A radiographic study of urine flow in the domestic fowl

Phylogeny and herbivory are related to avian cecal size

Avian ceca, a pair of blind sacs arising from the junction of the ileum and colon, are homologous to the cecum in mammals. Cecal size is hypothesized to depend on dietary proclivities and pressures, with faunivorous species having short ceca, whereas herbivorous species have long ceca. Previous tests of this hypothesis, however, did not account for phylogenetic pseudoreplication among closely related taxa. We collated published data on cecal length, dietary category, flying ability, and body mass from 155 avian taxa. Character states were mapped onto a phylogenetic framework, and the permutation tail probability test was used to detect phylogenetic signal in each character. Phylogenetic signal is significant among the characters. As with the cecoappendicular complex in mammals, closely-related birds tend to have similar cecal length. To account for phylogenetic pseudoreplication, we performed phylogenetic generalized least squares regression on cecal length and body mass with dietary category, superordinal-level clade, and flying ability as cofactors. The best-fitting regression model supports the dietary hypothesis for the avian cecum. Among sampled birds of comparable body mass, mean cecal length is significantly longer in herbivorous species than in carnivorous ones (p = 0.008), presumably allowing the extraction of nutrients without the burden of fermenting bulky masses of dietary fiber. Exceptions to this trend, however, suggest that avian ceca are functionally complex and may have additional roles in water balance and nitrogen recycling.

Quantification of parasite shedding and horizontal transmission parameters in Histomonas meleagridis-infected turkeys determined by real-time quantitative PCR

To gain more insight into the within flock transmission of Histomonas meleagridis, the shedding of parasites was quantified by a newly developed real-time quantitative (q)PCR and the basic reproduction number (R0) and the mean number of secondary infections per infectious bird per day in a susceptible population (β) of H. meleagridis in the absence of heterakis were assessed. Forty turkeys were divided into two groups of 10 and 30 birds at 14 days of age. Birds of the first group were inoculated with 200,000 histomonads each, the second group served as a susceptible contact group. Cloacal swabs were taken at -1, 1, 4, 7, 9, 11, 14, 18 and 21 days post inoculation (p.i.) to assess the shedding of the parasite by the qPCR (detection limit 330 histomonads/ml droppings). The experiment ended at 28 days p.i. Mortality was 100% in the inoculated birds and started at day 12 p.i., while in the contacts, it was 83% and started at 16 days p.i. Shedding started 1 day after the inoculation in both groups. The mean shedding levels (and 95% CI) expressed as parasite equivalents per gram cloacal content on a log10 scale in the inoculated, contact birds that died and contact birds alive were 2.0 (1.6-2.4), 1.6 (1.4-1.9) and 1.2 (0.5-2.0), respectively. Birds that died shed histomonas more often and were infectious for 13.4 days; in contrast, those that recovered were infectious for 5.7 days. R0 was estimated to be 8.4 and β 0.70. Simulations made with the parameters obtained were in agreement with the experimental results, confirming their validity.

Spatiotemporal mapping of the motility of the isolated chicken caecum

We studied the caecal contractile activity of the chicken (Gallus gallus) using single caeca that had been cannulated at their proximal and distal ends, and in paired caeca, maintained in situ on excised segments of gut that were cannulated at the colonic and small intestinal ends. Longitudinal and circular contractile patterns were characterised using high-definition spatiotemporal mapping. Low amplitude longitudinal contraction waves of frequency 14.1 cycles/min occurred in the absence of major contractile events. These were termed fast phasic and appeared to be mediated by slow waves. The nature of major spontaneous contractions occurring in the single caecum varied with the level of caecal distension. Type A contractions occurred when the caecum was not distended, originated from variable sites and propagated in both directions. Type B or C contractile events occurred when the caecum was moderately or fully distended, originated from a predominantly distal site and propagated proximally. On diameter maps, each type B event comprised a succession of contractions which had similar propagation speeds, frequency and direction to fast phasic contractions. Type C events were comprised of a succession of higher amplitude contractions with no appreciable propagation. Perfusion of saline via the colon resulted in fluid entering both caeca and the onset of aborad contractions in their proximal canals. Saline was also seen to flow between caeca during contractile events however no saline was seen to enter the small intestine as has been postulated by other workers.

Blackhead disease (histomoniasis) in poultry: a critical review

After its discovery in 1893 in Rhode Island, blackhead disease was reported across the continent and soon in many other countries. It decimated the turkey industry in New England and followed production like a faithful shadow. Blackhead disease causes high mortality in turkeys, sometimes approaching 100% of a flock. In chickens, the mortality may be 10%-20% with high morbidity, although many outbreaks pass unnoticed. Early workers identified Histomonas meleagridis, a protozoan related to Entamoeba histolytica, Giardia lamblia, and Trichomonas, as the causative agent. Like many other parasites, its life cycle is complex, involving as an intermediate host, the common cecal worm Heterakis gallinarum. The necessity for bacteria for Histomonas to become virulent in the turkey and chicken, notably Escherichia coli, Bacillus subtilis, and Clostridium spp., was discovered by research in gnotobiotic birds. Changes in management brought the disease under control, although it remained the first cause of mortality in turkeys until modern antihistomonal products were developed after WWII. The ban of nitroimidazole products in the United States and Europe was followed by an upsurge in reported cases in turkeys and chickens. Immunization is not an option for prevention, as birds do not reliably become resistant to reinfection after suffering a primary exposure. Recent research demonstrated that histomoniasis could spread rapidly through a flock of turkeys by direct contact, probably involving the phenomenon of cloacal drinking. Direct transmission was not demonstrated for chickens, stressing dependence on H. gallinarum as the source of infection. The lack of suitable treatment drugs or vaccines emphasizes the importance of prevention by worm control and management.

Blackhead Disease in Turkeys: Direct Transmission of Histomonas meleagridis from Bird to Bird in a Laboratory Model

The spread of Histomonas meleagridis infections through groups of turkeys in the absence of the cecal worm vector (Heterakis gallinarum) was studied in a battery cage model. Battery-reared poults were exposed at 2 wk of age by commingling with infected birds into cages that had the floor lined with paper. One treatment received no exposure, whereas other birds were commingled with two, three, or four birds/cage (25%, 37.5%, or 50%) inoculated per cloaca with cultured H. meleagridis (200,000/bird). Inoculated birds died at 7-13 days postinoculation (DPI) showing typical liver and cecal lesions of histomoniasis. By 14 DPI, 87.5% of the directly inoculated birds died or had severe lesions of histomoniasis. Turkeys commingled with two, three, or four infected birds became infected at the rate of 72%, 80%, or 75%, respectively. In another experiment, two birds/cage (25%) were inoculated with Histomonas from culture and allowed to commingle with other birds for 1, 2, 3, or 4 days. Two of 12 (16.7%) birds had minor cecal lesions after contact with inoculated birds for 1 day, but 87.5%-100% became infected if inoculated birds remained in the cage for 2-4 days. Contemporaneous inoculation with cecal coccidia (Eimeria adenoeides) as a predisposing factor in blackhead infections was studied using the model. Turkey poults directly inoculated with Histomonas were allowed to commingle for 5 days with uninoculated birds that had received inoculation with 0, 10(3), or 10(4) sporulated oocysts. The coccidian infection appeared to interfere with transmission of blackhead infection by 7 DPI, as suggested by lessened severity of cecal lesions and a lower percentage of infected birds. These studies confirm that histomoniasis is transmitted readily from directly exposed young turkeys to others in the absence of the cecal worm vector, and that this phenomenon can be reproduced in battery cages as an experimental model.

Infection of turkeys with Histomonas meleagridis by the cloacal drop method

The infection of turkeys with Histomonas meleagridis was attempted in the absence of its normal vector Heterakis gallinarum, using several experimental techniques. Battery-reared poults were inoculated at 2 wk of age with histomonads cultured in vitro, by several routes, including (a) per os (PO), (b) intradoacal (CI), and (c) cloacal drop (CD). Feed restriction was also studied as a predisposing factor. Intracloacal inoculation (CI) consistently produced severe infections in all experiments. In several experiments, turkeys did not become infected after inoculation PO with 1 x 10(5) cultured histomonads. Feed restriction prior to inoculation did not make turkeys susceptible to infection inoculated PO. However, when liquid cultures containing histomonads were applied to the vent (CD) and the dorsal lip stimulated to initiate cloacal drinking, the histomonads were taken into the cloaca and transported to the ceca by retrograde peristalsis. Heavy infections were produced by this method, with severe liver and cecal lesions recorded when birds were necropsied 12 days later. These results suggest that CD may provide ready entry into the lower intestinal tract for these parasites and may facilitate spread of infection through flocks.

Location of the ureteral openings in the cloacas of tinamous, some ratite birds, and crocodilians: a primitive character

Cloacas of 67 avian species, of both sexes, from various habitats and differing dietary habits, were examined macro- and microscopically to investigate possible variation in the location of the ureteral openings. Differing from most birds studied, in adult male Rhea americana and several tinamous species the ureters were found to open into the coprodeum. In these species the urodeum receives only the vas deferens or oviduct. Similarly, in crocodiles Caiman crocodilus yacare, but not in lizards Tropidurus montanus and snakes Crotalus durissus terrificus, the ureters empty into the coprodeum. This similarity between ancient birds (ratites and tinamous) and crocodiles may indicate a primitive character linking reptiles and birds. This unusual position of the ureteral orifice can represent an adaptation to facilitate urine collection into the coprodeum and large intestine. Another possibility is that this variation in ureter position is a male reproductive strategy to avoid the mixture of urine and semen in the cloaca. There were no evident correlations between the location of the ureteral openings and the birds' habitat, diet, or histology of the coprodeal mucosa. The occurrence of a phallus in eight species of birds was detected, as well as a peculiar vascularization related to the coprodeal epithelium of anseriformes. Together, these data add to the scarce information about the morphophysiology of the avian cloaca, and also contribute to clarify avian phylogenetic linkages.

Quantification of digesta flow into the caeca

1. A caecal intubation technique was developed to determine the amount of digesta that enters the caeca of fed and feed-deprived chickens. 2. Dry matter intakes per day for control and caecostomised chickens were not significantly different. 3. For fed and feed-deprived roosters, water intake was significantly increased by caecostomy in control birds and was significantly increased by feeding. 4. Amount of caecal dry matter excretion was significantly increased by feeding, but no difference in caecal water excretion was observed. 5. The ratio of caecal excretion (caecal/total excretion) of dry matter and water tended to decrease in response to feeding. 6. It is concluded that dry matter entry into the caeca represents 18% or 25% of the total dry matter excretion in fed or feed-deprived birds, respectively. Corresponding values for water entry are 17 and 26%. Therefore, the caeca play an important role in water balance.

Effects of caecal ligation and colostomy on water intake and excretion in chickens

1. The effect of caecal ligation and colostomy on water intake and excretion were examined in chickens fed a low-protein diet or a low-protein diet supplemented with urea. 2. When fed a low-protein diet, the water intake and the ratio of water intake to food intake were increased by colostomy (P < 0.05) but not changed further by caecal ligation of colostomised chickens. 3. When fed a low-protein diet supplemented with urea, the amount of water intake and the ratio of water intake to food intake were not changed by either treatment. 4. Total water excretion was much higher in the colostomised plus caeca-ligated chickens than in other 3 groups fed both types of diet (P < 0.05). 5. The amount of faecal water excretion was increased by cecal ligation in colostomised chickens fed either diet (P < 0.01). 6. No effect of any treatment on water balance was observed in chickens fed either diet. 7. It is concluded that the lower intestine plays a useful role in the water economy of chickens fed a low-protein diet or a low-protein diet supplemented with urea.

Effect of caecectomy on growth, moisture in excreta, gastrointestinal passage time and uric acid excretion in growing chicks

1. The effect of caecectomy on nitrogen utilisation and excretion was examined in growing chicks fed on a commercial diet. 2. Caecectomy had no significant effect on food intake or body weight gain. 3. Caecectomy caused significantly higher moisture content in excreta (P<0.01). 4. Gastrointestinal passage time of digesta was significantly shorter in caecectomised chicks than in control chicks (P<0.05). 5. Caecectomy tended to improve nitrogen utilisation rate in growing chicks. 6. The treatment significantly decreased uric acid excretion (P<0.01) and excretory uric acid-N/total nitrogen excretion (P<0.01). 7. It is concluded that the effects of caecectomy on nitrogen metabolism in growing chicks are similar to those in adult chickens.

Significant role of the nitrogen recycling system through the ceca occurs in protein-depleted chickens

This study focuses on the role of the ceca in nitrogen nutrition in chickens (Gallus domesticus). Urea is a very good nitrogen tracer for these studies. Little urea is synthesized by chickens due to the absence of carbamyl phosphate synthetase, an essential enzyme initiating the urea cycle. Urea is utilized by chickens when crystalline amino acid diets low in nonessential nitrogen or diets containing low concentrations of intact protein are fed, and most ureolytic activity is found in the ceca. Dietary urea was absorbed intact from the upper intestine of the chicken. The absorbed urea was excreted into ureteral urine that refluxed from the cloaca into the colon and ceca where urea was degraded to ammonia. Presumably the ammonia was incorporated into amino acids by cecal microorganisms and some urea, amino acids and proteins were absorbed from the ceca. These were utilized by the chickens. A beneficial role of ceca in the nitrogen metabolism in the chicken is, therefore, conservation of urinary nitrogen in protein-depleted chickens.

Ligation of caeca improves nitrogen utilisation and decreases urinary uric acid excretion in chickens fed on a low protein diet plus urea

1. The effect of the ligation of the caeca on nitrogen utilisation and nitrogen excretion was examined in conventional chickens fed a diet containing 50 g protein/kg plus urea. 2. Ligation of the caeca significantly improved nitrogen balance and utilisation by up to more than 2 times as much as those of controls (P < 0.05). 3. The treatment significantly decreased uric acid excretion by 77 mg nitrogen/day (P < 0.01) and also total nitrogen excretion (P < 0.05): the former decrease almost explained the latter. 4. No effect of the ligation of caeca on urea and ammonia excretion was observed. 5. It is concluded that nitrogen metabolism in chickens is affected by possible changes in caecal fermentation by preventing entry into the caeca of substances from urine and digesta.

Myoelectric activity of the cecum in fed and fasted domestic fowl (Gallus sp.)

To study cecal motility and its relation to the fed and fasted condition in domestic fowl, we sutured 7 miniature electrodes onto the ceca and ileum of 4 roosters. After recovery from the surgery, the birds received recordings of myoelectric activity for a total of 169 h while fasted and for 28 h while in the fed state. We found that single or brief clusters of action potentials (APs) occurred in the cecal smooth muscle at mean frequencies of 10.8 to 25.0/h, with the fewest when the lumen contained little food (after fasting > 24 h). Virtually all APs propagated, whether orad (toward the ileocecocolic junction) or retrograde (toward the cecal tip), with retrograde activity significantly more frequent (P < 0.001). Propagation velocity was rapid, varying from 8 to 750 cm/min (mean = 106 cm/min), being slower when birds were in the fed state. Thus, fasting resulted in fewer and more rapid APs and more that propagated toward the cecal tip. Motor activity was well coordinated between ceca, both organs showing essentially simultaneous spike activity; 72% of APs occurred within 8.1 s of each other. No relationship between ileal and cecal activity was apparent. Prominent slow waves were recorded in the ceca (5 to 5.5/min), the same slow-wave frequency as in the ileum (small intestine). From the results obtained here and from earlier studies, we conclude that the single or brief clusters of APs represent contractions that produce mixing of the luminal contents; occasional periods of protracted APs represent evacuation of cecal contents.

Effect of colostomy on the occurrence of dietary [15N]urea in intestinal contents, blood, urine and tissues in chickens fed a low protein diet plus urea

1. The occurrence of 15N was examined in excreta for 10 h, and in intestinal contents, blood and tissues at 10 h after [15N]urea was fed to conventional and colostomised cockerels. 2. Total-15N excretion and 15N-balance in control chickens were 18.88 and 44.79 mg/kg body weight/10 h), respectively. The former was increased and the latter was decreased by colostomy by 10.75 mg (P < 0.01). 3. Amounts of [15N]urea, [15N]ammonia and [15N]uric acid excreted by control birds were 13.78, 3.90 and 0.18 mg/kg body weight/10 h or 0.73, 0.21 and 0.01 of the total-15N excreted respectively. 4. The [15N]urea, [15N]uric acid and total-15N excreted were all increased after colostomy but [15N]ammonia was decreased (uric acid P < 0.05, others P < 0.01). The increase in total-15N was mostly accounted for by [15N]urea. 5. Colostomy resulted in significantly less total-15N in the contents of the whole intestine (P < 0.01), less total-15N, [15N]ammonia and [15N]urea in the contents of the colo-rectum (P < 0.01) and less total-15N and [15N]urea in the contents of the upper intestine (P < 0.05); it did not affect any in caecal contents. 6. [15N]Urea in blood, liver and kidney (blood P < 0.01, others P < 0.05), and [15N]glutamine amide (P < 0.05) and [15N]uric acid (P < 0.01) in blood were significantly decreased after colostomy. 7. The results support the hypothesis that most of the dietary urea is utilised as the result of a back-flow of ureteral urea into the caeca where it is rapidly converted into ammonia which is then metabolised to other compounds.

Role of caeca in the nitrogen nutrition of the chicken fed on a moderate protein diet or a low protein diet plus urea

1. A study was carried out to investigate whether the back-flow of urine into the caeca benefits the nitrogen economy of adult cockerels fed on a diet containing 100 g protein/kg and when dietary urea is absorbed, excreted into urine and utilised. 2. No significant effects of colostomy on nitrogen utilisation were observed in chickens fed on 100 g/kg protein diet, whereas colostomy was highly effective in decreasing it in chickens on a diet containing 50 g protein/kg plus urea (P < 0.05). 3. Nitrogen utilisation in conventional birds was significantly less when a diet of moderate protein content was fed than when a low protein diet plus urea was fed, but the opposite effect was seen with colostomised birds (P < 0.05). 4. Colostomy increased urea excretion (nitrogen/kg body weight/day) from 4 to 9 mg in chickens fed on the moderate protein diet, but greatly, from 45 to 182 mg, in those fed on the low protein diet plus urea (P < 0.05). 5. Blood urea concentration increased by about 20 mg per 100 ml in 3 h, a value which was maintained up to 6 h but which returned to the prefeeding concentration at 24 h; both control and colostomised chickens on the low protein diet plus urea responded similarly. 6. After feeding urea, half the daily excretion of urea was observed to occur within 6 and 9 h, respectively, in control and colostomised chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Cecocolonic motility in the chicken. Effects of cholecystokinin

The aims of this work were 1) to define electromyographically the motility pattern of chicken ceca and colon; 2) to study the changes induced by photoperiod and food intake on the motility of this area and 3) to characterize the motor effects of intravenous (i.v.) cholecystokinin in vivo, measuring changes in electrical activity and intracecal pressure. Electromyographical studies show that in ceca, the spike burst frequency is higher during the day than during the night and in the fed than in the fasted state; about 90% of the bursts propagate towards the apex and corresponde to filling movements. In the colon the spike burst frequency during the day is 2.9 bursts/min in animals fed ad libitum. Nocturnal recordings in animals fed ad libitum and diurnal recordings in fasted animals show a significantly decreased electrical activity. Both CCK-8s and CCK-4 induce a dose-dependent decrease of colonic electrical activity and a dose-dependent increase in the number of colonic defecations. CCK-4 also causes a slight inhibition in the cecum, whereas CCK-8s induces an increase in cecal electrical activity. Intracecal pressure recordings performed in anaesthetized animals provide similar results. In conclusion, the cecocolonic motility of the chicken displays a circadian pattern and undergoes substantial modifications in the fed compared to the fasted state. CCK-8s is not mediating the increased colonic activity that follows food intake, as its effects on colonic motility are inhibitory. In contrast, i.v. CCK-8s induces defecation and a dose dependent increase in cecal electrical activity, intraluminal pressure and colonic defecation. Intravenous CCK-4 induces inhibitory effects both on ceca and colon.

Occurrence of intraportally-infused urea-15N in the urine of domestic fowl

1. Measurements were made in situ to determine the occurrence of intraportally infused urea-15N in ureteral urine of the fowl. 2. Of the total amount of infused urea-15N, 15% was excreted intact into the urine (90% of urinary total 15N) whereas 9% remained unchanged in the blood (78% of blood non-protein-15N). 3. The proportions of non-protein-15N in the blood, liver and kidney were 12, 3 and 1%, respectively of the infused 15N. Protein-15N was 3% of that infused in blood and much less in liver and kidney. 4. About 1% of the infused 15N was observed in the urinary uric acid, and 3% of the infused 15N in non-protein N, other than urea, ammonia and glutamine amide N, of blood and liver. 5. No appreciable amounts of 15N were present in ammonia and glutamine amide N of blood, liver or kidney and in uric acid of liver or kidney. 6. The caecal contents contained about 1% of the infused 15N with 15% of this as ammonia-15N. 7. It is concluded that intraportal urea is mostly excreted unchanged into ureteral urine of the fowl.

Effect of colostomy on the utilisation of dietary nitrogen in the fowl fed on a low protein diet

1. The effect of the inhibition of urine back-flow into the colon and caeca by colostomy on the utilisation of dietary nitrogen by fowls fed on a low protein diet and receiving free or restricted water supply was investigated. 2. Colostomy caused an increase in water excretion and a resultant increase in water intake to maintain water balance. 3. Colostomy tended to decrease nitrogen balance and nitrogen utilisation (N balance/N intake) to negative values, and these decreases became significant when water was restricted (P less than 0.05). 4. Excretory uric acid, ammonia, urea and total nitrogen were significantly increased after colostomy in water-restricted fowls (P less than 0.05), but such significant effects were not observed, except for ammonia, in fowls given water ad libitum. 5. It is concluded that the back-flow of urine into the caeca plays a significantly useful role in the utilisation of nitrogen in the fowl fed on a low protein diet especially when water intake is restricted.

Absorption and metabolism of purines by the lower intestine of the chicken

1. Absorption of purines and their metabolism by the lower intestine were estimated by using the everted gut sacs from the colo-rectum and caecum of the chicken. 2. Adenine, hypoxanthine and uric acid were appreciably absorbed from the colo-rectum and caecum, and an especially high rate was observed in the absorption of uric acid from the colo-rectum. 3. Guanine was not absorbed unchanged from either the colo-rectum or the caecum and a small amount of xanthine was absorbed only from the caecum. 4. Hypoxanthine was also absorbed in uric acid form, to a much lesser extent, in xanthine form from the colo-rectum and caecum, adenine and xanthine in uric acid form from the colo-rectum and adenine in hypoxanthine form from the colo-rectum and caecum. 5. Adenine was metabolized to hypoxanthine and xanthine, guanine and hypoxanthine to uric acid and xanthine, and xanthine to adenine, in both mucosal fluids of the colo-rectum and caecum. The conversion of guanine to uric acid in the caecum was most active, being almost twice as much as that in the colo-rectum.

Chemical composition of caecal contents in the fowl in relation to dietary fibre level and time of day

1. Immature hens were preconditioned to a standard diet containing either 0, 100, 200 or 400 g/kg of added dried grass, 200 g/kg powdered cellulose, or 200 g/kg grass with an enzyme supplement, and were killed at either 10.30, 12.30 or 15.30 hr (after measurement of intestinal sugar absorption reported elsewhere). 2. Contents of caeca removed from these birds immediately after death were weighed and analysed for pH, uric acid, free sugars and volatile fatty acids, and the results related to dietary fibre level and time of day (of death). 3. Wet weights and uric acid concentrations of caecal contents both increased with increasing grass in the diet; neither measure varied with time, thus supporting the proposal that filling of caeca is continuous. Values of pH were all close to neutrality. 4. Mean molar concentrations of glucose, galactose, mannose, xylose, arabinose, fucose and rhamnose were in the proportions 36:2:3:1:4:1:1, respectively. Xylose and rhamnose declined with increasing grass; as did glucose, galactose and mannose with added cellulose; glucose, mannose and arabinose levels changed with time. The relative abundance of glucose in caecal contents should be taken into account when estimating contributions of fermentation products to energy balance. 5. Mean concentrations of acetate, propionate, butyrate, iso-butyrate, valerate and iso-valerate were in the proportions 72:22:16:1:2:2. Acetate declined and iso-valerate increased with increasing grass; the cellulose and enzyme treatments caused increases in acetate and valerate respectively; butyrate, iso-butyrate and iso-valerate levels changed with time.

Morphometry of the galliform cecum: a comparison between Gambel's quail and the domestic fowl

Tissues from the proximal, middle, and distal regions of the ceca of Gambel's quail and domestic fowl were examined by scanning and transmission electron microscopy. Cellular and subcellular structures, including epithelial cell height, mitochondrial volume fraction, microvillous surface area, proportion of goblet cells, and junctional complex characteristics, were quantified by a variety of stereologic procedures and other measurement techniques. The mucosal surface of quail cecum shows a much more highly developed pattern of villous ridges and flat areas than that of fowl cecum. The fowl has significantly greater cell heights than the quail in all cecal regions. The mitochondrial volume fraction does not differ significantly with species or region, but mitochondria are concentrated on the apical side of the nucleus. In both species, the proximal cecal region has the greatest microvillous surface area. All 3 components of junctional complexes, including zonula occludens, zonula adhaerens, and macula adhaerens, are quantified. When all factors are considered, the quail cecum appears to have morphological characteristics consistent with a greater potential capacity for absorption than the fowl cecum.

Physiological evaluation of diuresis in commercial broiler breeders

A physiological investigation on an outbreak of diuresis syndrome in commercial broiler breeder hens was carried out. Daily water consumption increased 4-fold and daily manure wet weight increased two-fold in affected hens. 2. The syndrome did not have a genetic basis. It was associated with kidney dysfunction which, once acquired, was not alleviated by changing the diet, the drinking water, or the environment. Diuresis ceased when water intake was restricted and returned when water was again made freely available. 3. The syndrome was not caused by nephrogenic diabetes insipidus or diabetes mellitus. Key changes in kidney function associated with diuresis included: increased urine flow, decreased urine osmolality, reduced glomerular filtration rates, increased fraction of the glomerular filtration rate excreted as urine and decreased urinary hydrogen ion concentrations. 4. Preliminary histopathological findings and the physiological patterns of kidney dysfunction indicated that the diuresis syndrome was associated with permanent kidney damage, probably caused by the Arkansas strain of infectious bronchitis virus.

Microbes of the avian cecum: types present and substrates utilized

This paper discusses the types and properties of microorganisms found in avian ceca, with special reference to the chicken. Microbial activity in the cecum is primarily fermentative, but there has been little evidence of cellulose fermentation, and the predominant bacterial types are relatively inactive against other high-molecular-weight compounds of dietary origin. In all avian species examined, the consistent presence of large populations of uric acid-degrading bacteria supports the view that microbial populations in the ceca permit reabsorption of water and possibly nonprotein nitrogen from the backflow of urine. These capabilities may be of particular importance to wild birds under conditions of water and food deprivation.

Ultrastructural differences between the two major components of chicken ceca

The central parts of basis and corpus ceci from White Plymouth Rock hens on different salt regimen were investigated by light, scanning electron, and transmission electron microscopy. The mucosal surface varies from long broad, flat villi in basis to blunt rugae in corpus ceci. In the epithelium of basis ceci there are many goblet cells, whereas in corpus ceci they are few in number and predominantly located in the crypts and sides of rugae. The microvilli of basis ceci are longer than those of corpus ceci. The epithelium from corpus ceci contains apically located cytoplasmic inclusions of microtubular-like aggregations. The size and amount of these inclusions decrease towards the crypt openings, and none were observed in crypt epithelium. The mitochondria in the epithelium from basis ceci are seen close to the apical plasma membrane, but in corpus ceci they first appear deeper in the cytoplasm below the apical vesicles, microtubular-like aggregations, and lysosomes. The size and content of the apical vesicles varies between the two compartments, as do deposits of lipoglycoproteins in the intercellular space and vesicles of the lateral plasma membrane. Several differences were thus revealed between the epithelia from basis and corpus ceci, giving morphological evidence for different functions between the two compartments. There were no effects of the two salt diets on the development of microvilli, whereas some cytological differences, such as the degree of microtubular-like aggregations, were seen in corpus ceci.

Sodium and potassium concentrations in the intestinal fluids of the fowl, Gallus domesticus

1. Na and K concentrations in the luminal fluids on the jejunum, ileum and colon were measured in domestic fowl on diets containing different amounts of Na and K. 2. Physiological adjustments of the Na and K content of these fluids were observed to occur in all three intestinal segments. 3. Regulation of gastrointestinal losses of Na and K appears to be initiated in the anterior regions of the intestines of the domestic fowl and is maintained or amplified as the ingesta moves posteriorly.

Relationship of cecal and colonic motility to diet, habitat, and cecal anatomy in several avian species

Previous studies have described several types of contactile activity in the ceca and colon of turkeys. Cecal contractions were termed major and minor; major were propulsive, and minor were presumed to be mixing contractions. Both types propagated either orad or aborad. Colonic contractions were termed long-duration and short-duration, with both types being propulsive. Long-duration contractions were directed aborad; short-duration were directed orad, i.e., antiperistaltic. The latter are believed to be responsible for filling of the ceca from colonic contents and for urinary reflux through the colon. Of eight wild species examined radiographically, there appeared to be little relationship between the cecal size, the nature of colonic antiperistalsis, the type of diet, or the availability of water in the habitat for each species.

Uric acid decomposition in the lower gastrointestinal tract

Uric acid is the end product of nitrogen metabolism in birds. Despite the very low aqueous solubility of this purine compound, few crystals of uric acid are found in the urine. Instead, uric acid is packaged into small spheres that can pass easily through the duct system of the kidney. After entering the cloaca, these spheres are moved with the urine by antiperistalsis into the rectum and digestive ceca. In the ceca, the uric acid is exposed to a large population of bacteria that can use the uric acid as a metabolic substrate. These bacteria degrade the uric acid to volatile fatty acids (VFA) and ammonia. The VFA are absorbed by the cecal tissue, and the ammonia is incorporated into the production of glutamine. The refluxing of uric acid into the ceca and its subsequent degradation by bacteria provides an effective mechanism for the reclamation of carbon and nitrogen from the urine.

Ammonia production from uric acid, urea, and amino acids and its absorption from the ceca of the cockerel

Experiments were conducted in situ and in vitro in the ceca to measure ammonia production from uric acid, urea, and amino acids and its absorption. When uric acid was injected into a cecal sac containing mixed cecal microfloras, 77% disappeared within 1 hour, with a concomitant increase in ammonia concentration. When [15N]uric acid was added to the ceca in situ, 28% was converted to ammonia after 30 minutes. About 92% of the ammonia introduced into a cecal sac disappeared from the lumen fluid within 30 minutes. About 43% of each of urea nitrogen and glutamine-amide nitrogen was converted to ammonia-nitrogen, and 25% of uric acid-nitrogen and epsilon nitrogen of the arginine was found in ammonia. The conversion of aminonitrogen of glutamic acid and glycine to ammonia amounted to 19-20%, whereas that of alpha-alanine totaled 11%. It is concluded that dietary and urinary nitrogenous compounds that find their way into the ceca are useful nitrogen sources for ammonia production by microflora in the ceca of the chicken, and that ammonia is absorbed rapidly from the ceca.

Ammonia production from uric acid and its absorption from the caecum of the cockerel

1. Experiments were done in vitro and in situ in the caeca to measure ammonia production from uric acid and its absorption. 2. When uric acid was introduced into a caecal sac containing mixed caecal micro-organisms 0.77 disappeared in 1 h, with the concomitant appearance of ammonia. 3. Amounts of ammonia produced from added [15N] uric acid in the caeca in situ after 30 min and in caecal medium in vitro after 10 h, were 0.28 and 0.25 respectively of the added 15N. 4. About 0.92 of the ammonia introduced into a caecal sac disappeared from the lumen fluid in 30 min. 5. It is concluded that ammonia is produced from uric acid by caecal micro-organisms and rapidly absorbed.

Ammonia production from amino acids and urea in the caecal contents of the chicken

1. Ammonia production from urea and amino acids in the caecal contents of the chicken was evaluated using 15N-labeled nitrogenous compounds. 2. About 43% of each of urea nitrogen and glutamine amide nitrogen was converted to ammonia nitrogen, but only 25% of epsilon-nitrogen of the added arginine, a precursor of urea, was found in ammonia. 3. Amino nitrogen of the separately added glutamic acid and glycine to be converted to ammonia was 19-20% of their added amounts, whereas that of alpha-alanine was 11%. 4. It is concluded that dietary and urinary amino acids and urea which find their ways into the caeca are useful nitrogen sources for ammonia production by microflora in the caeca of the chicken.

The retention and metabolism of N tau-methylhistidine by cockerels: implications for the measurement of muscle protein breakdown determined from the excretion of N tau-methylhistidine in excreta

Excreta were collected for four consecutive days from 4- to 18-week-old cockerels following subcutaneous injection of N tau-[14CH3]methylhistidine. The recoveries of radioactivity in excreta were incomplete and progressively decreased with increasing age. Most of the radioactivity not recovered in excreta after 4 d was found in skeletal muscle where greater than 55% of the radioactivity present was in the N tau-methylhistidine-containing dipeptide, balenine. This peptide appeared to be relatively stable so that most of the labelled N tau-methylhistidine incorporated was not released during the period of the recovery measurements. The total pool of non-protein bound N tau-methylhistidine (free (free N tau-methylhistidine + balenine) in pectoral and mixed thigh muscles increased with age and relative to the daily excretion of N tau-methylhistidine. At 18 weeks the pool was 3.3 times the daily excretion of N tau-methylhistidine. These observations account for the decreasing recoveries of radioactivity in excreta described previously, due to progressive dilution of labelled N tau-methylhistidine in an expanding pool of non-protein-bound N tau-methylhistidine, part of which was relatively stable. It is concluded that excretion of N tau-methylhistidine by 4- to 18-week-old cockerels cannot be used as a reliable index of muscle protein breakdown in vivo.

Active pyrimidine absorption by chicken colon

Pyrimidine absorption by chicken large intestine was investigated employing the everted sac and flux chamber techniques. 3H-labelled uracil was used as substrate. The small intestine and the colon unlike the caecum, transported uracil from the mucosal to the serosal surface against a concentration gradient in the everted sac experiments. Furthermore, there was a net transport of uracil from the mucosal to the serosal side of the colon and jejunum in the flux chamber experiments. Uracil transport by the everted colon sacs against a concentration gradient was inhibited when the purine hypoxanthine was present in the incubation medium. Uracil transport by the everted colon sacs was also inhibited under anaerobic conditions and when 2,4-dinitrophenol was present in the incubation medium. Replacing the Na+ ions of the incubation medium by Li+ ions also caused an inhibition of uracil transport. It is concluded from these results that uracil (and probably other pyrimidines) are absorbed from the chicken colon by a Na+ ion-dependent active transport process having also an affinity for purines.

Cecae of desert quail: importance in modifying the urine

The importance of the digestive ceca in the modification of ureteral urine was evaluated in conscious, unrestrained desert quail. Cecaectomized (Cx) birds took in slightly more food and water and excreted more solids and water than did sham operated controls. The percent utilization of food for the Cx birds was 76 and 79% for the sham operated controls. Urate output was 47 ml/kg day for Cx and 41 ml/kg day for the sham operated controls. Water content of the excrement was 90% for the Cx and 85% for the sham operated controls. There was a slight but insignificant increase in uric acid excretion in the droppings of cecaectomized birds.

Gastrointestinal motility and its regulation

Cineradiography and intraluminal pressure recordings, together with data from strain gauges and Ag/AgCl electrodes, have been used to evaluate gastrointestinal motility in fowl. Substantial differences exist with mammals. Gizzard and duodenal activities are closely in phase with one another, and intrinsic slow wave control is lacking although duodenal slow waves may be recorded. These slow waves may be more important in ileum, colon, and ceca. Extensive reverse peristalsis is apparent in both areas and considered normal for overall intestinal operation.