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Reports developments related to the nutrition of poultry in Algeria as of December 2001. Percentage of imported poultry feedstuffs; Use of extrude full fat soyabean in laying hens diets; Role of satiety hormone leptin secreted by adipocytes.

Abstract In hens, the ovarian follicles committed to ovulation are arranged in an ordered follicular hierarchy. In standard broiler breeders hens genetically selected for high growth rate the reproductive function is clearly dysfunctional. Feed restriction is needed during reproductive development to limit the formation of excessive numbers of ovarian yellow follicles arranged in multiple hierarchies. To determine whether leptin is involved in the nutritional and reproductive interactions controlling follicular hierarchy in hens, blood leptin levels and ovarian expression of the leptin receptor mRNA were determined during follicle maturation in three chicken lines; a slow growing broiler "Label" genotype without reproductive dysfunction, a fast growing "Standard" genotype fed ad libitum or restricted and a fast growing "Experimental" line with intermediate reproductive performance levels. Whereas expression of the leptin receptor mRNA did not change in the theca, it clearly decreased with follicular differentiation in the granulosa of slow growing hens. In fast growing standard hens fed ad libitum and presenting significant reproductive dysfunction, the decrease was disrupted and dramatic up-regulation of granulosa cell expression of the leptin receptor was observed. On the other hand, feed restriction decreased the overall level of expression of the leptin receptor mRNA and restored the decrease with follicular growth. The level of expression of the leptin receptor probably modulates the action of leptin on follicular differentiation. Since blood leptin and other metabolic factors were not affected by the genotype or by nutritional state, the factors involved in the regulation of leptin receptor gene expression remain to be determined. This study demonstrates the involvement of leptin in the nutritional control of reproduction in birds. Leptin action on the ovary probably controls follicular hierarchy through the regulation of steroidogenesis.

Gizzard motility was compared between chickens from D+ (high digestion efficiency) and D- (low digestion efficiency) genetic lines selected for divergent digestion efficiency, using strain gauge transducers. Motility was recorded continuously during 24 h in 6 birds per line. Two stimuli, a meal distribution after a feed-deprivation period and lighting after a dark period, were tested during the recording period. A functional test with intravenous injection of serotonin performed at the end of the recording day often resulted in a sharp reduction in gizzard motility, without a significant difference between lines. Compared with D+ birds, gizzard activity in D- birds remained high during fasting or dark periods (P < 0.0006), which reduced the effects of stimuli in D- birds. So, coordination between bird activity and gizzard motility tended to be reduced in D- compared with D+ birds (P = 0.0018). This coordination was observed to be positively correlated (P = 0.011) with the relative weight (g/kg of BW) of the stomach (gizzard + proventriculus). This experiment pointed out differences in gizzard motility between D+ and D- chicken lines in terms of response to environmental stimuli, characterized by a failure in the gizzard relaxation process in D- birds during rest periods. [ABSTRACT FROM AUTHOR]

The effect of feeding nutritionally different diets in sequential or loose-mix systems on the performance of laying hen was investigated from 16 to 46 wk of age. Equal proportions of whole wheat grain and protein-mineral concentrate (balancer diet) were fed either alternatively (sequential) or together (loose-mix) to ISA Brown hens. The control was fed a complete layer diet conventionally. Each treatment was allocated 16 cages and each cage contained 5 birds. Light was provided 16 h daily (0400 to 2000 h). Feed offered was controlled (121 g/bird per d) and distributed twice (4 and 11 h after lights-on). In the sequential treatment, only wheat was fed at first distribution, followed by balancer diet at the second distribution. In loose-mix, the 2 rations were mixed and fed together during the 2 distributions. Leftover feed was always removed before the next distribution. Sequential feeding reduced total feed intake when compared with loose-mix and control. It had lower wheat (-9 g/bird per d) but higher balancer (+ 1.7 g/bird per d) intakes than loose-mix. Egg production, egg mass, and egg weight were similar among treatments. This led to an improvement in efficiency of feed utilization in sequential compared with loose-mix and control (10 and 5%, respectively). Birds fed sequentially had lower calculated ME (kcal/bird per d) intake than those fed in loose-mix and control. Calculated CP (g/bird per d) intake was reduced in sequential compared with loose-mix and control. Sequentially fed hens were lighter in BW. However, they had heavier gizzard, pancreas, and liver. Similar liver lipid was observed among treatments. Liver glycogen was higher in loose-mix than the 2 other treatments. It was concluded that feeding whole wheat and balancer diet, sequentially or loosely mixed, had no negative effect on performance in laying hens. Thus, the 2 systems are alternative to conventional feeding. The increased efficiency of feed utilization in sequential feeding is an added advantage compared with loose-mix and thus could be employed in situations where it is practicable. [ABSTRACT FROM AUTHOR]

Background: Improving feed efficiency is a major goal in poultry production in order to reduce production costs, increase the possibility of using alternative feedstuffs and decrease the volume of manure. However, in spite of their economic and environmental impact, very few quantitative trait loci (QTL) have been reported on these traits. Thus, we undertook the detection of QTL on 820 meat-type chickens from a F2 cross between D- and D+ lines that were divergently selected on low or high digestive efficiency at 3 weeks of age. Birds were measured for growth between 0 and 23 days, feed intake and feed conversion ratio between 9 and 23 days, breast and abdominal fat yields at 23 days, and the anatomy of their digestive tract (density, relative weight and length of the duodenum, jejunum, ileum, and ratio of proventriculus to gizzard weight) was examined. To evaluate excretion traits, fresh and dry weight, water content, pH, nitrogen to phosphorus ratio from 0 to 23 days, and pH of gizzard and jejunum contents at 23 days were measured. A set of 3379 single nucleotide polymorphisms distributed on 28 Gallus gallus (GGA) autosomes, the Z chromosome and one unassigned linkage group was used for QTL detection., Results: Using the QTLMap software developed for linkage analyses by interval mapping, we detected 16 QTL for feed intake, 13 for feed efficiency, 49 for anatomy-related traits, seven for growth, six for body composition and ten for excretion. Nine of these QTL were genome-wide significant (four for feed intake on GGA1, one for feed efficiency on GGA2, and four for anatomy on GGA1, 2, 3 and 4). GGA16, 19, and 26 carried many QTL for different types of traits that co-localize at the same position., Conclusions: This study identified several QTL regions that are involved in the control of digestive efficiency in chicken. Further studies are needed to identify the genes that underlie these effects, and to validate these in other commercial populations and for different breeding environments.

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.

Fast-growing chickens have a limited ability to tolerate high temperatures. Thermal manipulation during embryogenesis (TM) has previously been shown to lower chicken body temperature (Tb) at hatching and to improve thermotolerance until market age, possibly resulting from changes in metabolic regulation. The aim of this study was to evaluate the long-term effects of TM (12 h/d, 39.5°C, 65% RH from d 7 to 16 of embryogenesis vs. 37.8°C, 56% RH continuously) and of a subsequent heat challenge (32°C for 5 h at 34 d) on the mRNA expression of metabolic genes and cell signaling in the Pectoralis major muscle and the liver. Gene expression was analyzed by RT-qPCR in 8 chickens per treatment, characterized by low Tb in the TM groups and high Tb in the control groups. Data were analyzed using the general linear model of SAS considering TM and heat challenge within TM as main effects. TM had significant long-term effects on thyroid hormone metabolism by decreasing the muscle mRNA expression of deiodinase DIO3. Under standard rearing conditions, the expression of several genes involved in the regulation of energy metabolism, such as transcription factor PGC-1α, was affected by TM in the muscle, whereas for other genes regulating mitochondrial function and muscle growth, TM seemed to mitigate the decrease induced by the heat challenge. TM increased DIO2 mRNA expression in the liver (only at 21°C) and reduced the citrate synthase activity involved in the Krebs cycle. The phosphorylation level of p38 Mitogen-activated-protein kinase regulating the cell stress response was higher in the muscle of TM groups compared to controls. In conclusion, markers of energy utilization and growth were either changed by TM in the Pectoralis major muscle and the liver by thermal manipulation during incubation as a possible long-term adaptation limiting energy metabolism, or mitigated during heat challenge.

The glucokinase (GK) enzyme (EC 2.7.1.1.) is essential for the use of dietary glucose because it is the first enzyme to phosphorylate glucose in excess in different key tissues such as the pancreas and liver. The objective of the present review is not to fully describe the biochemical characteristics and the genetics of this enzyme but to detail its nutritional regulation in different vertebrates from fish to human. Indeed, the present review will describe the existence of the GK enzyme in different animal species that have naturally different levels of carbohydrate in their diets. Thus, some studies have been performed to analyse the nutritional regulation of the GK enzyme in humans and rodents (having high levels of dietary carbohydrates in their diets), in the chicken (moderate level of carbohydrates in its diet) and rainbow trout (no carbohydrate intake in its diet). All these data illustrate the nutritional importance of the GK enzyme irrespective of feeding habits, even in animals known to poorly use dietary carbohydrates (carnivorous species).

Background: Improving digestive efficiency is a major goal in poultry production, to reduce production costs, make possible the use of alternative feedstuffs and decrease the volume of manure produced. Since measuring digestive efficiency is difficult, identifying molecular markers associated with genes controlling this trait would be a valuable tool for selection. Detection of QTL (quantitative trait loci) was undertaken on 820 meat-type chickens in a F2 cross between D- and D+ lines divergently selected on low or high AMEn (apparent metabolizable energy value of diet corrected to 0 nitrogen balance) measured at three weeks in animals fed a low-quality diet. Birds were measured for 13 traits characterizing digestive efficiency (AMEn, coefficients of digestive utilization of starch, lipids, proteins and dry matter (CDUS, CDUL, CDUP, CDUDM)), anatomy of the digestive tract (relative weights of the proventriculus, gizzard and intestine and proventriculus plus gizzard (RPW, RGW, RIW, RPGW), relative length and density of the intestine (RIL, ID), ratio of proventriculus and gizzard to intestine weight (PG/I); and body weight at 23 days of age. Animals were genotyped for 6000 SNPs (single nucleotide polymorphisms) distributed on 28 autosomes, the Z chromosome and one unassigned linkage group., Results: Nine QTL for digestive efficiency traits, 11 QTL for anatomy-related traits and two QTL for body weight at 23 days of age were detected. On chromosome 20, two significant QTL at the genome level co-localized for CDUS and CDUDM, i.e. two traits that are highly correlated genetically. Moreover, on chromosome 16, chromosome-wide QTL for AMEn, CDUS, CDUDM and CDUP, on chromosomes 23 and 26, chromosome-wide QTL for CDUS, on chromosomes 16 and 26, co-localized QTL for digestive efficiency and the ratio of intestine length to body weight and on chromosome 27 a chromosome-wide QTL for CDUDM were identified., Conclusions: This study identified several regions of the chicken genome involved in the control of digestive efficiency. Further studies are necessary to identify the underlying genes and to validate these in commercial populations and breeding environments.

There is evidence that the E3 ubiquitin ligases muscle ring finger-1 (MuRF1) and atrogin-1, which mediate the ubiquitination of certain proteins and thereby their proteolysis, are regulated by cyclical nutritional treatments varying in lysine content. In order to explore further the regulatory mechanisms involved in metabolic adaptation to dietary changes, we investigated the effects of daily variations in energy [2800 (E-) followed by 3200 kcal/kg (E+)], protein [230 (P+) followed by 150g/kg (P-)] or both [E-P+ followed by E+P-] on muscle protein metabolism in 2-week-old male broiler chickens. Growth performance was similar for all treatments. Expression of atrogin-1 and MuRF1 was changed by alternation of diets varying in protein (higher expression with P- vs. P+) and energy content (higher expression with E- vs. E+). The expression of atrogin-1 was regulated with mixed diets (increase in E+P- vs. E-P+) but not that of MuRF1. Such regulation may involve the mammalian target of rapamycin (mTOR), which was more phosphorylated with P+ than with P-. Eukaryotic initiation factor 4E binding protein, p70S6 kinase and ribosomal protein S6, which are mTOR targets known to control protein synthesis, were highly activated by increased protein content (P+ vs. P-). The mechanisms coordinating the protein synthesis/proteolysis balance remain to be characterized., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Chickens mimic an insulin-resistance state by exhibiting several peculiarities with regard to plasma glucose level and its control by insulin. To gain insight into the role of insulin in the control of chicken transcriptome, liver and leg muscle transcriptomes were compared in fed controls and "diabetic" chickens, at 5 h after insulin immuno-neutralization, using 20.7K-chicken oligo-microarrays. At a level of false discovery rate <0.01, 1,573 and 1,225 signals were significantly modified by insulin privation in liver and muscle, respectively. Microarray data agreed reasonably well with qRT-PCR and some protein level measurements. Differentially expressed mRNAs with human ID were classified using Biorag analysis and Ingenuity Pathway Analysis. Multiple metabolic pathways, structural proteins, transporters and proteins of intracellular trafficking, major signaling pathways, and elements of the transcriptional control machinery were largely represented in both tissues. At least 42 mRNAs have already been associated with diabetes, insulin resistance, obesity, energy expenditure, or identified as sensors of metabolism in mice or humans. The contribution of the pathways presently identified to chicken physiology (particularly those not yet related to insulin) needs to be evaluated in future studies. Other challenges include the characterization of "unknown" mRNAs and the identification of the steps or networks, which disturbed tissue transcriptome so extensively, quickly after the turning off of the insulin signal. In conclusion, pleiotropic effects of insulin in chickens are further evidenced; major pathways controlled by insulin in mammals have been conserved despite the presence of unique features of insulin signaling in chicken muscle.

Glucose homeostasis exhibits several peculiarities in chickens (in short, presence of high glycemia and resistance to high doses of exogenous insulin). Though the full chicken glucokinase gene sequence is still lacking, several results suggest its existence. The functionality of chicken glucokinase (GK) has been further investigated using an activator of mammalian GK (GKA). In vitro, GKA decreased GK's S0.5(a) in a glucose-dependent manner in liver homogenates from either fasted or fed chickens; it also increased GK Vmax(a) in homogenates from fed chickens. In vivo, acute oral GKA administration (10-100 mg/kg) induced a potent and dose dependent hypoglycemic effect in fed chickens (starting between 15 and 45 min with a maximum effect at 40 mg/kg, P<0.0001). At this dose, plasma insulin levels showed erratic and minor changes in the early times (an increase at 5 min and a decrease at 10 min, P<0.05). At 90 min, when hypoglycemia had developed plasma insulin levels decreased under controls and plasma pancreatic glucagon levels increased over controls. Also at 40 mg/kg, GKA transiently inhibited food intake at about 3h (P<0.0001). In conclusion, GKA is a potent activator of chicken GK evidencing that the structure and the activity of chicken GK are similar to those of mammalian GK. At variance with results obtained in mammals, the potent GKA hypoglycemic action appears to rely mostly on an effect on liver GK in chicken. This fits with previous results and further support the hypothesis of a "deficient coupling" between Β-cell metabolism and insulin release in this species., (Copyright © 2010 Elsevier Inc. All rights reserved.)

We recently provided evidence of the presence of glucokinase (GCK) in the chicken liver [Berradi, H., Taouis, M., Cassy, S., Rideau, N., 2005. Glucokinase in chicken (Gallus gallus). Partial cDNA cloning, immunodetection and activity determination. Comp. Biochem. Physiol. B Biochem. Mol. Biol. 141, 129-139]. In the present study we addressed the question of whether nutritional regulation of GCK occurs. Several nutritional conditions were compared in chickens (5 weeks old) previously trained to meal-feeding. One group was left in the fasted state (F: 24h) and one was tested at the end of the 2h meal (refed: RF). Two other 2h meal-refed groups received an acute oral saccharose load (6ml/kg BW) just before the 2h meal and were sacrificed either at the end of the meal (Saccharose refed, SRF) or 3h later (SRF+3). Liver GCK mRNA and protein levels did not differ between F, RF and SRF chickens but were significantly increased in SRF+3 chickens (2-fold, p<0.05). GCK activity did not differ between F and RF chickens but increased significantly in SRF and SRF+3 chickens (1.7-fold, p<0.05). Chicken liver GCK expression (mRNA and protein) and activity were therefore inducible in these chickens by feeding a meal with acute oral administration of carbohydrate. These and recent findings demonstrating insulin dependency of the liver GCK mRNA and protein strongly suggest that GCK may have an important role in carbohydrate metabolism, including that of the chicken. However, even in these highly stimulatory conditions, liver GCK activity remained relatively low in comparison with other species. The latter result may partly explain the high plasma glucose level in the chicken.

In order to evaluate the role of insulin in chicken, an insulin immuno-neutralization was performed. Fed chickens received 1 or 3 i.v. injections of anti-insulin serum (2-h intervals), while fed or fasted controls received normal serum. Measurements included insulin signaling cascade (at 1 h in liver and muscle), metabolic or endocrine plasma parameters (at 1 and 5 h), and qRT-PCR analysis (at 5 h) of 23 genes involved in endocrine regulation, metabolisms, and transcription. Most plasma parameters and food intake were altered by insulin privation as early as 1 h and largely at 5 h. The initial steps of insulin signaling pathways including insulin receptor (IR), IR substrate-1 (IRS-1), and Src homology collagen and downstream elements: phosphatidylinositol 3-kinase (PI3K), Akt, GSK3, ERK2, and S6 ribosomal protein) were accordingly turned off in the liver. In the muscle, IR, IRS-1 tyrosine phosphorylation, and PI3K activity remained unchanged, whereas several subsequent steps were altered by insulin privation. In both tissues, AMPK was not altered. In the liver, insulin privation decreased Egr1, PPAR gamma, SREBP1, THRSP alpha (spot 14), D2-deiodinase, glucokinase (GK), and fatty acid synthase (whereas D3-deiodinase and IGF-binding protein 1 transcripts were up-regulated. Liver SREBP1 and GK and plasma IGFBP1 proteins were accordingly down- and up-regulated. In the muscle, PPAR beta delta and atrogin-1 mRNA increased and Egr1 mRNA decreased. Changes in messengers were partly mimicked by fasting. Thus, insulin signaling in muscle is peculiar in chicken and is strictly dependent on insulin in fed status. The 'diabetic' status induced by insulin immuno-neutralization is accompanied by impairments of glucagon secretion, thyroid axis, and expression of several genes involved in regulatory pathways or metabolisms, evidencing pleiotropic effects of insulin in fed chicken.