosa was greater in the pigs given diets containing lactose than in those pigs given wheat.

In a third experiment, it was found that most of the hydrolysis and absorption of starch occurred in the duodenum and jejunum of the pigs, and had been completed before the ileum.

Maintenance of villous height and crypt depth in piglets by providing continuous nutrition after weaning

Thirty-two piglets weaned at 28 days of age were used to test the hypothesis that maintenance of nutrition after weaning would prevent the normal decline in villous height and increase in crypt depth and hence preserve the structure and function of the small intestine. Piglets were allocated to one of four treatments at weaning: (1) control group killed at weaning; (2) piglets offered a dry starter diet ad libitum; (3) piglets offered ewes' fresh milk; and (4) piglets offered ewes' fresh milk plus 20 g t-glutamine per I. Piglets in treatments (3) and (4) were offered ewes' fresh milk every 2 h in a feeding schedule that increased from 1·2 I per piglet on the 1st day after weaning to 2·4 I on days 4 and 5. On the 5th day all piglets were killed and samples of small intestine were taken for histological and biochemical examination. Feeding ewes' milk or ewes' milk plus 20 g L-glutamine per I maintained (P > 0·05) villous height and crypt depth compared with piglets killed at weaning. In contrast, piglets given a dry starter diet had shorter villi (P < 0·001), deeper crypts (P < 0·001), and proportionately 0·21 to 0·28 less protein (P > 0·05) in their intestinal mucosa. Piglets given the starter diet proportionately grew from 0·49 to 0·62 more slowly (P < 0·01), ate the same amount of dry matter (DM; P > 0·05), but consumed proportionately 0·30 less energy (P < 0·001) than their counterparts given the milk diets. No treatment differences in the specific activity of lactase and sucrase were observed (P > 0·05). Significant correlations existed between voluntary food intake and villous height at the proximal jejunum for piglets given the starter diet and ewes' milk (P < 0·05 and P = 0·073, respectively). In turn, villous height was significantly correlated (r = 0·78 to 0·87, P < 0·05) with the rate of body-weight gain after weaning in these two groups. For piglets offered ewes' milk plus glutamine, an increase in DM intake was associated only with increases in crypt depth (P < 0·01). These data show that the structure and function of the small intestine can be preserved when a milk diet is given after weaning, and suggest an association between food intake and villous height in determining post-weaning weight gain.

Risk factors for post-weaning diarrhoea on piglet producing farms in Finland

Background

Post-weaning diarrhoea (PWD) is a significant gastrointestinal disease in pigs. It is considered a multifactorial disease associated with proliferation of enterotoxigenic Escherichia coli in the intestinal tract of affected pigs. The aim of this study was to analyse risk factors related to the occurrence of PWD on Finnish piglet producing farms.

Methods

The data of a follow-up study of 73 conventional piglet producing farms was used in the case-control study. The selection of the 41 PWD case and 28 control farms was based on the use of antimicrobials for treating diarrhoea in weaned pigs and the answers related to the occurrence of diarrhoea after weaning in the questionnaire. Four intermediate farms were excluded from the statistical analysis.

Altogether 39 factors related to herd characteristics, weaner pig management and pig health were studied. The median number of sows was 59.0 (IQR = 44.0; 74.5) and 52.5 (IQR = 36.8; 61.5) on the case and the control farms, respectively.

The significances of the univariable associations between the explanatory variables and the outcome variable were tested, and in the multivariate analysis quasibinomial generalized linear models were applied.

Results

An increased risk of PWD was associated with the regimen of twice a day feeding and feed restriction after weaning (P = 0.02; compared to feeding three or more meals a day or the use of ad libitum feeding) and with a higher number of sows on the farm (P = 0.02; risk increasing with increasing number of sows). Automatic temperature control was associated with a decreased risk of PWD (P = 0.03; compared to manual temperature control).

Conclusion

Twice a day feeding of newly-weaned pigs should be avoided if the amount of feed given is restricted. Variation in ambient temperature should be minimized in housing of newly-weaned pigs and this can be achieved by using automatic temperature control. With increasing number of sows in the herds the risk of PWD increases and more attention should be paid to prevention of post-weaning diarrhoea.

Vegetable proteins enhance the growth of milk-fed piglets, despite lower apparent ileal digestibility

This experiment compared the replacement of whey protein with isolated soy protein (ISP), or 2 levels of a hydrolyzed vegetable protein mixture (Lo HVPM and Hi HVPM, containing a partially hydrolyzed blend of soy, wheat, and other proteins) in liquid milk-replacer diets fed to neonatal pigs from 2 to 19 d of age. Piglets fed the vegetable protein diets weighed 20% more (8179 +/- 211 g, P < 0.05) at the end of the study than piglets fed the whey diet (6805 +/- 244 g). Growth rates were 35% higher for piglets fed the Hi HVPM diet than for piglets fed the whey diet. Similarly, intakes of the vegetable protein diets exceeded that for the whey diet (P < 0.05). Although the apparent ileal digestibilities of most amino acids were greater for the whey diet, digestible amino acid intakes (especially Arg, Phe, Met, and His) were greater in pigs fed the Hi HVPM and ISP diets (P < 0.01). Furthermore, carcasses of piglets fed the whey diet contained a higher percentage of fat and ash, whereas piglets fed the vegetable protein-containing diets accreted protein 42% faster (P < 0.01). Villus height and area and leucine aminopeptidase activity in the small intestine were greater in piglets fed the Lo HVPM diet than in those fed the ISP diet. Collectively, these data support the conclusion that some processed vegetable proteins may be good alternatives to whey protein in liquid diets formulated for neonatal pigs and that an appropriate balance of amino acids is more important than the source of protein per se.

Digestibility of carbohydrates in growing pigs: a comparison between the t-cannula and the steered ileo-caecal valve cannula

We compared the determination of ileal and total tract digestibility of carbohydrates in five experimental diets using a double 5 x 5 Latin square design involving a total of 10 cannulated pigs; half of the pigs were equipped with a simple T-cannula and the other half with steered ileo-caecal valve (SICV)-cannula. The diets consisted of nitrogen-free mixture and soya bean meal, sunflower meal, peas or rape seed cake diluted to about 180 g/kg DM protein with the nitrogen-free mixture. There was no significant difference in the digestibility values using the two types of cannulas with regard to organic matter, sugars (sum of glucose, fructose and sucrose), alpha-galactosides (sum of raffinose, stachyose and verbascose), starch, cellulose, total non-cellulosic polysaccharides (NCP) and insoluble NCP constituents. The digestibility values for the NCP residues arabinose and galactose, however, were estimated higher but with a lower variability with the SICV-cannula compared with the T-cannula. The type of cannula did no influence the estimation of the total tract digestibility for any of the major dietary constituents, but the total tract digestibility was slightly more variable when the pigs were equipped with the SICV-cannula compared with the T-cannula. There was no difference in the ileal digestibility of sugars, alpha-galactosides, cellulose and the NCP arabinose and uronic acids residues among the experimental diets, while the ileal digestibility of starch and the remaining NCP sugar residues varied between diets. The total tract digestibility was complete for sugars, alpha-galactosides and starch, whereas the digestibility of the cell wall constituents varied in accordance with the polymeric composition of the cell walls. It was concluded that ileal digesta samples from SICV-cannula are more homogenous than those from the T-cannula. In cases where the precision of each determination is crucial, the SICV-cannula should be the option.

Effects of sources of protein and enzyme supplementation on protein digestibility and chyme characteristics in broilers

1. The purpose of this study was to evaluate the effects of protein source and enzyme supplementation on protein digestibility and chyme characteristics in broilers. 2. One hundred and twenty growing (13 d old) and 60 finishing (34 d old) Arbor Acre strain commercial male broilers were selected and placed into individual metabolic cages. 3. The experiment was a 5 x 2 factorial arrangement with 5 different sources of protein: casein, fish meal, soybean meal (SBM), soy protein concentrate (SPC), maize gluten meal (MGM) and two levels of protease (bromelain), 0 and 65 CDU/kg diets. 4. The diets were iso-nitrogenous and semi-purified, with Cr2O3 as an indicator for determination of ileal digestibility and chyme characteristics. 5. Apparent ileal protein digestibility (AIPD) in both growing and finishing chickens was highest on the casein diet, followed by fish meal, SBM, SPC and MGM. 6. Enzyme inclusion did not improve protein digestibility, but significantly decreased the digesta pH value in the gizzard and increased pH in the ileum in the 3-week-old broilers. 7. The digesta pH values in the gizzard and duodenum were significantly lower in the SBM and fish meal groups compared with the other protein groups. The molecular weight distribution pattern of the soluble protein in the chyme of the gastrointestinal (GI) segments showed a similar trend, regardless of the enzyme inclusion or the stage of growth. 8. The molecular weight profile of soluble protein changed dynamically in the casein fed broilers from the gizzard to ileum and the low molecular weight proteins, < 7 kDa, reached maximum levels at the ileum. The molecular weight profile of the soluble protein in the SBM and SPC changed between the jejunum and the ileum and in the intermediate molecular soluble protein weight (7 to 10 kDa) was significantly decreased. This indicated that the hydrolysis process began from the middle to the posterior end of the small intestine. 9. Similar profiles were also shown with fish meal protein. The pattern of distribution, however, did not show any prominent change in the GI segments of the MGM group. 10. The pepsin, trypsin and chymotrypsin protease activity in the gizzard and duodenum were highest in the casein group and lowest in the MGM group as compared with the other protein groups. 11. The rate change in the patterns of molecular weight distribution in soluble protein and the digestive enzyme activity provide indications of the partial digestibility of different protein sources. The exogenous enzyme, bromelain, did not show any beneficial effect on protein digestion.

Small intestinal morphology and disaccharidase activities in early-weaned piglets fed a diet containing spray-dried porcine plasma

The purpose of this study was to test whether dietary spray-dried porcine plasma (SDPP) in early-weaned piglets prevents small intestinal villus atrophy by trophic or protective activity. Fifty-four weaned, 18-day-old piglets were used to determine the effect of dietary SDPP on small intestinal villus length, crypt depth, enterocyt mitotic activity and brush border enzyme activities during the first week after weaning. The piglets were offered a diet containing either 8% SDPP or 8% casein. At 2 and 7 days after weaning, piglets were anaesthetized to provide samples of the small intestinal wall and killed immediately afterwards. There were no differences in daily gain and daily feed intake between the two dietary treatments. At day 2 after weaning, all piglets showed a marked reduction in villus height when compared with baseline values. In all piglets, small intestinal enterocyte mitotic activity had decreased by day 2 and was increased again on day 7. There were no significant effects of dietary SDPP on small intestinal villus length, crypt depth and enterocyt mitotic activity. This indicates that SDPP has no trophic effect on the small intestinal mucosa and that it does not protect against the damaging effect on the small intestinal villi that is associated with the process of weaning. There was no effect of SDPP on lactase-, sucrase- or maltase-specific activities that are a measure of the digestive function of the small intestine. It can be concluded that SDPP versus casein has no effect on small intestinal morphology and disaccharidase activities in early weaned piglets kept under low infection pressure.

Chapter 16 Production and gene expression of brush border disaccharidases and peptidases during development in pigs and calves

This chapter reviews the expression of intestinal brush-border disaccharidases (maltase-glucoamylase, sucrase-isomaltase, lactase, and trehalase) and peptidases (aminopeptidases A and N and dipeptidyl peptidase IV) during development in growing animals. It describes the roles of intestinal enzymes, focussing on complementarity with salivary, gastric, and pancreatic digestive enzymes and their hydrolytic function in the process of absorption. Gene expression of the enzymes and nutritional regulation of their expression appear during postnatal development up to maturity. After translation of the specific mRNA, a single precursor of maltaseglucoamylase (pro-MG), rich in mannose, is produced in the rough endoplasmic reticulum (RER). In contrast to the relatively small number of carbohydrases, the number of peptidases found in enterocytes in the small intestine is large, because of the large number of different peptide bonds in oligopeptides produced by the action of pancreatic proteases. The digestive function (disaccharidase and peptidase activities) of the enterocytes and their microvilli begins when structural differentiation is complete, that is, during the period of migration over the cryptvillus junction. Modern techniques and investigations are expected to yield relevant data for elaborating feeding strategies that take into account the complex interactions between the diet, the microflora, the luminal milieu and the physiology of the small intestine, including the optimal functioning of the immunological and endocrine systems.

Does increased crypt cell proliferation impair cholesterol absorption after proximal gut resection?

BACKGROUND

The effects of proximal small-bowel resection on absorption and synthesis of cholesterol are unclear.

METHODS

To study cholesterol absorption and synthesis after proximal gut resections of variable length, plasma plant sterols, cholestanol, and cholesterol precursors were measured 1 and 2 months after 50% and 75% proximal small-bowel resection or transection. To examine the effect of increased crypt cell proliferation and brush border development on cholesterol absorption, the results were related to the mucosal morphology, crypt cell proliferation, and disaccharidase activities of the remaining small bowel.

RESULTS

Campesterol levels in proportion to cholesterol decreased markedly more, and those of cholestanol markedly less, than would be expected simply due to the amount of proximal small intestine removed, whereas sitosterol proportions decreased in proportion to the length of gut resection. Campesterol proportions markedly (P = 0.06) increased between 1 and 2 months after 50% resection but remained unchanged after 75% resection. Crypt cell proliferation was only increased in the 75% resection group (P < 0.05). The longer the proximal gut resection, the lower was the mucosal enzyme activity. Both resection groups showed increased plasma cholesterol precursor proportions and crypt depth (P < 0.05), whereas villus height remained unchanged. After massive proximal resection campesterol and sitosterol proportions were inversely related to crypt cell proliferation (r = -0.86-0.83, P < 0.01).

CONCLUSIONS

Increased crypt cell proliferation activated by massive proximal gut resection may act as a previously unrecognized factor in aggravating cholesterol malabsorption and retarding its recovery during the early postoperative period. These findings warrant further investigation.

Effect of different sources of dietary fibre on growth performance, intestinal morphology and caecal carbohydrases of domestic geese

1. The aim of this study was to examine the effects of dietary fibre sources on growth and on the development of the gastro-intestinal tract in growing geese. 2. Six-week-old female White Roman geese were divided at random into 6 groups with 6 dietary treatments. Diets were isoenergetic and isonitrogenous and contained alfalfa meal, barley bran, rice hulls, cellulose, pectin or lignin as the major dietary source of fibre. 3. Food intake was significantly higher in the barley bran group than in the other groups. Both daily weight gain and food conversion of the pectin and alfalfa meal groups were lower than those of the other groups. 4. In the 9-week-old geese, the relative weight and the length of the small intestine did not significantly differ among treatment groups. However, the relative weight was significantly lightest and the caecal length was significantly shortest (P < 0.05) in the pectin group. 5. Activities of amylase and cellulose hydrolases of the caecal contents were also highest in the pectin group. 6. From SEM micrographs, no morphological damage of the villi was observable in the different intestinal segments of the geese in any of the treatments.

Intestinal adaptation after massive proximal small-bowel resection in the pig

BACKGROUND

Small-intestinal adaptation to resection has been extensively studied in rats. The present study investigates morphology, crypt cell proliferation, and disaccharidase activities of the remaining small intestine and colon after 75% proximal resection of porcine small intestine.

METHODS

Specimens were obtained from the proximal jejunum, middle and distal ileum, and proximal colon preoperatively (n = 5) and 14 weeks after small-bowel transection (n = 5) or resection (n = 5). Proliferation was analyzed immunohistochemically with the Ki-67 antigen MIB-1. Disaccharidase activities were determined in accordance with the method of Dahlqvist.

RESULTS

In addition to macroscopic enlargement, resection markedly increased the villi and crypts of the remaining small bowel. Crypt cell proliferation decreased with advancing age after transection but remained at the preoperative level after resection. Specific, but not total, activities of maltase and sucrase in the mid-ileum decreased after resection.

CONCLUSION

Small-intestinal adaptation in the pig involves macroscopic enlargement and a prompt increase in villus size, which is associated with high crypt cell proliferation.

Maintenance of villus height and crypt depth, and enhancement of disaccharide digestion and monosaccharide absorption, in piglets fed on cows' whole milk after weaning

The aims of the present study were (a) to maintain the structure and function of the small intestine of the piglet after weaning, and (b) to compare the capacity in vivo of sucking and weaned piglets to digest oral boluses of lactose and sucrose and absorb their monosaccharide products. Piglets were fed on cows' whole milk ad libitum every 2 h for 5 d after weaning. Physiological doses of lactose plus fructose (treatment LAC+FRU) and sucrose plus galactose (treatment SUC+GAL) were administered on day 27 of lactation and on the fifth day after weaning, after which time piglets were killed. Villus height and crypt depth were maintained (P > 0.05) by feeding cows' milk after weaning. The areas under the curves (AUC) for galactose and glucose, adjusted for live weight and plasma volume, increased (P < 0.05) after weaning. Despite the enhancement of gut function after weaning, the galactose index (GalI:AUC for galactose ingested as lactose divided by the AUC for the same dose of galactose ingested as the monosaccharide) and fructose index (FruI: AUC for fructose ingested as sucrose divided by the AUC for the same dose of fructose ingested as the monosaccharide), which are indices of digestive and absorptive efficiency, both decreased after weaning. This apparent anomaly may be reconciled by increased growth, and hence surface area, of the small intestine between weaning and slaughter such that 'total' digestion and absorption most probably increased despite apparent decreases in GalI and FruI. Positive correlations (P < 0.05) between villus height and GalI are consistent with the maximum activity of lactase occurring more apically along the villus. Significant linear relationships (P < 0.05) were recorded between villus height at the proximal jejunum and adjusted AUC for galactose and glucose following treatment LAC+FRU, and between villus height at the proximal jejunum and adjusted glucose AUC following treatment SUC+GAL. These relationships suggest that maximum digestion and absorption occurs at increasing distances along the crypt:villus axis in the weaned pig.

Enhancement of intestinal hydrolysis of lactose by microbial beta-galactosidase (EC 3.2.1.23) of kefir

The effect of microbial beta-galactosidase (EC 3.2.1.23) activity on intestinal lactose digestion was estimated directly by following post-prandial venous plasma galactose concentrations. To avoid superimposing effects of free galactose, as with yogurt, fresh or heat-treated suspensions of mechanically disintegrated kefir grains in kefir, containing lactose but no free galactose, were fed to ten Göttingen minipigs. Each meal contained 101.1 (SEM 0.1) mmol lactose in kefir supplemented by either native or heat-treated kefir grains corresponding to a mean beta-galactosidase activity of either 72 (SEM 8) U or zero. Feeding kefir with beta-galactosidase activity resulted in a 30% enhancement of the mean post-prandial plasma galactose peak concentration from 33 (SEM 7) to 43 (SEM 12) mumol/l (n 10), as well as in 23% greater mean areas under the galactose-response curves (8.1 (SEM 1.5) v. 6.6 (SEM 1.2) mmol/min per l) if compared with kefir with heat-treated grains. Both differences were significant (P less than 0.05; paired Wilcoxon test by ranks). There was no induction of intestinal beta-galactosidase (EC 3.2.1.108) activity or intestinal lactose-hydrolysing bacteria by lactose feeding. These results give direct evidence of an enhanced lactose digestion and absorption in native fermented milk products due to the microbial beta-galactosidase activity.

Influence of virginiamycin on the digestive physiology in precaecal re-entrant cannulated pigs

The present experiment was set up to study the effect of Virginiamycin, a nutritional growth promoting antibiotic, on the digestive physiology using precaecal cannulated pigs. The semipurified diet used provided 21% protein and 60% of nitrogen free extract (NFE), 2/3 as starch and 1/3 as lactose. Due the older age of the pigs, the lactose induced some degree of malabsorption as precaecal flow rate of digesta was markedly higher (3.2 kg/d) compared with published data obtained with purified diets without lactose. This was also reflected in the rather low ileal digestibility of the nutrients (%): dry matter 68.6, protein 79.6, fat 78.4 and NFE 75.0. Virginiamycin markedly lowered flow rate (2.2 kg/d) and significantly improved apparent precaecal digestibilities (%): dry matter 74.0, protein 81.4, fat 81.9 and NFE 78.7. The faecal apparent digestibility was comparable with published data. There were no treatment differences indicating that precaecal digestibilities are much more sensitive then faecal ones. In order to explain the differences obtained the mean retention time in the upper intestine was measured. Although significant differences were noted (control: 5 h, Virginiamycin: 6 h) a direct cause-effect relationship was not evident. Also the activity of selected pancreatic enzymes in ileal contents was compared. There were no consistent differences between the two treatments, except for a lower lipase activity during Virginiamycin treatment.

Effect of lactation on the decline of brush border lactase activity in neonatal pigs

It has been shown that during the early phase of lactation porcine milk contains high concentrations of hormones and growth factors. The aim of the present investigation was to examine the hypothesis that the temporal coordination of intestinal maturation in piglets can be extrinsically regulated through changes in the composition of milk during the suckling period. Gut morphology and the ontogeny of brush border lactase activity were investigated in piglets reared on two suckling regimens designed to expose the animals to compositionally distinct milk. The first group of animals were cross-fostered onto postcolostrum sows and thereafter suckled normally for up to eight weeks. These normally suckled (N) animals consequently received both early and late lactation products. The second group of piglets were cross-fostered each week, for up to eight weeks, onto newly farrowed sows which were postcolostrum. As a result of this repeated cross-fostering (CF) these animals received only early lactation products. Animals were sacrificed at one, three, five, seven, and eight weeks postpartum. Biochemically active lactase decreased significantly (p less than 0.001) in both groups over eight weeks, but the rate of loss of activity was greater in the CF animals than in the N pigs by approximately 50% at week 3 and 25% at week 8. Quantitative histochemical analysis of lactase activity corroborated the biochemical data. At three weeks maximal enzyme activity was observed approximately 400 microns from the villus/crypt junction. Histochemically detected lactase decreased throughout the suckling period, but the intensity of reaction product was consistently weaker over the entire villus surface in the CF animals. Immunocytochemically detectable lactase was identified at the same sites as the histochemical reaction products. In addition, immunofluorescence microscopy showed the presence of histochemically undetectable enzyme on the basolateral and brush border membranes of both villus and crypt cells. Villus/crypt ratios were significantly lower (p<0.001) in the CF animals than in the N pigs between weeks 3 and 5. The results of this study suggest that lactation products can accelerate the loss of brush border lactase activity. The observed decline in biochemically and histochemically detected lactase was considered to be a consequence of reduced enterocyte lifespan, decreased synthesis of enzyme protein, or altered post-translational modification of enzyme protein, or a combination of there.

Digestive development of the early-weaned pig. 2. Effect of level of food intake on digestive enzyme activity during the immediate post-weaning period

Gastric intubation was adopted as a means of comparing the effect of two feeding levels, continuous nutrient supply (C) and restricted nutrient supply (R), on the digestive development of pigs weaned at 14 d of age, during the first 5 d post-weaning. The absolute weights of the stomach and the pancreas were significantly greater (P less than 0.001) in C compared with R pigs. The effect was not significant for pancreas weight when expressed per kg body-weight but was significant (P less than 0.05) for stomach weight. The weights of the small intestine (SI), SI mucosa and total mucosal protein were significantly higher (P less than 0.001) in C pigs but protein content per g mucosa was similar in the C and R groups. There was no significant effect of treatment on the activity of lactase (beta-glucosidase; EC 3.2.1.23) or sucrase (sucrose-alpha-glucosidase; EC 3.2.1.48) irrespective of the basis of comparison used. The specific activity (mumol/min per g protein) of maltase (alpha-glucosidase; EC 3.2.1.20) and of glucoamylase (glucan-1,4-alpha-glucosidase; EC 3.2.1.3) were similar in C and R groups but activities of maltase (mumol/g mucosa) (P less than 0.05), and maltase and glucoamylase (mol/d) (P less than 0.01) were significantly higher in C pigs. Villous height and crypt depth were significantly greater in C pigs (P less than 0.001 and P less than 0.05 respectively). Enteroglucagon was significantly (P less than 0.05) higher in C compared with R pigs. Xylose absorption and the digestibility of energy were not affected by treatment. Digestibility of dry matter, organic matter, crude protein (nitrogen x 6.25) and carbohydrate were significantly higher (P less than 0.001, P less than 0.01, P less than 0.05 and P less than 0.001 respectively) in R pigs compared with C pigs but the differences were small, ranging from 1.3 to 2.5%. These results demonstrate that (1) nutrient intake in the weaned pig affects the anatomy, morphology and function of the gut, (2) there is considerable 'spare capacity' for digestion of cereal-based diets even in pigs weaned at 14 d of age, (3) measurements in vitro of digestive function are of limited value unless supported by information in vivo on absorption/digestibility.

Digestive development of the early-weaned pig. 1. Effect of continuous nutrient supply on the development of the digestive tract and on changes in digestive enzyme activity during the first week post-weaning

Gastric intubation was adopted to examine the effect of continuous nutrient supply on digestive development of the pig during the immediate post-weaning period. The 14 d-weaned animals were slaughtered at 3, 5 and 7 d post-weaning (3W, 5W and 7W respectively) and the suckled animals were slaughtered at 14 and 22 d of age (14SR and 22SR respectively). The weight of the pancreas (g/kg bodyweight) was significantly greater (P less than 0.05) in the 5W and 7W groups, as was the weight of large intestine (g/kg) in all weaned groups (P less than 0.01) compared with sow-reared pigs. The stomach weight (g/kg) tended to be greater in the weaned groups. Weaning, in conjunction with a continuous nutrient supply, did not significantly alter the time-related changes in the weight of the small intestine (SI) or the SI mucosa, although both variables tended to be lowest in the 3W group. However, there was a 20% reduction in the protein content of the mucosa within the first 3 d post-weaning (P less than 0.01) which persisted during the 7 d experimental period. Lactase, (beta-galactosidase; EC 3.2.1.23) activity (mumol/g protein and mol/d) of the 7W group was reduced to approximately 40% of the 22SR value. Hence, continuous nutrient supply may have delayed, but did not prevent, the loss of lactase activity at weaning. The activity of sucrase (sucrose-alpha-glucosidase; EC 3.2.1.48) was significantly higher in 22SR compared with 14SR animals. Sucrase activity in weaned pigs was intermediate to the values for sow-reared pigs whereas maltase (alpha-glucosidase; EC 3.2.1.20) and glucoamylase (glucan 1,4-alpha-glucosidase; EC 3.2.1.3) were significantly increased in relation to their sow-reared counterparts. Continuous nutrient supply did not prevent the reduction in villous height and the crypt hypertrophy associated with weaning. The results of the present study suggest that there may be some degree of interaction between nutrient intake and gut development during the immediate post-weaning period but that there is also a component of the adaptive response which is independent of nutrient intake. They confirm the rapid substrate induction of the brush-border glucoamylases and indicate the importance of considering total as well as specific enzyme activity for satisfactory interpretation of changes in digestive function.

The influence of inclusion of either an antibiotic or a probiotic in the diet on the development of digestive enzyme activity in the pig

The aim of the present experiment was to determine the influence of either probiotic or antibiotic inclusion in the diets of pigs from birth on the development of enzyme activity in the small intestine. Pigs were fed on creep feed and grower diets containing either a probiotic, an antibiotic or no added growth promoter. At 7, 17, 42 and 80 d of age pigs from each treatment group were sampled to investigate the development of carbohydrase and peptidase activity in the mucosa at five sites along the small intestine. Inclusion of either the probiotic or antibiotic had a significant effect on the development of sucrase (sucrose alpha-D-glucohydrolase; EC 3.2.1.48), lactase (beta-D-galactoside galactohydrolase; EC 3.2.1.23) and tripeptidase (EC 3.4.11.4) activities before weaning but had no effect on depeptidase (EC 3.14.13.11) activity. The study of the distribution of enzyme activity along the small intestine showed significant differences between the proximal and distal sections associated with weaning.

Brush border membrane sucrase-isomaltase, maltase-glucoamylase and trehalase in mammals. Comparative development, effects of glucocorticoids, molecular mechanisms, and phylogenetic implications

1. Trehalase, sucrase-isomaltase and maltase-glucoamylase are three integral glycoproteins of the brush border membranes of the enterocytes. On the basis of a comparative study on alpha-glycosidase activities (sucrase, isomaltase, maltase, glucoamylase and trehalase) associated to these glycoproteins during neonatal development, mammals could be basically divided into three groups. 2. In rodents and rabbit alpha-glycosidase activities are low or undetectable during the suckling period and increase to adult levels during the weaning period. In cat, dog and the primates examined, alpha-glycosidase activities are well or fully developed at birth. 3. In ruminants and pinnipedia alpha-glycosidases are low or absent throughout life. 4. During the suckling period of rat, mouse and rabbit, glucocorticoids trigger a premature and dramatic increase of all alpha-glycosidases. 5. On the contrary, alpha-glycosidases development during the weaning period appears to be independent of glucocorticoids. Neither hypophysectomy nor adrenalectomy prevent the development of alpha-glycosidases; only the rate of increase is reduced. 6. Transplantations of intestinal isografts either in adult or suckling animal, have shown that (1) no systemic factor inhibits the expression of alpha-glycosidase, (2) alpha-glycosidases induction is neither triggered by luminal alimentary substances, nor by hormones, (3) alpha-glycosidase development is controlled by an intrinsic ontogenic program. 7. The use of an antiglucocorticoid failed to inhibit the spontaneous development of alpha-glycosidase activities. 8. The increase of maltase and sucrase activities triggered by glucocorticoids is associated with an increase of the concentration of two glycoproteins in the microvillous membrane: sucrase-isomaltase and maltase-glucoamylase. 9. After administration of glucocorticoids the increase of maltase, sucrase and trehalase is strongly inhibited by actinomycin-D and the increase of sucrase activity is associated with a parallel increase of sucrase-isomaltase mRNA. Transcription is most likely the primary site of control of alpha-glycosidase biosynthesis. 10. In the crypt cells, alpha-glycosidases biosynthesis appears to be triggered by a receptor-mediated glucocorticoid interaction. 11. The enterocytes synthesize more alpha-glycosidase molecules as they travel to the tip of the villi. 12. The simultaneous, biosynthesis of sucrase-isomaltase and maltase-glucoamylase triggered by glucocorticoids, as well as their simultaneous normal development suggest that they may be subjected to related control mechanisms. 13. It is suggested that sucrase-isomaltase and maltase-glucoamylase might have arisen by several cycles of partial gene duplication of an ancestor gene coding for a single site maltase-isomaltase; subsequent mutation would have transformed isomaltase into sucrase or glucoamylase.