Improving the efficiency of feed utilization in poultry by selection. 1. Genetic parameters of anatomy of the gastro-intestinal tract and digestive efficiency

<p>Abstract</p> <p>Background</p> <p>Feed costs represent about 70% of the costs of raising broilers. The main way to decrease these costs is to improve feed efficiency by modification of diet formulation, but one other possibility would be to use genetic selection. Understanding the genetic architecture of the gastro-intestinal tract (GIT) and the impact of the selection criterion on the GIT would be of particular interest. We therefore studied the genetic parameters of AMEn (Apparent metabolisable energy corrected for zero nitrogen balance), feed efficiency, and GIT traits in chickens.</p> <p>Genetic parameters were estimated for 630 broiler chickens of the eighth generation of a divergent selection experiment on AMEn. Birds were reared until 23 d of age and fed a wheat-based diet. The traits measured were body weight (BW), feed conversion ratio (FCR), AMEn, weights of crop, liver, gizzard and proventriculus, and weight, length and density of the duodenum, jejunum and ileum.</p> <p>Results</p> <p>The heritability estimates of BW, FCR and AMEn were moderate. The heritability estimates were higher for the GIT characteristics except for the weights of the proventriculus and liver. Gizzard weight was negatively correlated with density (weight to length ratio) of duodenum, jejunum and ileum. Proventriculus and gizzard weights were more strongly correlated with AMEn than with FCR, which was not the case for intestine weight and density.</p> <p>Conclusions</p> <p>GIT traits were largely dependent on genetics and that selecting on AMEn or FCR would modify them. Phenotypic observations carried out in the divergent lines selected on AMEn were consistent with estimated genetic correlations between AMEn and GIT traits.</p

Improving the efficiency of feed utilization in poultry by selection. 2. Genetic parameters of excretion traits and correlations with anatomy of the gastro-intestinal tract and digestive efficiency

<p>Abstract</p> <p>Background</p> <p>Poultry production has been widely criticized for its negative environmental impact related to the quantity of manure produced and to its nitrogen and phosphorus content. In this study, we investigated which traits related to excretion could be used to select chickens for lower environmental pollution.</p> <p>The genetic parameters of several excretion traits were estimated on 630 chickens originating from 2 chicken lines divergently selected on apparent metabolisable energy corrected for zero nitrogen (AMEn) at constant body weight. The quantity of excreta relative to feed consumption (CDUDM), the nitrogen and phosphorus excreted, the nitrogen to phosphorus ratio and the water content of excreta were measured, and the consequences of such selection on performance and gastro-intestinal tract (GIT) characteristics estimated. The genetic correlations between excretion, GIT and performance traits were established.</p> <p>Results</p> <p>Heritability estimates were high for CDUDM and the nitrogen excretion rate (0.30 and 0.29, respectively). The other excretion measurements showed low to moderate heritability estimates, ranging from 0.10 for excreta water content to 0.22 for the phosphorus excretion rate. Except for the excreta water content, the CDUDM was highly correlated with the excretion traits, ranging from -0.64 to -1.00. The genetic correlations between AMEn or CDUDM and the GIT characteristics were very similar and showed that a decrease in chicken excretion involves an increase in weight of the upper part of the GIT, and a decrease in the weight of the small intestine.</p> <p>Conclusion</p> <p>In order to limit the environmental impact of chicken production, AMEn and CDUDM seem to be more suitable criteria to include in selection schemes than feed efficiency traits.</p

Electrolyte balance in poultry feed formulation

International audienc

Dietary fiber and its interactions with minerals

International audienc

Intérêt nutritionnel de la pomme de terre pour exercer des effets alcalinisants

Les recherches des dernières décennies ont contribué à établir le rôle majeur joué par l'alimentation dans la prévention de nombreuses maladies. En particulier, l'évolution des régimes occidentaux a été marquée par une diminution de la consommation de produits végétaux, sources de glucides complexes et de micronutriments, et par l'utilisation croissante de produits transformés, ce qui favoriserait le développement de nombreuses pathologies dégénératives. Parmi les boulversements induits par cette "transition nutritionnelle", nous nous sommes intéressés aux conséquences de la diminution des apports de potassium et, en particulier, de sels organiques de potassium aux propriétés alcalinisantes dans un contexte où la charge acide de l'alimentation et les apports de sodium sont très élevés. Ces modifications du rapport Na/K pourraient participer au développement de pathologies chroniques telles que l'hypertension, l'ostéoporose et les lithiases rénales. La pomme de terre, longtemps considérée comme un simple féculent de faible intérêt nutritionnel, est en fait une source majeur de sels organiques de potassium présents principalement sous forme de citrate et de malate. L'intérêt des sels organiques de potassium provient de leur capacité à engendrer, après le métabolisme de leur partie organique, des équivalents bicarbonates de potassium, capables de neutraliser l'excès d'acidité résultant notamment du catabolisme des protéines ou de neutraliser les effets délétères du sel. Ainsi, les travaux menés au cours de cette thèse se sont attachés à mettre en évidence l'effet de la consommation de pomme de terre dans la régulation de l'équilibre acido-basique et minéral de l'organisme chez le rat et chez l'homme. Les résultats de ce travail de thèse ont confirmé que la pomme de terre était susceptible d'affecter favorablement l'équilibre acido-basique et l'homéostasie du calcium et du magnésium pouvant contribuer à limiter les altérations du tissu osseux. Par ailleurs, compte tenu de ses effets bénéfiques sur la citraturie, il est probable qu'elle puisse jouer un rôle dans la prévention des lithiases rénales. Des études à long terme chez l'homme sont toutefois nécessaire pour décrire les conditions dans lesquelles la consommation de pomme de terre peut être pleinement bénéfique via ses effets alcalinisants et sa contribution à la fourniture de glucides.Last decades studies established that the diet plays a major role in the prevention of several diseases. Particularly, Western diets presented a decrease in the consumption of plant foods, which represent a major source of complex carbohydrates and micronutrients, and an increase in processed foods, that may contribute to the development of various degenerative pathologies. Among every changes induced by this "nutritional transition", we studied the impacts of a decrease in potassium consumption, particularly potassium organic salts that present alkalinizing properties, in acid ash and high sodium diet conditions. The change in Na/K ratio may participate to the development of chronic pathologies such as hypertension, osteoporosis and renal lithiasis. Potato, considered for a long time as a starchy food with a poor nutritional interest, is in fact a major source of potassium organic salts present mainly in the form of citrate and malate. Potassium salts have the particularity to yield potassium bicarbonate, through their metabolism, that may neutralise the excess of acidity resulting from protein catabolism or deleterious effects of salt. We decided, thus, to focus in this thesis on the effect of potato consumption in the regulation of acid-base and mineral homeostasis in rats and humans. The results of the present thesis have confirmed that potato may positively affect acid-base and calcium and magnesium homeostasis contributing to limit bone alterations. Furthermore, taking into account the beneficial impact of potato on citraturia, it may play a major role in the prevention of renal lithiasis. Long term studies in humans remain essential in order to describe the conditions in which potato consumption may be effective through its alkalinizing impact and its contribution in carbohydrates supply.CLERMONT FD-BCIU-Santé (631132104) / SudocSudocFranceF

Pourquoi et comment intégrer la balance électrolytique dans les critères de formulation des aliments pour monogastriques ?

National audienc

Méta-analyse de l'utilisation digestive et métabolique du P chez le porc en croissance : effet de l'apport alimentaire de phosphore, de calcium et de phytase

National audienc

From Quantitative Trait Loci (QTL) discovery to nutrigenetics

The study of the interactions between genetics and nutrition has gained new impetus with the development of high-throughput genomic approaches allowing for a comprehensive approach of the variability of gene sequences or activity. The object of nutrigenetics is to identify the genetic determinants (sequence polymorphisms) of the variability of individual responses to nutrition. A quantitative trait locus (QTL) is a chromosomal region involved in the control of quantitative phenotypic traits. Based on the knowledge of the chicken genome sequence, numerous positional candidate genes can be proposed within a QTL region, and further evaluation is needed to test the link between polymorphism of those genes, their activity and the expression of the phenotype. As a proof of principle that such an approach is relevant to nutrigenetics, we identified a polymorphism in the gene encoding the enzyme -carotene 15,15'-monooxygenase 1 (BCMO1), which affected the response to dietary intake of -carotene in term of plasma, liver and duodenal concentrations of lutein. Another project aims to identify the genetic determinants of digestive ability through the development and characterization of two experimental lines of chickens divergently selected for this trait. Recently, chromosomal regions controlling this trait have been identified, and further studies of sequence polymorphisms and gene expression (functional genomics) data in extreme animals issued from a cross population are underway. Eventually, the tools of nutrigenetics will predict the potential for adaptation of genotypes to various feeds. Nutrigenomics, allowing a better understanding of the mechanisms by which nutrition affects gene activity, is expected to propose new nutritional strategies to guide phenotypes and new selection strategies to improve birds’ ability to adapt to different diets. The combination of both approaches should permit to identify genes controlling those phenotypes

Vitamine D and métabolisme phosphocalcique chez la poule pondeuse

National audienc