A radiographic study of urine flow in the domestic fowl

Salt and water excretion by birds: the lower intestine as an integrator of renal and intestinal excretion

1. In the fowl, the small intestine is important for net absorption of Ca2+ and K+, but not for Na+ nor water (in this and several other species). 2. Net water absorption in birds with large saccate caeca occurs in caeca greater than rectum greater than coprodeum, but net Na+ absorption (an active process motivating other absorptive functions) occurs in rectum less than caeca and coprodeum. 3. Interspecific variability and the scarcity of comparative studies militate against broad, well-founded generalisations in this subject.

On caecal synthesis and absorption of amino acids and their importance for nitrogen recycling in willow ptarmigan (Lagopus lagopus lagopus)

The willow ptarmigan has two large caeca housing dense populations of microorganisms. Urine, containing uric acid, is transported from the cloaca into the caeca when these are filled. Here the uric acid is rapidly broken down, suggesting that the caeca take part in a recycling of excretory nitrogen. In this work it is shown that ammonia produced by the uric acid decomposition is incorporated into new amino acids in a glutamic dehydrogenase catalyzed reaction. We have, however, not been able to detect any absorption of amino acids from the caeca, indicating that nitrogen recycling via the amino acid route does not occur.

Estimation of nitrogen digestibility in poultry: content and distribution of major urinary nitrogen compounds in excreta

The investigation concerned the digestibility of nitrogen and the content of uric acid, ammonia, and urea in urine and feces in White Leghorn layers. Eight colostomized hens were given a commercial cage-layer diet. Feces and urine were collected under acid conditions. Acidified urine contained more ammonia than untreated urine. For quantitative determination of ammonia, Urine collection ought to be done under acid conditions. Of urinary nitrogen uric acid represented 88%, ammonia 7%, urea 3%, and 2% unidentified. Urinary ammonia constituted 90% of ammonia in total excreta and urinary urea 86% of the urea in excreta. By means of these distribution factors and content of nitrogen compounds in total excreta, good estimates of the nitrogen digestibility were obtained. Our method appears to be applicable to chickens of other ages, sex, breeds, and environmental conditions.

Caecal decomposition of uric acid in captive and free ranging willow ptarmigan (Lagopus lagopus lagopus)

Urine entering the caeca of birds contains significant amounts of uric acid. The discovery of great numbers of bacteria utilizing uric acid in the caeca has encouraged the discussion about nitrogen recycling in birds. In this work caecal decomposition of uric acid in wild and captive willow ptarmigan has been investigated using radioactively labelled uric acid injected directly into one of the caeca. The appearance of radioactive CO2 in the expired air was taken as an indication of uric acid breakdown. The decomposition occurred at a rate corresponding to a half-life of 26 min (11-36 min). The results are in accordance with the previously reported observations of huge numbers of uric acid utilizing bacteria in the caeca of a variety of birds, and also with the nitrogen recycling theory. However, no conclusion concerning the nitrogen recycling can be drawn.

Water balance of colostomised and non-colostomised hens at different ambient temperatures

1. The quantities of water gained and lost, and hence the total water balance, were determined in normal and colostomised White Leghorn laying hens at ambient temperatures of 5, 20 and 35 degrees C. 2. In both groups the water intake and water loss at all temperatures were well balanced. 3. Water to food ratios and water content of excreta of normal hens increased with increasing temperature. 4. The water excreta at 35 degrees C are caused by an increasing urine production and not by an increased water passage through the alimentary tract.

Electrical potential changes and contractile activity of the distal cecum of turkeys

Bipolar electrodes and strain gauge transducers were implanted on the distal cecum, ileum, and colon of turkeys in order to describe 1) cecal motility, 2) relationships between cecal, ileal, and colonic motilities, 3) events occurring in these organs during cecal evacuation, and 4) cecal electric slow waves. Two types of contractions were recorded in the cecum: those with low amplitude occurring at 2.6/min (minor) and those with higher amplitude occurring at 1.2/min (major). About one-half of the time the former occurred in coordination with contractions in the colon and ileum at the same frequency but slightly out of phase. Major contractions appeared to be propagated, and aborad propagation was twice as common as orad. Accumulation of ingesta in the cecal tip was apparently prevented by contractions arising in the distal cecum and moving orad having a much greater amplitude than those moving aborad. As many as six or seven major contractions occurred during the last 2 min prior to cecal evacuation; one or two similar high amplitude contractions occurred in the ileum and colon at this time. Electric slow waves were rarely recorded in the ceca.

Cloacal immunisation of the turkey using a soluble antigen

1. Bovine serum albumin (BSA) in saline applied to the cloacal "lips" of turkeys was sucked in by quick movements (cloacal drinking). 2. BSA-stimulated antibody production was limited to lymphoid cells in the bursa of Fabricius and in the caecal tonsils. No serum antibody was detected after cloacal drinking of BSA. 3. This response is probably of significance in the local defence mechanism of the intestine.

In vitro antibiotic activity on cecal anaerobes with emphasis on uric acid-utilizing bacteria

A total of 741 individual colonies or representative colonial types were isolated on basal-hlf-uric acid (UA) agar plates containing various antibiotics and on two types of control media. All of the antibiotics utilized in this study were capable of reducing bacterial numbers and/or bacterial groups in vitro when compared to the control plates. None of the antibiotics were selective for the uric acid bacteria. The majority (96%) of the cecal isolates utilizing uric acid were gram-positive. The basal-half-uric acid agar was a nonselective growth medium and supported the growth of virtually every bacterial group reported to be present in the avian cecum. The cecal flora of the adult White Leghorn hens tested was observed to be composed of 23% G+ (gram-positive) rods, 24% G- (gram-negative) rods, 26% G+ cocci, 9% G- cocci, and 18% G+ coccal-bacilli.

Measurement of uric acid levels in chicken cecal contents

Uric acid levels in the cecal contents of White Leghorn males aged 6, 10, and 24 weeks of age were constant at approximately 2 mg/100 ml. Fecal samples obtained from these birds contained, respectively, 99, 107, and 156 mg/100 ml uric acid. The addition of growth promoting level of antibiotics or other feed additive to the ration of 10-week-old White Leghorn males had no effect upon cecal uric acid levels.

Colonic motility in domestic turkeys

This study was performed to determine (1) if electrical slow waves could be recorded from the colon of turkeys, and (2) how ingesta moves into and through the colon despite colonic antiperistalsis. Electrical activity and contractile forces were monitored via implanted bipolar electrodes and strain gage transducers (SGT), respectively. Two types of slow waves, small (sSW) and large (lSW) were recorded simultaneously. The former were correlated with antiperistaltic contractions observed radiographically and with small contractions recorded with SGT, the latter were correlated with large contractions recorded via SGT. The sSW had higher frequencies distally than proximally while the frequency gradient for the lSW was just the opposite. The sSWs were believed to be involved in regulation of antiperistalsis while the lSW were believed to be involved in regulation of the large contractions which, on the basis of the lSW frequency gradient, appeared to be peristaltic and to be primarily responsible for aborad movement of colonic digesta. The small contractions were believed to be responsible for reflux of urine from the cloaca into the colon and ceca and for cecal filling.

Endogenous uric acid and urea metabolism in the chicken

1. Four chickens were used in nine successive experiments using a single injection radioisotope dilution technique to study the kinetics of endogenous uric acid and urea metabolism. 2. Starvation lowered uric acid and urea entry rates, but elevated the extent of degradation of these compounds. 3. Urea turnover time and the extent of urea pool degradation were higher, and urea excretion rate was lower than that of uric acid. 4. In colostomised chickens, the extent of uric acid and urea degradation were lower than in non-colostomised birds. 5. The average uric acid and urea entry rates in chickens fed on a diet containing 200 g protein/kg were 7.32 and 2.6 mumol/h g liver, respectively. 6. It is concluded that the contribution of uric acid and urea to the nitrogen economy of the birds is negligible.

Studies on site finding and site specificity of Eimeria praecox, Eimeria maxima and Eimeria acervulina in chickens

Sporozoites of 3 species of Eimeria were introduced into the caecum of young chickens. E. praecox and E. maxima failed to develop in this site, but light infections of E. acervulina were detected. Infection of the small intestine with all 3 species occurred when sporozoites were introduced via the caecum. Infections were produced when mucosal scrapings of small intestine from birds, inoculated via the caecum 1-4 h previously, were inoculated orally to susceptible chickens. Experiments with 51Cr-labelled sporozoites of E. praecox introduced in the caecum, confirmed that small numbers of sporozoites are capable of migrating from the lower to the upper intestine. Sporozoites were not transferred with liver tissue from birds given sporozoites via the caecum but were transferred with the liver of chickens given sporozoites intraperitoneally.

Effects of exteriorization of the ureters on the water metabolism of the domestic fowl

1. Six domestic fowls were operated for exteriorization of the ureters.2. Three weeks after the operation their food and water intake was compared with that of six unoperated control fowls of similar weight.3. Water intake was calculated from the amount of water drunk, the metabolic water and the water content of the food eaten; while water loss was estimated from the water content of urine and faeces excreted and from evaporation.4. Fowls with exteriorized ureters drank more than the control birds. The excess of water drunk by these birds approximated the amount of water lost in the urine.

The influence of the microflora of the alimentary tract on protein digestion in the chick

1. The course of digestion of freeze-dried and heat-damaged egg albumen labelled with14C in all its constituent amino acids was compared in germ-free and conventional chicks. The albumen was given at a level of 10% in a test meal containing 28% protein. Samples of digesta were taken 5 h later and analysed for14C and nitrogenous constituents.

2. After administration of unheated albumen, 11% of the14C remained in the germ-free gut, compared with 23% in the conventional gut. The poorer digestibility of the heat-damaged albumen was shown by recovery of 42 and 47% of the14C from the gut of germ-free and conventional birds respectively.

3. With both diets there was a higher14C: nitrogen ratio in the contents of the lower gut of conventional birds. Most of the N remaining in the gut was composed of protein or the hydrolysis products of protein, the amounts of which tended to be higher in the germ-free environment; urea and uric acid formed only a small proportion of the total N. There was less urea and more uric acid in the lower gut and excreta of conventional chicks.

4. It was concluded that microbial activity did little to increase the availability of protein to the chick. However, its effect on the nitrogenous material in the lower part of the alimentary tract might result in low recovery of N in the faeces and thus lead to erroneously high estimates of protein quality in tests with conventional chicks.

Volatile fatty acids in the digestive tract of the fowl

1. Examination of the digesta from all regions of the avian digestive tract showed that volatile fatty acids (VFAs) were present in greatest concentration in the caeca and that they comprised mainly acetic, propionic and butyric acids.

2. All droppings contained VFAs but they were present in highest concentration in those of caecal origin. Caecectomy was followed by a marked reduction in the total output of VFAs.

3. Birds 14–20 weeks of age had similar concentrations of VFAs along the tract and similar numbers and distribution of micro-organisms.

4. Portal blood contained all the VFAs found in the digestive tract whilst peripheral blood contained only acetic and formic acids.

5. The almost complete absence of VFAs from the tract contents of germ-free birds showed that the VFAs normally present in the tract were of microbial origin.

6. The presence of similar levels of acetate in the peripheral blood of conventional and germfree birds indicated that circulating acetate was mainly of endogenous and not microbial origin.

7. The significance of VFAs as an energy source is discussed.