Developmental patterns of intestinal transport mechanisms in the chick

Effects of deoxynivalenol on general performance and electrophysiological properties of intestinal mucosa of broiler chickens

A feeding trial was conducted to evaluate the effects of diets contaminated with deoxynivalenol (DON on the performance of broilers and on the electro-physiological parameters of the gut. The control group was fed the starter and finisher diets without addition of DON. Another group of broilers was fed the starter and finisher diets with 10 mg/kg DON, whereas another group was fed the DON-contaminated diets supplemented with a microbial feed additive (Eubacterium sp.). The diets were provided ad libitum for 6 wk. DON had no effect (P > 0.05) on feed consumption, feed conversion, or body weight. The effect of DON on the electrophysiological parameters of the jejunum was studied in vitro using isolated gut mucosa in Ussing chambers. At the end of the feeding period, 7 birds from each group were killed, and the basal and glucose stimulated transmural potential difference (PD), short-circuit current (Isc), and electrical resistance (R) were measured in the isolated gut mucosa to characterize the electrical properties of the gut. The transmural PD did not differ (P > 0.05) among groups. The tissue resistance was greater (P < 0.05) in birds receiving DON and the microbial feed additive than in the controls and DON group. Addition of D-glucose on the luminal side of the isolated mucosa increased (P < 0.05) Isc in the control and DON-probiotic (Eubacterium sp.; PB) groups, whereas it decreased (P < 0.05) in the DON group indicating that the glucose-induced Isc was altered by DON. Addition of the eubacteria to the DON contaminated feed of the broilers led to electrophysiological properties in the gut that were comparable with those of the control group. It could be concluded that 10 mg/kg DON in the diet impaired the Na(+)-D-glucose cotransport in the jejunum of broilers. In the absence of clinical signs, and without impaired performance, DON appeared to alter the gut function of broilers. The addition of Eubacterium sp. may be useful in counteracting the toxic effects of DON on intestinal glucose transport.

Stunting syndrome in broilers: effect of electrolytes in drinking water on performance and intestinal glucose transport

Posthatched naive or inoculated male broiler chicks were kept in separate rooms. An inoculum was prepared from intestines of stunting-syndrome affected broiler chicks. Tap water was supplied from 2 L cups, 1 cup per pen. In the Ist experiment, the naive chicks were provided with tap water only and the inoculated ones had free access to tap water or to an electrolyte solution. In the 2nd experiment, the naive and inoculated birds had free access to water in addition to an electrolyte solution. Supplementation was provided up to 3 weeks of age; thereafter all chicks had access to tap water only. Water or electrolyte consumption and body weight (BW) were determined. Total water intake of inoculated chicks was higher than that of naive counterparts (P<0.001). Electrolyte supplementation increased drinking (P<0.001) in inoculated birds more than in naive ones. At 1 week old the weight of the inoculated birds was about 64% of the weight of naive ones; at the age of 4 and 6 weeks it was about 74% and 86% respectively. Compensatory growth was most apparent in the inoculated chicks provided with electrolyte solution. At the age of 6 weeks, the latter exceeded the BW of the exclusively water supplied counterparts by 327 g. Electrolyte supplementation up to the age of 3 weeks had no effect on the naive counterparts. Osmolality was reduced slightly, but very significantly by inoculation; electrolyte supply had no effect on this variable. Sodium concentration in the plasma was higher in the inoculated birds. Plasma albumin was markedly reduced by inoculation on weeks 1 and 2. Whereas the inoculated chicks supplied with electrolytes resumed the level plasma albumin level of the naive chicks on week 3, an over-compensation occurred in the inoculated-water-supplied (IW) group, and they surpassed the naive chicks significantly. Blood hematocrit increased significantly with age; inoculation, age and/or electrolyte supplementation had no effect on this variable. Sodium-dependent glucose transport rates were enhanced in vesicles obtained from inoculated chicks as compared to naive ones. While electrolyte supplementation had no effect on glucose active transport in naive chicks, electrolyte supplementation decreased rates of glucose active transport in inoculated ones. These data demonstrate that electrolyte supplementation during the early age may be used to enhance the tolerance of broiler chicks to stunting-syndrome by improving food and water consumption, and subsequently growth rate during and after cessation of electrolyte supply.

Developmental study of alpha-methyl-D-glucoside and L-proline uptake in the small intestine of the White Leghorn chicken

Development changes in alpha-methyl-D-glucoside and L-proline accumulation were studied using everted sleeves from the duodenum, jejunum, and ileum of chickens. Six age groups of chickens were used: 1 d and 1, 2, 3, 5 to 6, and 12 to 14 wk. Our results showed the presence of a Na+-dependent mechanism of sugar and amino acid uptake that is already fully developed at hatch. The intestinal transport activity undergoes substantial changes with age and region studied. Intracellular accumulation of alpha-methyl-D-glucoside and L-proline was greater in newly hatched chicks and then declined with age in the three regions of the small intestine, except for L-proline transport in ileum, which remained constant during the period studied. The transport mechanisms for each nutrient followed separate developmental patterns along the small intestine during the period studied.

L-leucine intestinal transport at different ages in chicken: effect of anticoccidial drugs

1. L-Leucine transport by everted slices of duodenum, jejunum ileum and cecum of 1-, 2- and 3-week-old chickens has been determined. 2. The effects of the administration with the diet of three anticoccidial drugs: monensin, maduromicin ammonium and nicarbazine have been studied. 3. In the control animals, there is a reduction on intestinal transport with age, except in the duodenum which is not age-dependent. 4. Momensine induces an increase on leucine transport in the duodenum and cecum at all ages studied and only in the 3-week-old animals in the jejunum and ileum. 5. Nicarbazine reduces jejunal absorption of leucine and does not affect the function of the other segments. 6. Maduromicin ammonium has almost no effect on the absorptive process.

Age influences on amino acid intestinal transport

1. Intestinal absorption of amino acids show a decrease with aging in different animal species such as avians, rodents and ruminants. 2. The different intestinal segments show different absorptive capacities, the jejunum being the most absorbent. 3. Chickens show the biggest capacity for amino acid absorption close to hatching. 4. In rodents the third week seems to be the period of increased transport capacity.

Role of exchange transport in the absorption of L-tryptophan in the small intestine of chicks

1. In in vitro experiments with accumulating mucosal preparations (AMP) and everted intestinal sacs, as well as in in vivo experiments with isolated loops of the small intestine the stimulating effect of a number of amino acids on L-tryptophan uptake was investigated. 2. Under "switched off" active transport (anoxia, 2,4-DNF treatment, sodium ion replacement by lithium ions in the mucosal solution) an expressed stimulation of L-tryptophan transport was observed within the mucosa and across the wall of the small intestine in the presence of L-proline, glycine, L-alpha-alanine, L-histidine and L-lysine. 3. Preincubation of AMP in the solutions of glycine, L-alpha-alanine and L-lysine was characterized by a stimulation of L-tryptophan transport, and the increase of its concentration in tissue was accompanied by the exit of an equivalent amount of glycine from it. 4. These observations show the participation of exchange transport in the uptake of L-tryptophan in the small intestine of chicks. 5. The mechanism of exchange transport in chicks starts to function on the 25th day after hatching and its intensity depends on the character of amino acid-modifier participating in the process. 6. Maximum activity of the exchange transport of L-tryptophan is demonstrated in the middle ileum. 7. L-alpha-Alanine stimulates the absorption of L-tryptophan from the isolated intestinal loop proving the existence of an exchange transport mechanism in a living organism. 8. An increased intensity of exchange transport is observed when feeding chicks with diets deficient and enriched in tryptophan.

Cell membrane amino acid transport processes in the domestic fowl (Gallus domesticus)

Intestinal absorption of amino acids in the chicken occurs by way of processes which are concentrative, Na+-dependent and dependent upon metabolic energy in the form of ATP. Intestinal transport is carrier-mediated, subject to exchange transport (trans-membrane effects) and is inhibitable by sugars, reagents which inactivate sulfhydryl groups, potassium ion, and by deoxpyridoxine, an anti-vitamin B6 agent. It is stimulated by phlorizin, a potent inhibitor of sugar transport, and in Na+-leached tissue by modifiers of tissue cyclic AMP levels, e.g. theophylline, histamine, carbachol and secretin. Separate transport sites with broad, overlapping specificities function in the intestinal absorption of the various classes of common amino acids. A simple model for these sites includes one for leucine and other neutral amino acids, one for proline, beta-alanine and related imino and amino acids, one for basic amino acids, and one for acidic amino acids. Absorption of amino acids appears to be widespread in occurrence in the digestive tract of the domestic fowl; transport has been reported to be present in the crop, gizzard, proventriculus, small intestine and in the colon. By the end of the first week of life post-hatch, the caecum loses its ability to transport. Similarly, the yolk sac loses its ability by the second day post-hatch. Intestinal transport was noted before hatch and was found to be maximal immediately post-hatch. A requirement for Ca2+ appears to be lost after the first week of life post-hatch. The cationic amino acids appear to be reabsorbed by a common mechanism in the kidney. Transport rates of leucine measured in the intestine or in the erythrocyte were found to cluster about discrete values when many individual chickens were surveyed; such patterns may be an expression of gene differences between individuals. Two lines of chickens have been developed, one high and the other low uptake, through selective breeding based on the ability of individual birds to absorb leucine in erythrocytes. High leucine absorbing chickens were found to be more effective in absorbing lysine and glycine, were more effectively stimulated by Na+, had greater erythrocyte Na+, K+-ATPase activity, and their erythrocytes contained about 20% less Na+ than low line erythrocytes. The underlying genetic difference between these lines may reside at the level of the Na+, K+-ATPase and (or) with a regulatory gene determining carrier copies. Amino acid transport in erythrocytes was noted to be highest in pre-hatch chicks and to diminish during post-hatch development.(ABSTRACT TRUNCATED AT 400 WORDS)

Changes in intestinal galactose and leucine transport during development in the chick: effect of low external calcium

There is some controversy in the literature as to the changes in sugar and amino acid absorption capacity by chicks during intestinal development in the posthatching period. For this reason, the transport of 5mM D-galactose and 4 mM L-leucine was studied in the mild intestine of the developing chick (range: 1 day to 35 days after hatch). In everted sacs, the net transepithelial transport of both substrates was maximal in the 1 to 3 days period and then it declined over the next 4 weeks. The final serosal:mucosal concentration ratio for galactose was 3.58 in 1 to 3-day-old chicks and fell to 1.62 in 26 to 30-day-old birds, while for leucine it fell from 3.52 to 1.50 in the same period. In intestinal rings from 1-day-old chicks, the uptake of 1 mM galactose after 1 min incubation was four times greater than in older animals. When the external calcium concentration was reduced from 2.5 mM (controls) to .1 mM the transport of galactose and leucine was markedly reduced: galactose transport was inhibited by 68 to 57% in 1 to 28-day-old chicks; leucine transport was inhibited by 82 to 50% in 1 to 7-day-old chicks with no significant effect thereafter.