Two lines of broilers divergently selected for a high (D+) or a low (D-) AME(n) on a wheat-based diet were studied for morphological and histological characteristics of the digestive tract. A total of 630 birds of both lines were slaughtered after a 23-d feeding period. Digestive tract morphology and intestinal histology were investigated on a total of 24 birds to describe the consequences of divergent selection. Birds of the D+ line had 34% heavier gizzards (P < 0.001) and 22% heavier proventriculi than their D- counterparts. In contrast, intestines were 15 to 40% heavier in D- birds, mainly in the jejunum (P < 0.001) and ileum (P < 0.001). Intestinal segments were also longer (between 3 and 6%) in the D- birds. Intestinal villi were larger and longer in D- birds (P < 0.001), mainly in the jejunum (14 to 16%), and crypts were 10 to 15% deeper for the 3 intestinal segments in D- birds (P < 0.001). Muscle layers of the intestine were 17 to 24% thicker (P < 0.001) and goblet cells were 27 to 34% more numerous in the jejunum and ileum of D- birds (P = 0.027). This new characterization of the 2 lines shows that divergent selection based on AME(n) modified the morphology of the proventriculus and gizzard, suggesting greater activity of this compartment in D+ than in D- birds. Intestinal adaptation revealed by visceral organ weight and length and histological modifications in D- birds can be viewed as an attempt to compensate for the low functionality of the gastric area.

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The microflora of the digestive tract of poultry is still incompletely known. Microbial populations of varying size and complexity occur throughout the digestive tract and the highest and most complex floras are found in the crop and the caeca. The upper part of the digestive tract is predominantly settled by facultative anaerobes, whereas the caeca are mainly the site of obligate anaerobes. The types, numbers and metabolic activities of the organisms are affected by numerous factors such as individual, animal age, environment, and diet.Bacteria produce various metabolites that can be useful or detrimental to the host. Interactions between bacteria and the gastrointestinal epithelium lead to various structural and functional modifications of the digestive tract. Bacteria can impair lipid digestion and may modify carbohydrate and protein digestion. They cause an increase in energy and amino acid requirements. They have a negative effect on vitamin nutrition. Beneficial bacteria can protect birds against pathogens through a competitive exclusion process. Moreover, the flora is involved in the development of the intestinal immune system. Overall, bacteria have a negative effect on bird growth. They may also have an effect on meat and egg quality.Improved knowledge of the microflora of the digestive tract and its consequences may contribute to its control and beneficial use for birds as well as breeders, consumers and the environment.

-Corn-or wheat and barley-based diets were supplemented or not with xylanase and β-glucanase (Quatrazyme HP, Nutri-Tomen, France) and fed to broiler chickens (n = 12 per group) from 3 to 25 days of age. The unsupplemented wheat and barley-based diet reduced (P ≤ 0.05) weight gain and feed intake, and increased the feed conversion ratio as compared to the corn-based diet. Viscosity in the supernatant of the small intestine contents was increased (P ≤ 0.05), whereas pH and osmolality values decreased (P ≤ 0.05). Crude fat and protein digestibility were reduced as well as the apparent metabolizable energy (P ≤ 0.05). Moreover, wheat and barley consumption, when compared with the corn-based diet, produced an increase in the microflora of the caeca, with 10.0 vs. 8.9 log CFU·g -1 for facultative anaerobic bacteria, 6.5 vs. 5.6 log CFU·g -1 for E. coli and 9.7 vs. 8.3 log CFU·g -1 for Lactobacillus. The addition of xylanase and β-glucanase to the wheat and barley-based diet significantly reduced the viscosity of the small intestine contents and improved (P ≤ 0.05) weight gain, feed intake and feed conversion ratio. The digestibility of the nutrients, the apparent metabolizable energy and the osmolality of the small intestine contents were also increased without alteration in pH values. At the same time, the number of total facultative anaerobic bacteria and E. coli decreased significantly (P ≤ 0.05). In conclusion, the addition of xylanase and β-glucanase improves the digestibility of a wheat and barley-based diet, probably by reducing the viscosity of the intestine content and by impeding the growth of bacteria (total facultative anaerobic bacteria, E. coli). Abbreviations: AME, Apparent metabolizable energy; AME n , Apparent metabolizable energy to zero nitrogen balance; CFU, Colony forming units; DM, Dry matter; GE, Gross energy; HPAEC, High performance anion exchange chromatography; NSP, Non starch polysaccharides; RAV, Real applied viscosity; VFA, Volatile fatty acids.Résumé -Influence de la supplémentation du régime alimentaire par une association de xylanase et de -glucanase sur la digestibilité des nutriments, les conditions physico-chimiques dans l'intestin grêle et l'équilibre de la flore caecale chez le poulet nourri avec un aliment à base de blé et d'orge. Trente-six poulets de chair (Ross) sont, entre le 3 e et le 25 e jour d'âge, nourris soit avec un aliment témoin à base de maïs soit un aliment expérimental contenant du blé et de l'orge supplémenté ou non avec une association de xylanase et de β-glucanase (Quatrazyme HP, Nutri-Tomen, France). Le gain de poids et l'efficacité alimentaire sont plus faibles (P ≤ 0,05) chez les poulets nourris avec un régime à base de blé et d'orge que chez les témoins. La baisse des performances zootechniques est liée à une réduction de la pression osmotique, une diminution (P ≤ 0,05) de la digestibilité des lipides et des protéines et une baisse de l'énergie. En revanche, la viscosité du contenu intestinal, le nombre de bactéries anaérobies facultatives (10,0 vs....

1. The effects of whole grains of wheat on the digestive tract of broiler chickens was studied. A complete pelleted feed was compared with free choice feeding of whole wheat and a pelleted protein concentrate, given from 7 to 29 d of age. 2. Pepsin activity in proventriculus tissue was lower in whole wheat-fed birds than in complete diet-fed birds. The weight (g/kg body weight) of the gizzard was higher in whole wheat-fed birds and its contents had a lower pH. 3. In the intestine, there were no differences in deoxyribonucleic acid (DNA) concentration, protein/DNA, ribonucleic acid (RNA)/DNA, RNA/protein ratios or alkaline phosphatase activity expressed per tissue weight. The weight (g/kg body weight) of the duodenum was lower in whole wheat-fed birds and its contents had a higher pH. Also the activities of alkaline phosphatase and leucine aminopeptidase in the duodenum, and maltase in the ileum, expressed per unit of bird weight, were lower in whole wheat-fed birds. 4. These results suggest that whole grain feeding increases the chemical (pepsin in proventriculus) and physical (gizzard muscle) functionality of the upper part of the digestive tract but decreases the digestive capacity of the intestine. Higher gizzard functionality may play a positive role in the control of bacterial populations. The lower digestive enzyme activities in the intestine may be detrimental in situations of mucosal deterioration caused by intestinal disease.

The microflora of the digestive tract of poultry is still incompletely known. Microbial populations of varying size and complexity occur throughout the digestive tract and the highest and most complex floras are found in the crop and the caeca. The upper part of the digestive tract is predominantly settled by facultative anaerobes, whereas the caeca are mainly the site of obligate anaerobes. The types, numbers and metabolic activities of the organisms are affected by numerous factors such as individual, animal age, environment, and diet.Bacteria produce various metabolites that can be useful or detrimental to the host. Interactions between bacteria and the gastrointestinal epithelium lead to various structural and functional modifications of the digestive tract. Bacteria can impair lipid digestion and may modify carbohydrate and protein digestion. They cause an increase in energy and amino acid requirements. They have a negative effect on vitamin nutrition. Beneficial bacteria can protect birds against pathogens through a competitive exclusion process. Moreover, the flora is involved in the development of the intestinal immune system. Overall, bacteria have a negative effect on bird growth. They may also have an effect on meat and egg quality.Improved knowledge of the microflora of the digestive tract and its consequences may contribute to its control and beneficial use for birds as well as breeders, consumers and the environment.

1. Conventional cages are to be replaced by furnished cages or aviary systems to improve the welfare of hens. We compared the performance and egg quality of hens reared in two designs of furnished cages and of two standard cages. We also explored the consequences of the absence of beak trimming when using these designs. 2. Hens (2028) were housed from 18 to 70 weeks of age in 108 standard cages at 6 per cage (60 cmx63.5 cm), in 96 cages at 5 per cage (59.5 cmx55.5 cm) or in two designs of furnished cage at 15 per cage (24 F15M cages and 36 F15P cages made by two manufacturers) which contained equipment varying in size and location (nests, dust baths and perches). Half of the hens were beak-trimmed in each design. 3. Mortality was low in beak-trimmed hens (<5%) but was unacceptably high in non-beak-trimmed hens due to cannibalism (>40%, 516 hens). Mortality was worse in standard cages than in furnished cages. Consequently, hen-housed egg production was significantly lowered in non-beak-trimmed hens. 4. Egg laying in beak-trimmed hens reared in furnished cages occurred mainly in the nest (80 and 84.8% in F15M and F15P) but also in the dust bath (13.3 and 9.4% in F15M and F15P) and in other parts of the cage (6.7 and 5.8% in F15M and F15P). 5. The total percentage of broken (visual observation) and hair-cracked eggs (candling) was high in the furnished cage designs (15.4 and 19.6% in F15M and F15P, respectively) compared with standard cage designs (8.1 and 12.2% in S6 and S5). This was mainly due to hair-cracked eggs, the highest percentages occurring in the nests, especially in the design with a narrow nest and no egg saver (11.1% in F15M compared to 17.6% in F15P) as a consequence of egg accumulation in the cradle and relatively low frequency of manual egg collection. 6. Eggshell quality (index and breaking strength) was only slightly influenced by cage effects so differences in egg breakage were attributable to impacts related to cage design. 7. It is concluded that beak trimming remains the most effective way to prevent cannibalism, although furnished cages with a large group of hens slightly reduced the incidence, and that further development and optimisation of furnished cages is needed to reach egg quality similar to standard cages.

1. The hygienic properties of eggs produced in two designs of furnished cage were investigated and compared to two standard cage designs. 2. At 28, 37, 47 and 58 weeks of age, the proportion of dirty eggs was higher in one of the furnished cage designs while, in the other, it was similar to standard cages. 3. At 27, 33 and 60 weeks, the bacterial load on the eggshell (total aerobic bacteria and enterococci) was higher in furnished cage designs. A seasonal effect was observed with lower counts at 60 weeks (winter) than at 27 weeks (summer). 4. More dirty eggs and a higher bacterial load were observed in eggs laid outside the nests, which suggests egg hygiene in furnished cages could be similar to standard cages if the equipment in furnished cages was improved to enhance nest laying.