Irène Gabriel

Differences in the digestive tract characteristics of broiler chickens fed on complete pelleted diet or on whole wheat added to pelleted protein concentrate

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.

Microflora of the digestive tract: critical factors and consequences for poultry

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.

The effects of fructo-oligosaccharides or whole wheat on the performance and digestive tract of broiler chickens.

1. The objective of this experiment was to study two feeding methods, which could potentially act on the gut microflora, the structure and/or the function of the digestive tract and thereby improve the performance of broilers. 2. Four dietary treatments were studied: a negative control (wheat based) with no additives (C), a positive control with 0·01 g/kg avilamycin (AV), a treatment with 0·6 g/kg fructo-oligosaccharides (FOS) and a treatment with the same composition as treatment C but in which a part or all (400 g/kg) of the wheat was given as whole wheat and a concentrate supplement (WW). The measurements were: the performance from 0 to 6 weeks, the bacterial counts at 3 and 6 weeks, the digestive tract morphology and the activity of some intestinal enzymes at 3 weeks. 3. The birds given AV had better daily live weight gain (DLWG) and feed conversion ratio (FCR) compared to treatment C. The birds given FOS had a lower feed intake and a lower DLWG than the birds on treatment C but their FCR was significantly improved. WW resulted in a numerically lower feed intake and a significantly lower DLWG than treatment C. With AV, the number of aerobic mesophilic bacteria in the caeca was reduced at 3 weeks. With WW, gizzard and pancreas weights were greater and the surfaces of the ileal crypts were larger. An increased activity of leucine aminopeptidase (LAP) in the duodenum was found for treatments AV, FOS and WW. 4. In conclusion, in this study, treatments WW and FOS reduced DLWG, which may have been due to a lower feed intake during the whole period. With WW, the FCR was not affected, maybe because of both positive and negative effects on digestive tract (higher gizzard and pancreas development and LAP activity; larger crypts). However, FOS improved FCR, which may be partly explained by the higher LAP activity.

Effects of two wheat cultivars on physico-chemical properties of wheat flours and digesta from two broiler chicken lines (D+ and D-) differing in digestion capacity

1. The current experiment is the second part of a study about the effects of wheat quality on digestibility of pelleted diets for broiler chickens. In the first part, it was shown that a hard cultivar resulted in a negative effect on starch digestibility in two divergent lines of chickens (D+ and D−) selected for digestion capacity. The aim of this second part was to investigate the reasons for this negative effect of a hard cultivar (Baltimor) compared to a soft one (Scipion) in D+ and D− lines. 2. Proventriculus pepsin activity and pancreas proteolytic and amylolytic activities were estimated in 4 pools of birds: ‘D+ line (Baltimor fed)’, ‘D+ line (Scipion fed)’, ‘D− line (Baltimor fed)’ and ‘D− line (Scipion fed)’. Results suggested the greatest amount of pepsin units per g BW for D+ birds and the lowest amount of pancreas proteolytic units per g BW for D+ birds fed Scipion wheat. Pancreas showed very similar α-amylase activities among treatments. 3. In vitro hydrolyses of wheat gluten proteins with proventriculus extracts from pools of D+ and D− birds did not show any differences between hard and soft cultivars, whatever the origin of pools. 4. Pepsin hydrolysis of fine (300 to 425 µm) and coarse (1180 to 1600 µm) fractions from wheat flours (Baltimor or Scipion) showed that the 30 min proteolysis rate was highest for the fine fraction in both cultivars. No difference was observed with extended hydrolysis time. 5. In vitro digestion simulation of whole wheat flours confirmed the results previously obtained in vivo, with a negative effect of hard cultivar on starch digestion rate and no effect on protein digestion. 6. Laser particle size analyses showed that ileum digesta from birds fed with hard wheat cultivar showed the highest proportion of coarse particles. 7. Microscopic analyses of D+ ileum digesta revealed that the concentration of undigested starch granules in the subaleurone area of wheat bran particles was the highest with hard cultivar. 8. The results suggested that physical entrapment of starch granules in coarse particles was a major explanation for decreased starch digestibility values in chickens fed hard wheat diets.

Impact of Selection for Digestive Efficiency on Microbiota Composition in the Chicken.

Objectives Feed efficiency and its digestive component, digestive efficiency, are key factors in the environmental impact and economic output of poultry production. The interaction between the host and intestinal microbiota has a crucial role in the determination of the ability of the bird to digest its food and to the birds’ feed efficiency. We therefore investigated the phenotypic and genetic relationships between birds’ efficiency and the composition of the cecal microbiota in a F2 cross between broiler lines divergently selected for their high or low digestive efficiency. Methods Analyses were performed on 144 birds with extreme feed efficiency values at 3 weeks, with feed conversion values of 1.41±0.05 and 2.02±0.04 in the efficient and non-efficient groups, respectively. The total numbers of Lactobacillus, L. salivarius, L. crispatus, C. coccoides, C. leptum and E. coli per gram of cecal content were measured. Results The two groups mainly differed in larger counts of Lactobacillus, L. salivarius and E. coli in less efficient birds. The equilibrium between bacterial groups was also affected, efficient birds showing higher C. leptum, C. coccoides and L. salivarius to E. coli ratios. The heritability of the composition of microbiota was also estimated and L. crispatus, C. leptum, and C. coccoides to E. coli ratios were moderately but significantly heritable (0.16 to 0.24). The coefficient of fecal digestive use of dry matter was genetically and positively correlated with L. crispatus, C. leptum, C. coccoides (0.50 to 0.76) and negatively with E. coli (-0.66). Lipid digestibility was negatively correlated with E. coli (-0.64), and AMEn positively correlated with C. coccoides and with the C. coccoides to Lactobacillus ratio (0.48 to 0.64). We also detected 14 Quantitative Trait Loci (QTL) for microbiota on the host genome, mostly on C. leptum and Lactobacillus. The QTL for C. leptum on GGA6 was close to genome-wide significance. This region mainly includes genes involved in anti-inflammatory responses and in the motility of the gastrointestinal tract.

Heterogeneity of Persistence of Salmonella enterica Serotype Senftenberg Strains Could Explain the Emergence of this Serotype in Poultry Flocks

Salmonella enterica serotype Senftenberg (S. Senftenberg) has recently become more frequent in poultry flocks. Moreover some strains have been implicated in severe clinical cases. To explain the causes of this emergence in farm animals, 134 S. Senftenberg isolates from hatcheries, poultry farms and human clinical cases were analyzed. Persistent and non-persistent strains were identified in chicks. The non-persistent strains disappeared from ceca a few weeks post inoculation. This lack of persistence could be related to the disappearance of this serotype from poultry farms in the past. In contrast, persistent S. Senftenberg strains induced an intestinal asymptomatic carrier state in chicks similar to S. Enteritidis, but a weaker systemic infection than S. Enteritidis in chicks and mice. An in vitro analysis showed that the low infectivity of S. Senftenberg is in part related to its low capacity to invade enterocytes and thus to translocate the intestinal barrier. The higher capacity of persistent than non-persistent strains to colonize and persist in the ceca of chickens could explain the increased persistence of S. Senftenberg in poultry flocks. This trait might thus present a human health risk as these bacteria could be present in animals before slaughter and during food processing.

The ability of genetically lean or fat slow-growing chickens to synthesize and store lipids is not altered by the dietary energy source

The increasing use of unconventional feedstuffs in chickens diets results in the substitution of starch by lipids as the main dietary energy source. To evaluate the responses of genetically fat or lean chickens to these diets, males of two experimental lines divergently selected for abdominal fat content were fed isocaloric, isonitrogenous diets with either high lipid (80 g/kg), high fiber (64 g/kg) contents (HL), or low lipid (20 g/kg), low fiber (21 g/kg) contents (LL) from 22 to 63 days of age. The diet had no effect on growth performance and did not affect body composition evaluated at 63 days of age. Glycolytic and oxidative energy metabolisms in the liver and glycogen storage in liver and Sartorius muscle at 63 days of age were greater in chicken fed LL diet compared with chicken fed HL diet. In Pectoralis major (PM) muscle, energy metabolisms and glycogen content were not different between diets. There were no dietary-associated differences in lipid contents of the liver, muscles and abdominal fat. However, the percentages of saturated (SFA) and monounsaturated fatty acids (MUFA) in tissue lipids were generally higher, whereas percentages of polyunsaturated fatty acids (PUFA) were lower for diet LL than for diet HL. The fat line had a greater feed intake and average daily gain, but gain to feed ratio was lower in that line compared with the lean line. Fat chickens were heavier than lean chickens at 63 days of age. Their carcass fatness was higher and their muscle yield was lower than those of lean chickens. The oxidative enzyme activities in the liver were lower in the fat line than in the lean line, but line did not affect energy metabolism in muscles. The hepatic glycogen content was not different between lines, whereas glycogen content and glycolytic potential were higher in the PM muscle of fat chickens compared with lean chickens. Lipid contents in the liver, muscles and abdominal fat did not differ between lines, but fat chickens stored less MUFA and more PUFA in abdominal fat and muscles than lean chickens. Except for the fatty acid composition of liver and abdominal fat, no interaction between line and diet was observed. In conclusion, the amount of lipids stored in muscles and fatty tissues by lean or fat chickens did not depend on the dietary energy source.

Evaluation of PCR and DNA Sequencing for Direct Detection of Clostridium perfringens in the Intestinal Tract of Broilers

Abstract The aim of this investigation was to determine the presence of the opportunistic pathogen Clostridium perfringens by PCR and DNA sequencing, without previous cultivation. This methodology was then used to investigate how C. perfringens was affected by different preventive measures, such as ionophores and feed additives, for necrotic enteritis in broilers chickens. DNA was extracted from the intestinal content or intestinal tissue by DNA extraction kits. Detection limits for 16S rRNA, alpha-toxin, and cpb2 PCR gene targets were approximately 1 × 103, 5 × 104, and 1 × 106 cells per g of intestinal content or tissue, respectively, as determined with samples spiked with C. perfringens. The method was evaluated with samples from single conventional broilers or from pools of six birds of experimentally reared broilers. Conventional chickens, raised with salinomycin in their feed, showed reduced numbers of C. perfringens-positive samples (P < 0.05) for all three PCR tests. With respect to cpb2, a tendency to detect more samples as positive for C. perfringens was observed with increasing age. The addition of sodium butyrate and lactic acid in the feed for experimental birds had a minor effect (P < 0.10) on positive samples, as detected with the 16S rRNA PCR. For experimental birds fed whole wheat, only three out of six pools of six birds allowed detection of C. perfringens by the 16S rRNA PCR, compared to five for the untreated controls or the Avilamycin- or prebiotic-treated birds. All 16S rRNA partial gene sequences obtained were identical and were 99.5% similar to the rrnB gene of the type strain of C. perfringens. Two types of the partial cpb2 gene sequence were detected with a similarity of 93%. One type was translated into protein, whereas a stop codon was found in the other type. Both types were located in the “atypical” phylogenetic group of the cpb2 gene sequences. The PCR test, based on extraction of DNA from intestinal content, provided rapid screening of poultry for C. perfringens without the need to have access to facilities in order to immediately cultivate and identify bacteria at the location of sampling. Further work is suggested to determine the relationship between the degree of necrotic enteritis, the actual level of C. perfringens in the animal, and the detection achieved by PCR.

The influence of a probiotic supplementation on memory in quail suggests a role of gut microbiota on cognitive abilities in birds

HighlightsQuail supplemented with Pediococcus acidilactici had a better memory.Pediococcus acidilactici had no consistent effect on the fear of quail.Traits of emotional reactivity did not explain the improvement of memory. Abstract The gut microbiota is involved in host behaviour and memory in mammals. Consequently, it may also influence emotional behaviour and memory in birds. Quail from two genetic lines with different fearfulness (LTI: long tonic immobility, n = 37; STI: short tonic immobility, n = 32) were either or not supplemented with a probiotic (Pediococcus acidilactici) from hatching. Emotional reactivity was measured in a tonic immobility test (d6 and 7 of age) and two open‐field tests (d13–15; d22–24). Memory was measured in a test rewarded with mealworms, where quail had to remember the cups previously visited (d34–36). Quail endured a 5‐days stress period from days 17 to 21 to help revealing the potentially beneficial effect of the probiotic. As expected, STI quail were less fearful compared to the LTI quail (p < 0.05). Probiotic supplementation had no effect on most measures of emotional reactivity (p > 0.05), except in the tonic immobility test where supplemented STI quail had lower immobility duration (p = 0.0001). Regarding the memory test, the two lines had similar performances. Quail fed with probiotics made fewer errors (p = 0.040). There was no significant correlation between traits of emotional reactivity and of memory. In conclusion, the supplementation with Pediococcus acidilactici as a probiotic, affected a specific trait of emotional reactivity in STI quail, and improved memory in both lines, whichstrengthens the idea that the influence of gut microbiota on the host behaviour and memory seen in mammals is shared by birds.

Role of systemic infection, cross contaminations and super-shedders in Salmonella carrier state in chicken: Salmonella carrier state mechanisms

Carriage of Salmonella is often associated with a high level of bacterial excretion and generally occurs after a short systemic infection. However, we do not know whether this systemic infection is required or whether the carrier-state corresponds to continuous reinfection or real persistence in caecal tissue. The use of a Salmonella Enteritidis bamB mutant demonstrated that a carrier-state could be obtained in chicken in the absence of systemic infection. The development of a new infection model in isolator showed that a marked decrease in animal reinfection and host-to-host transmission between chicks led to a heterogeneity of S. Enteritidis excretion and colonization contrary to what was observed in cages. This heterogeneity of infection was characterized by the presence of super-shedders, which constantly disseminated Salmonella to the low-shedder chicks, mainly through airborne movements of contaminated dust particles. The presence of super-shedders, in the absence of host-to-host transmission, demonstrated that constant reinfection was not required to induce a carrier-state. Finally, our results suggest that low-shedder chicks do not have a higher capability to destroy Salmonella but instead can block initial Salmonella colonization. This new paradigm opens new avenues to improve understanding of the carrier-state mechanisms and to define new strategies to control Salmonella infections.© 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.