Reflux of digesta and its implications for nutrient digestion and bird health

Reflux is the anti-peristaltic induced, retrograde movement of digesta in the gastrointestinal tract (GIT). Previous research has characterized the occurrence and frequency of reflux, as well as the possible effects it has on the well-being of the chicken. Reflux may be both beneficial or harmful depending on the general health of the bird. In a healthy bird, it may present the opportunity for prolonged exposure of digesta to the enzymatic and mechanical systems of the GIT, thus leading to an increase in digestion and absorption time in the upper intestine. On the other hand, pushing caecal contents up into the intestine may increase the chance of undesirable organisms colonising the intestine, possibly resulting in subclinical infections. Another important implication of digesta reflux in chickens may relate to the use of the marker technique for determination of ileal digestibility of nutrients since the technique assumes constant, one-way flow of digesta throughout the GIT. This paper presents a brief review on the digesta reflux phenomenon and speculates how reflux could affect the general health of the chicken and how it may be manipulated by diet

Nutrient utilization and functionality of the anterior digestive tract caused by intermittent feeding and inclusion of whole wheat in diets for broiler chickens

Two experiments were carried out to study the effect of intermittent feeding, diet structure, and their interaction on the performance, feeding pattern, and digestive adaptation of broiler chickens. In experiment 1, 40 Cobb broiler chickens were fed, either ad libitum or intermittently, a commercial starter diet diluted with 150 g/kg of ground or whole wheat in a 2 × 2 factorial arrangement. Ad libitum feeding consisted of continuous access to feed in a room with 18 h of light and 6 h of complete darkness, whereas birds on intermittent feeding had restricted access to feed from 7 d of age, with 4 one-hour feeding bouts/d and one 2-h feeding bout/d from d 14. No interaction was found between feed structure and feeding regimen for any of the measurements. Although BW gain was not significantly different among any of the treatments, birds given whole wheat or fed intermittently had significantly better feed efficiency than those given ground wheat and fed ad libitum. Inclusion of whole wheat instead of ground wheat also markedly increased (

The effect of digesta viscosity on transit times and gut motility in broiler chickens

The hypothesis that an increase in luminal viscosity would result in reductions in performance parameters, digesta passage rate and frequency of reverse peristalsis was tested. Chickens were fed diets containing varying quantities of guar gum, alginic acid or corn starch to influence digesta viscosity. The two guar gum treatments yielded the highest intestinal viscosities mirrored by very high feed conversion ratios, low starch digestibility and, for birds exposed to the highest level of guar gum, very low weight gain compared to the control birds. An association between a rise in ileal viscosity and low transit times was recorded; however at the highest viscosity, transit rates were significantly less than the control. Cloacally administered Cr-EDTA was retrieved from the gizzards of birds in all treatments. The marker was recovered in greater amounts in birds exhibiting lower ileal viscosities, with the exception of birds from the high level guar gum group, displaying faster passage rates and lower ileal viscosities

Occurrence of reverse pertistalsis in broiler chickens

Two experiments were conducted to evaluate the occurrence and possible effects of certain dietary ingredients on reverse peristalsis or reflux in broiler chickens. The first experiment was a preliminary study into the occurrence of reflux while the second experiment investigated the passage of a bacterial marker and Cr-EDTA in birds fed diets of varying viscosities. The results suggest that reflux occurs throughout the digestive tract of both fasted and fed chickens. Reflux appears to be part of normal gut motility and a possible adaptive response to an absence of food, indicating that it serves to extend the digestive process. Dietary ingredients are likely to affect reflux , especially ingredients that increase digesta viscosity in the lumen. In addition, microbial populations may be relocated by reverse peristaltic contractions

Occurrence of reverse peristalsis in broiler and layer chickens

Three experiments were conducted to evaluate the occurrence and possible effects of certain dietary ingredients on reverse peristalsis or reflux in broiler and layer chickens. The first experiment was a preliminary study into the occurrence of reflux while the second experiment investigated the passage of a bacterial marker and Cr-EDTA in birds fed diets of varying viscositles. The third experiment also employed the mineral and bacterial markers but was conducted on layer birds to investigate possible differences in occurrence of reflux between layer and broiler chickens. The results suggest that reflux occurs throughout the digestive tract of both fasted and fed broiler chickens and layers. Reflux appears to be part of normal gut motility and a possible adaptive response to an absence of food, indicating that it serves to extend the digestive process. In addition, microbial populations may be relocated by reverse peristalsis contractions. Although this study provided no conclusive evidence as such, it is our opinion that dietary ingredients, especially those that increase digesta viscosity, are likely to induce reflux

How feed constituents regulate gut motility, feed utilisation and growth in broiler chickens

This thesis addresses the implications of different feed ingredients on motility, in particular reverse peristalsis, and gut development and the resulting impact on performance in the broiler chicken. Four experiments were carried out with the aim of manipulating the broiler's gut motility by various feed ingredients, and feeding practices. To elucidate possible motility responses to the dietary factors, feed passage rates, and reverse peristalsis were measured using a variety of markers. The corresponding interactions with gut development and bird performance were also recorded. Each experimental chapter has been presented as an individual study, thus, this summary will only give a general overview of the key findings of the thesis. Chapter 1 briefly describes the background information to the study, leading to the formation of the major objectives and hypotheses of the present study. Chapter 2 presents a review of the relevant literature, covering general digestive physiology and motility, gut microflora, and reverse peristalsis. The final section of the literature review describes the influence feed constituents and feeding practices have over gut development and performance in the chicken

The effect of insoluble fiber and intermittent feeding on gizzard development, gut motility, performance of broiler chickens

Two experiments were conducted to test the following hypothesis: exposing broiler chickens to coarse insoluble fiber in the diet will result in enhanced gizzard function and performance, improved adaptability to an intermittent feeding program, and an increase in the occurrence of reverse peristalsis. In experiment 1, 102 Ross 308 broiler chickens were either intermittently or ad libitum fed a basal diet, the basal diet diluted with 15% coarse hulls (consisting of equal weights of hulls from oats and barley), or the basal diet diluted with 15% of the same hulls finely ground in a 2 × 3 factorial arrangement with 17 individually caged birds per treatment. Birds fed ad libitum had access to feed continuously for 18 h/d, whereas those on intermittent feeding had restricted access to feed from 7 d of age. From 18 d of age, the restrictive-feeding program consisted of four 1-h meals and one 2-h meal per day. In experiment 2, 156 broiler chickens in 12 pen cages with wood shaving-lined floors were exposed to 1 of 4 treatment groups with 3 pens/treatment: intermittent or ad libitum feeding of a basal diet and intermittent or ad libitum feeding of a coarse hull diet, as described above. At 31 and 32 d of age, birds in experiment 1 were inoculated with chromium EDTA via the cloaca. There was no interaction between diet and feeding regimen. The addition of hulls increased gizzard weight and content and lowered (