Michel Lessire

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.

Plasma lipoprotein distribution in the turkey (Meleagris gallopavo)

The plasma lipoprotein profile has been determined in fasted 7-week-old male turkeys. Lipoprotein classes were subfractionated by density gradient ultracentrifugation. According to phospholipid concentration over the density gradient, an initial peak was visible in the usual LDL density range, whereas two peaks were detected in that of HDL. As density increased, the lipid composition of particles showed an increase in cholesteryl esters and decrease in triglycerides. VLDL were recovered in the first fraction (d<1.013) on the top of the gradient and IDL in fractions 2-5 (d=1.013-1.028 g/ml). The LDL and HDL populations in the density range 1.028-1.090 (fractions 6-12) differ from that found in the other bird species analyzed under the same experimental conditions. LDL predominated in fractions 6-8 with mostly beta-motility and apoB100 as the major protein component. HDL predominated in fractions 10-12 (d=1.055-1.090 g/ml) and corresponded to the first HDL peak (HDL-(A)), with mostly alpha-mobility and apoA-I as the major protein component. Both LDL- and HDL-like particle populations were present in fractions 6-12, making the separation between the two classes of lipoproteins difficult. The second peak in the HDL density range (HDL-(B), d=1.076-1.146 g/ml) contained only HDL-type particles above d=1.090 g/ml. This points out the specificity of the lipoprotein distribution in the turkey that is unique among animals. The density limit at d=1.048 g/ml is a good compromise for the separation of LDL from HDL; however, the presence of HDL-like particles in the LDL density range, and the existence of two, and even three HDL subclasses should be taken into account in the design of further metabolic studies.

Metabolisable energy value of fats in chicks and adult cockerels

Abstract The metabolisable energy (ME) values of beef tallow, animal fat and poultry fat were determined by various methods using two- or six-week-old chicks and adult cockerels. The ME value of tallow increased with the age of the bird, but no parallel changes in either digestibility or ME of unsaturated fats were observed. The difference between ME values obtained by digestibility studies and those obtained directly showed that added fat may increase the absorbability of other constituents of the diet, hence the ME obtained by difference may exceed gross energy in some cases.

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.

Energy value of wheat dried distillers grains with solubles in roosters, broilers, layers, and turkeys

Four experiments were conducted to measure total tract metabolizability of gross energy (GE), the AME, and AMEn or AME content corrected for a standardized N retention (AMEs) of 10 European wheat dried distillers grains with solubles (DDGS) in roosters, broilers (3 wk old), layers (25 wk old), and growing turkeys (10 wk old). The wheat DDGS were obtained from 7 European ethanol plants and selected to get a large variability in chemical composition. The AME, AMEn, or AMEs of wheat DDGS was obtained according to the difference method. The highest AMEn:GE was obtained for roosters with an average (minimum-maximum) value of 49% (43-55), the lowest in turkeys (43%; 34-50), and intermediate values (47%; 41-57 and 46%; 36-50) in broilers and layers, respectively. Corresponding AMEn values were 10.3 (9.0-11.3), 9.9 (8.5-11.7), 9.6 (7.8-10.5), and 9.6 (7.8-10.5) MJ/kg of DM for roosters, broilers, layers, and turkeys, respectively. The AMEs for N retention equal to 50% of N intake was about 0.6 MJ higher than the corresponding AMEn value. Our data indicate that the AMEn content of wheat DDGS can be predicted from either their acid detergent fiber content (R2=0.79) or the lightness score (L*; R2=0.77) with a common slope but different intercepts for the 4 poultry categories. If dark and overheated samples (L*<50; n=3) with the lowest AMEn:GE ratio and AMEn values are excluded, the average AMEn:GE ratio becomes 51, 49, 48, and 45% in roosters, broilers, layers, and turkeys, respectively, with corresponding AMEn values of 10.7, 10.2, 10.0, and 9.5 MJ/kg of DM that are more representative of a well-controlled process for DDGS preparation. The negative effect of L* on energy value and energy metabolizability indicates that overheating while drying should be minimized to maximize the energy value of wheat DDGS for poultry. Finally, equations for predicting AME values in layers, broilers, or turkeys from the AME values in roosters are proposed.

Effect of dietary fats on hepatic lipid metabolism in the growing turkey

The influence of dietary fatty acids on hepatic capacity of lipid synthesis and secretion was investigated in 7-week-old male turkeys. They were fed 10% of either lard (rich in saturated and monounsaturated fatty acids) or linseed oil (rich in polyunsaturated fatty acids, especially 18:3n-3). Fattening was identical with both diets (0.15-0.20% of abdominal adipose tissue), but the proportion of muscle Pectoralis major was lower with linseed oil (6.6 vs. 7.4%). Specific activities of lipogenic enzymes (ME, G6PDH, ACX, and Delta9-desaturase) were not influenced by the diet, however, FAS activity was lower with linseed oil (14.3 vs. 25.4 nM NADPH fixed/min). Fasting concentrations of lipoproteins synthesized and secreted by the liver, VLDL and HDL, were also lower with linseed oil, as well as plasma concentrations of phospholipids and cholesteryl esters. However, when VLDL catabolism was inhibited by injection of an antiserum against LPL, VLDL concentration was identical in both groups (100-120 mg/l), whereas that of phospholipids and cholesteryl esters, that are transported by HDL mainly, remained lower with linseed oil. Thus, in the growing turkeys, and contrary to mammals and the chicken, feeding n-3 polyunsaturated fatty acids did not decrease hepatic triglyceride synthesis and secretion, nor fattening. By contrast, in this species, n-3 polyunsaturated fatty acids appear to influence mostly HDL metabolism, with a negative impact on muscular growth.

Changes in body composition in broilers by a sulfur amino acid deficiency during growth

In the factorial approach, amino acid (AA) requirements are determined using the AA composition of retained protein, which is assumed to be constant. However, this hypothesis may not be valid because the AA composition of body protein can be affected by the diet. The objective of this study was to quantify the changes in chemical body composition of broilers receiving diets either deficient (TSAA-) or sufficient (TSAA+) in TSAA. Diet TSAA+ was formulated according to the Ross recommendation. Diet TSAA- provided 36% true digestible Met:Lys and 64% true digestible TSAA:Lys, which were, respectively, 34 and 22% lower compared with diet TSAA+. Performance and tissue weight gain between 7 and 42 d of age were not affected by the TSAA supply. In TSAA- chickens, protein gain was lower in the carcass (P < 0.01) and tended to be lower in the empty body (P = 0.06) and pectoralis major muscle (P = 0.10). Compared with TSAA+ chickens, lipid gain in TSAA- chickens was 78% greater in the pectoralis muscle (P < 0.001), 28% greater in abdominal fat (P < 0.05), and 10% greater in the carcass (P = 0.10). In the pectoralis muscle, there was a tendency for an increase in the redness value (a*; P = 0.10). The TSAA supply affected the AA composition of tissues and tissue gain, but the Met and Cys concentrations were changed only in the offal (P = 0.08). The deficient TSAA supply resulted in an increase in the Ser concentration in the empty body, carcass, and pectoralis muscle (P < 0.05). In contrast, it resulted in a decrease in the concentrations of Lys and Glu in the empty body, of Phe, Tyr, Gly, and Glu in the pectoralis muscle, and of Ala in the offal (P < 0.05). This indicates that although chickens cope with a TSAA deficiency predominantly by changing the protein and lipid concentration in the body, the AA composition is also affected. This calls into question the use of a constant ideal AA profile in poultry nutrition.

Effect of sex and genotype on carcase composition and nutritional characteristics of chicken meat

1. The aim of this study was to examine the effect of sex and genotype on carcase composition and nutritional and sensory characteristics of chicken meat. The “Géline de Touraine” (GT) characterised by high carcase fatness was compared with an experimental crossbreed (EC) and “Label rouge” (LR) genotype. 2. Females compared with males, and GT chickens compared with LR and EC chickens were characterised by increased carcase fatness and an increased lipid level in thigh meat. 3. In both breast and thigh meat, the percentage of monounsaturated fatty acids was increased and the percentage of polyunsaturated fatty acids was decreased. However, these effects did not affect sensory characteristics of meat particularly those of roasted breast fillets containing very low lipid level by comparison with thigh meat. 4. Finally, in our study, high carcase fatness was related to high intermuscular fatness affecting the nutritional characteristics of meat but not its sensory attributes.

Influence of grand-mother diet on offspring performances through the male line in Muscovy duck

BackgroundIn mammals, multigenerational environmental effects have been documented by either epidemiological studies in human or animal experiments in rodents. Whether such phenomena also occur in birds for more than one generation is still an open question. The objective of this study was to investigate if a methionine deficiency experienced by a mother (G0) could affect her grand-offspring phenotypes (G2 hybrid mule ducks and G2 purebred Muscovy ducks), through their Muscovy sons (G1). Muscovy drakes are used for the production of mule ducks, which are sterile offspring of female common duck (Anas platyrhynchos) and Muscovy drakes (Cairina moschata). In France, mule ducks are bred mainly for the production of “foie gras”, which stems from hepatic steatosis under two weeks of force-feeding (FF). Two groups of female Muscovy ducks received either a methionine deficient diet or a control diet. Their sons were mated to Muscovy or to common duck females to produce Muscovy or Mule ducks, respectively. Several traits were measured in the G2 progenies, concerning growth, feed efficiency during FF, body composition after FF, and quality of foie gras and magret.ResultsIn the G2 mule duck progeny, grand-maternal methionine deficiency (GMMD) decreased 4, 8, and 12 week body weights but increased weight gain and feed efficiency during FF, and abdominal fat weight. The plasmatic glucose and triglyceride contents at the end of FF were higher in the methionine deficient group. In the G2 purebred Muscovy progeny, GMMD tended to decrease 4 week body weight in both sexes, and decreased weight gain between the ages of 4 and 12 weeks, 12 week body weight, and body weight at the end of FF in male offspring only. GMMD tended to increase liver weight and increased the carcass proportion of liver in both sexes.ConclusionAltogether, these results show that the mother’s diet is able to affect traits linked to growth and to lipid metabolism in the offspring of her sons, in Muscovy ducks. Whether this transmission through the father of information induced in the grand-mother by the environment is epigenetic remains to be demonstrated.

Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens.

Feeding broilers by alternating different diets for 1 or 2 days is known as sequential feeding, and it possibly reduces leg problems since it slows down early growth and may enhance general activity. The present study compared continuous feeding with a standard diet (C: metabolisable energy = 12.55 MJ/kg, crude protein = 190 g/kg) with alternations of a high-energy/low-protein diet (E+P-:+7% ME; -20% CP) and a low-energy/high-protein diet (E-P+: -7% ME,+20% CP) and investigated its effects on growth, behaviour and gait score in 352 male Ross broiler chickens. Sequential feeding was carried out during ten 48-h sequential-feeding cycles from 8 to 28 days of age. Three treatments were compared: complete diet (C) and two alternations of diets varying in protein and energy contents (S1: E+P- followed by E-P+; and S2: E-P+ followed by E+P-). Chickens received the same feed during the starter and finisher periods (0 to 7 and 29 to 38 days of age). Body weight (BW), feed intake, general activity and gait score, bone quality and carcass conformation were measured to evaluate leg condition and general performance. Sequential feeding significantly reduced BW at 28 days of age (S1: -9.1%; S2: -3.7%/C group; P < 0.05) and S1 were lighter than S2. In both sequential groups, time spent standing increased (C: 28%; S1:33%; S2: 35%; P < 0.05) and leg abnormalities decreased (mean gait score: C: 2.61; S1: 2.45; S2: 2.38; P < 0.02). This improvement was not related to changes in bone quality. BW at slaughter was impaired in Group S1 only, and the feed conversion ratio throughout the rearing period was not significantly impaired by sequential feeding. However, abdominal fat was higher in the S2 group. Sequential feeding using diets varying in energy and crude protein can be a useful method of reducing leg problems in broilers since it improves gait score without impairing growth performance when used as early as 8 days of age and up to not less than 8 days before slaughter in order to compensate for reduced growth. This improvement can be explained by reduced early growth and enhanced motor activity. However, it appears that the low-energy diet should be given first in order to avoid a reduction in BW at slaughter.